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Controller confusion.
An air heater controller's function is to switch the heater on and set the required temperature.
A water heater controller's function is to switch the heater on. A separate thermostat may control optional fan matrix heating.
It is usually fairly easy to upgrade your controller but sometimes extra wiring to them may be required to implement the extra facilities.
Modern Eberspacher air heater controllers should control the temperature of Airtronic D2 D4 D5, D1LCC, D1LC and similar air heaters. They are not suitable for older models like D1L, D3L, D5L heaters. Most modern versions will work on both 12 and 24 volts.
Some controllers do not have a temperature set control, these are for water heaters.
Timers like the 701 and 7 day timer are suitable for both air and water heaters.
A few controllers have diagnostic facilities which can be extremely helpful for identifying the cause of problems.
Ventilation buttons on controllers will not work with some heaters. **See 801 section.
D1LC D3LC and D5LC diagnostics are compatible and have an additional light flashing facility.
This page may help you decide which controller is the best option for your particular use.
Eberspacher have a list of controllers on http://www.eberspacher.com/download-centre/technical-documents/controllers.html

Eberspacher controllers.
The Rheostat controller was often fitted to Eberspacher D1LC,  D1LCC , D3LC and D3LCC heaters.
It can also control Eberspacher Airtronic heaters D2, D4 and D5 but ventilation mode switching will not work.
Major disadvantage is temperature has to be set each time it is switched on.
Eberspacher Rheostat controller plugged into its connector. If the connector is not available connection to the rheostat can be made with spade terminals. The two connectors on the right are diagnostics and BT timer.
Some rheostats have an extra anticlockwise switch position, this is possibly for ventilation setting on D#LC heaters. It will not work with Airtronic or D#LCC heaters. The D#LCC heaters had no ventilation function and there are a few rheostats that have the anticlockwise switch mechanically but no electrical contact is made, very odd!



Circuit of the Eberspacher Rheostat.

Identifier    Rheostat connector pin   Wire colour
a8             Pin 1        Brown/white
a7             Pin 2        Grey/red
                Pin 3        Brown
a1             Pin 5        Red
a2             Pin 6        Yellow



Rheostat controller.
The circuit is very simple so is the easiest controller to understand how Eberspacher heating control works.
A switch connects red and yellow wires together which turns the heater on.
The 430 ohm potentiometer and resistor set the target temperature.
Eberspacher specification for the control is it should adjust from 1750 to 2180 ohms.
The dotted link between the switch and the control indicates that they are mechanically linked to the same knob.
The LED and 1000 ohm resistor just give the green light indication.

Its simple design means you can make a similar controller cheaply, useful for diagnosing faulty controllers.
This can replace a faulty or missing controller, or with an extra switch it can provide an additional controller.
My van has two controllers, one in the cab and a second mounted in the back so that I can switch on before getting out of bed when working on shows.
The circuit is simple, a switch between red and yellow wires turns the heater on and off, the LED and 1000 ohm resistor give the green light indication. The 430 ohm potentiometer and resistor set the target temperature. The dotted link between the switch and the control indicates that on the original rheostat they are mechanically linked to the same knob, not essential for the replacement.
Eberspacher specification for the control is it should adjust from 1750 to 2180 ohms which gives the values shown on the circuit.
To an electronics engineer these values are non standard but can be easily solved with two extra resistors.

DIY rheostat  components.
Parts are not critical, I have given some general suggestions together with prices as a rough guide, total cost without box under £10.
Almost any standard switch can be used for the on/off switch, current and voltage rating is low.
'Toggle switches' on Ebay are less than £1.50 including postage.
Single or double pole, single or double throw ( SPST, SPDT, DPST, DPDT), all are suitable.
The separate LED and resistor can be replaced by a 12v LED if preferred, cost from about £1.50 for posh one with a chrome bezel.
Potentiometer, also called variable resistor, 470 ohm. (Note that 430 ohm is not a standard value for potentiometers).
Do not choose a preset type as it does not have a shaft for the knob.
Ebay '16mm Potentiometer / Variable Resistor 470R Lin'     £1.20 plus £1.10 postage for a pack of two July 2011.
Knob - choice is very much a personal preference.
Ebay '37mm Aluminium Inlay Potentiometer Knob Numbers Legend'    £0.99 plus £1.10 postage July 2011.
Resistors  0.6w metal oxide, about 25p each in Maplin.    1/4w carbon would also be ok.
Two resistors, 1k8 and  62k ohm are connected in parallel give 1750 ohms.
A 4k7 ohms resistor connected across the 470 ohm potentiometer changes it to 430 ohms.
Box may not be required if mounting on a panel otherwise its a personal choice.
A search for 'Project box' on Ebay lists several at various prices from £3.
Depending upon how you connect to the wiring loom you may require wire, connector pins, crimp connectors or a terminal strip.
Early generation heaters like D1L D3L D4L D5L usually have a switch which selects Ventilation, Off, Full and Half power settings. Its physical appearance is fairly similar to the rheostat controller and the two can be confused. They are not interchangeable. Some of the older manuals are poor quality reproductions and circuit drawings of the switch are not clear.

I used a DPDT switch so had two unused terminals that I used to join wires to the led and target temperature resistors. I use coloured sleeving to identify wires if correct colour wire is not in my spares box.
One we use as part of our quick testing setup.
Not an elegant front panel but functional for testing purposes.
The only redeeming feature of this device is it can also read and reset fault codes.
The timer part is primitive, it only allows you to set a time and day of the week for starting the heater. By default the timer shuts off after 2 hours. That period can be reduced but cannot be increased beyond the 2 hours. There is no daily setting for the day of the week. Once you select one of the 3 memories the other 2 are ignored so you cannot switch on and off automatically more than once without selecting a memory after the first has completed. The center button gives manual control. The on time depends on the voltage on the ignition wire, with +12v present heating is continuous, without the voltage the maximum period is 2 hours. The ignition wire normally is connected to the ignition switch supply which powers accessories like the radio. Ours is connected to the 12v supply via a switch which we use during fault diagnostics. Illumination is equally primitive, it uses a bulb and that has to be changed to suit 12 or 24 volt operation. On the rear of the timer are 3 pins with 12 and 24v printed either side of them but no mention in the manual so whether they do change the voltage is not known. Days of the week are in German on the models we have seen.
It can often lock up when power is applied, it just displays a symbol on the lower left like a car, no clock, heater button light is off and nothing works.There is no reset switch, you have to leave it unpowered for up to 24 hours until the capacitors discharge.
The button sequence for resetting the codes is un-necessarily complicated and involves switching the ignition on and off. You really need the Instruction manual for this timer.
Update March 2014 - I found a copy at http://butlertechnik.com/download/55/Eberspacher_Multifunctional_7_Day_Timer_Manual.pdf
Some faults including codes 15, 17, 50 lock the heater both for your safety and to protect the ECU. Always identify and remove the fault cause before unlocking.


Ebay is listing some timers November 2012:   Eberspacher 7 day timer 24v, 8EU 007 628-13,22 1000,31 69 00, MAN 81.61990.0089  The front looks like the normal timer but the number reveals it is modified for a MAN truck which has a modified heater control system. No details are available of the modifications made to these non standard timer versions during manufacture. We cannot be sure but it is quite possible that they will not work with a normal Eberspacher heater, see main Buying advice page.

A user bought one with a VW/AUDI logo which worked ok,    numbers  8EU 007 628-08       22 1000       30 67 00         7D0 963 261
Eberspacher 7 day timer with diagnostics.
A standard numbering system and wire colours for controllers would have made upgrading far easier than the present arrangement.
For each controller I am in the process of adding the same identifier codes a1 to a8 that are listed in the heater looms on the wiring page to make it easier to interconnect heaters and controllers.
Each modern air heater (D#LC, D#LCC, Airtronic) generally uses 4 wires for the main controller functions.
Water heaters have a preset temperature setting so do not use the grey/red wire.
An indicator light should be visible to show when the heater is on. Some certification engineers may also require an indicator in the cab or cockpit. If needed connect a 12v or 24v LED to the yellow and brown wires. Yellow is the positive + connection.


Controllers and wiring connections.
Eberspacher Mini Controller.
Simple to use controller. Basic replacement for a rheostat. (Ok for Airtronics, D#LC, D#LCC). Does not have diagnostics.
For a pdf copy of the instructions http://www.eberspacher.com/download-centre/technical-documents/operating-instructions.html

Press Heat button to switch on. Red LED illuminated.
Adjust temperature with rotary knob.
Press Off button to turn off.
Press Fan button for ventilation mode. Blue LED illuminated. (This mode will not work on D#LC or D#LCC models. **See 801 section).
Press Off button to turn off.
There are five wires from the mini controller and five wires from the heater loom.
No one could possibly make joining them difficult could they?  Eberspacher have!



Identifier
code
Loom
wire colour
Join to
Controller
connector
Controller
wire colour
Purpose
a1
Thin Red
--------
1
Red
+12 volts power to controller
a2
Yellow
--------
2
Yellow
Switch on signal from controller,  (+12v = On)
a7
Grey/red
--------
4
Grey
Set target temperature from controller
a8
Brown/white
--------
    l---
3
5
Brown
Yellow / violet
Reference earth to controller (0 volts)
Reference earth to controller (0 volts)
a6
Blue/white
--------
n/c


Identifier
code
Loom Wire colour

a1
Thin Red
+12 volts power to controller
a2
Yellow
Heater on / off  from controller,  (+12v continuous = On)
a7
Grey/red
Set target temperature from controller
a8
Brown/white
Reference earth to controller (0 volts)
a6
Blue / white
Diagnostics signals, (serial data, bi-directional)
a3
Grey
External temperature sensor to ECU - optional

Thin Brown
0 volts power (aka  Earth or negative supply)
Usually only used as negative for indicator lights
Three additional wires may be used depending upon the controller model.

This colour arrangement is very counter intuitive so let me explain it differently.
Join the red controller wire to the thin red loom wire and join the yellow controller wire to the yellow loom wire.
Join the grey controller wire to the grey / red loom wire, not the obvious grey wire!
Join both the brown and the yellow / violet controller wires to the brown / white loom wire, not the obvious brown wire!
Eberspacher 701 timer controller.
There are 6 models of 701 controller.

Identifier
code
Loom
wire colour
Join to
Controller
wire colour
Purpose
a1
Thin Red

Red
+12 volts power to controller
a2
Yellow

Yellow
Switch on signal from controller,  (+12v = On)
a7
Grey/red

Grey/red*
Set target temperature from controller
a8
Brown/white

Brown/white*
Reference earth to controller (0 volts)
a6
Blue/white

Blue/white
Diagnostics
Model
Description
701 10 003
Airtronic heaters, small white connector.
701 10 103
Airtronic heaters, larger black Molex connector.
701 10 005
D1LCC, D3LCC, D5LC, D8LC connector. Ventilation mode only works with Airtronic heaters.
701 10 105
D1LCC, D3LCC, D5LC, D8LC different connector. Ventilation mode only works with Airtronic heaters.
701 10 006
Limited to 1 hour maximum operation, see below for continuous operation bypass.
This model with no diagnostics was fitted to BT vans and is quite often offered second hand on ebay.
701 10 007
Water heaters only, no temperature ramp.
Eberspacher 801 Controller.
Eberspacher' s complete lack of consistency in naming controllers causes much confusion.
What's the fundamental difference between a 'Rheostat', a 'Modulator' and a 'Controller'?, Eberspacher manuals offer no explanation. As far as I can see nothing. Eberspacher seem to use these terms to describe the same basic unit, ie a device with the on / off switch and a set desired temperature function. Probably due to them using German technical translators to translate into English.
There is also a separate type of controller inside or close to the heater that is the 'brains' of the unit, ECU Electronic Control Unit on early heaters, ICU Integrated Control Unit on later versions, we always refer to these as ECU on these webpages.

A major problem buying second hand is separating modern types from those with a thermostat which will only work with older models like the D1L etc. Eberspacher and Espar information on older controllers is not available so identifying those can be impossible.
Some controllers are made by vehicle manufacturers.
Most controllers not listed here will probably be thermostat types, not suited to D#LC, D#LCC, Airtronic
I do not get to examine these controllers so cannot give advice, if anyone donates controllers I can examine them and publish details.
We are starting to expand this page to cover controllers where we have only partial information in the hope users can help with by adding more details.

Further problems are caused by many users thinking modern controllers are like conventional central heating thermostats. Except for a few models Eberspacher air heater controllers do not measure the ambient temperature, they just send a signal to the Eberspacher basically saying 'The control is set on warm' or 'The control is set on hot'. The heater measures the actual air temperature at its air inlet and adjusts the heat output to match the required controller setting.
If the heater is close by this can work ok but if it is farther away or in a locker the temperature there can be greatly different. You probably do get some control as the locker temperature is influenced by the cabin temperature but it is not good. It fails completely when the heater circulates fresh air. The sensor then thinks that the temperature of the outside air is the ambient temperature and of course that does not change as the heated area warms up.
Even worse if the outside temperature drops below its lowest setting, usually between + 5 and + 10°C, the Eberspacher can automatically switch to maximum heat output, completely ignoring the temperature controller setting.
The solution to both of these is to fit a remote temperature sensor. Details and advice are on our sensor page.
701 Timer with no diagnostics
(white Eberspacher logo) 701 10 006.



701 Timer with diagnostics
(blue Eberspacher logo).
Typical Ebay price £120  April 2015.


Typical Ebay price £45 to £55  April 2015.


This controller would be my personal choice for a heater if we did not already have diagnostic facilities.
Manual says it is only suitable for Airtronic models but it will control other models.
2100.81.003 normal version,   2100.81.001 run time 1 hour maximum (current 801 version replaces this with an optional facility)
Switching, temperature control and diagnostic facilities will work ok with D#LC and D#LCC heaters but the ventilation button will not work because of technical differences from the Airtronic heaters. **See below.
This controller is described as water heater compatible and is 12 / 24v.
For a pdf copy of the instructions http://www.eberspacher.com/download-centre/technical-documents/operating-instructions.html
Identifier
code
Loom
wire colour
Join to
Controller
wire colour
Purpose
a1
Thin Red

Red
+12 volts power to controller
a2
Yellow

Yellow
Switch on signal from controller,  (+12v = On)
a7
Grey/red

Grey/red
Set target temperature from controller
a8
Brown/white

Brown/white*
Reference earth to controller (0 volts)
a3
Grey

Grey
External temperature sensor (connect if wanted)
a6
Blue/white

Blue/white
Diagnostics
The 801 has two built in temperature sensors (bottom left). One is used to display the ambient temperature.
The second sensor provides an optional remote temperature sensor which can be connected if required.
If the controller location is not ideal, like on a cold outside wall or in a draft, a separate optional remote sensor may still be needed.
See the Remote sensor page for more information on remote temperature sensors and the wiring details.
For full 801 details see the manual http://www.eberspacher.com/download-centre/technical-documents/operating-instructions.html
but this here is a brief summary of the facilities.
Switch on manually: Press the heater button. Green LED illuminated.
Display shows ambient temperature at the 801, it never displays the heater internal sensor temperature.
Use the ^ and v buttons to set the temperature, adjustment range 5 to 32 °C.
Display shows target temperature during adjustment, then reverts to ambient temperature.
Switch off manually: Press the heater button.
Ventilation mode: Press the fan button until blue LED illuminates. (Will not work on  D#LC or D#LCC  **See below).
Switch off manually: Press the fan button.
Diagnostics: Press and hold the heater button until "dA" displayed.
The blue LED will briefly illuminate and flicker as data is transferred. (Uses the blue/white wire so this must be wired in).
Display shows F0 followed by fault code then scrolls through previously stored fault codes up to a maximum of 5.
An updated / corrected list of fault codes is on our Fault codes page.
We recommend you make a permanent record of these codes before wiping them as the information can be valuable for diagnosis.
Some faults including codes 15, 17, 50 lock the heater both for your safety and to protect the ECU. Always identify and remove the fault cause before unlocking.
Clear stored faults / unlock by pressing ^ and v buttons together. If a fault persists the heater is still faulty.
Press Heater button to exit diagnostics.



**Using the 801 701 and Mini controller with D1LCC   D3LCC   D1LC  D3LC  D5LC.
D1LCC  D3LCC  D1LC D3LC D5LC ventilation modes are not compatible.
Jim Warne connected an 801 to his D1LCC and found that after pressing the ventilation button the fan started for about 3 minutes before it stopped and then the heater started again. This is a restart then cooling down cycle.
It probably occurs with the D#LC models. Users confirmation would be appreciated.
It also occurs with the 801,  701 and mini controllers.
He disabled the ventilation button. This method could be used with the other controllers. (Photos please)



WARNING The grey/red wire can be confused with the grey wire depending on the viewing angle.
Making this mistake can damage the ECU.
Also do not use the brown loom wire instead of the brown/white. See Faults page Weird faults section.


*Brown and grey before July 2013.
Wiring details are colour for colour on the later 701s.

My DIY Rheostat.
Old type thermostat controllers for D1L D3L D4L D5L D7L and Fan matrix.
BT type 701 timer, white logo - extending the 1 hour period.
The 701 10 006 model has a 1 hour maximum on time but it can be bypassed with a simple manual switch.
Thanks to Paul who was selling a 701 on ebay for telling me how in his listing, we do not have one to try.
"This timer is from a BT van,which means it has seven day program, heat adjustment, no diagnostics but has been set to run for one hour only before cutting out, the way I got round this is to add a switch between the red and yellow wires, so before the hour is up hit the switch and it runs on, light on thermostat goes out, but it still allows setting temperature in normal manner"
Further info in answer to my follow up query -
"When the device is installed in the normal way, you then add a 12v switch between the red and yellow wires, and even when control back light goes off, you can still control the heat setting and timer just the same, back light comes back on when you adjust setting briefly, got to the point when I only switched it on via the 12v switch, worked fine."
He also mentioned he got the light to work via a second switch but could not remember how, my guess is he changed the wiring to the light so it was connected via the second switch to the yellow wire.



Each model is produced with or without diagnostics, blue Eberspacher label with diagnostics, white without.
Except where stated below only difference between models is the connector.
For a pdf copy of the instructions http://www.eberspacher.com/download-centre/technical-documents/operating-instructions.html

Press the heater button to switch on manually, the duration defaults to 1 hour, press again to increase duration by 10 mins, 30 min, 60 mins, 90 mins, 2 hours up to 8 hours, then continuous operation.   The 701 10 006 model is limited to 1 hour maximum.
Use the ^ and v buttons to set the temperature, 20 steps on the ramp so roughly 1 °C change per step.
    The 701 10 007 model is specifically for water heaters, it has no temperature ramp.
    Any other model can also be used for water heaters, the temperature ramp will be ignored.
Switch off manually: Press the heater button.
Ventilation (fan only) setting 1 hour only: Works with Airtronics, not with D#LC or D#LCC heaters  **See 801 section for details.
    Press the v button repeatedly to get minimum setting then hold it pressed until fan displayed.
    Cancel by pressing the ^ button repeatedly to get back to normal temperature setting.

Timer operation:  Three memories store day of the week and time settings.
    Durations are the same as manual operation, no continuous setting. Times cannot be altered once timer has switched heater on.
Diagnostics: Not applicable for models with a white logo
    With the heater switched on press and hold the heater button until "dAtA" displayed.
    Release key to display AF-- alternating with the current fault code. Step through the last 5 fault codes by pressing ^ or v buttons.
    An updated list of fault codes is on the fault codes page.
    We recommend you make a permanent record of these codes before wiping them as the information can be valuable for diagnosis.
Some faults including codes 15, 17, 50 lock the heater both for your safety and to protect the ECU. Always identify and remove the fault cause before unlocking.
    Clear stored faults / unlock by pressing ^ and v buttons together. If a fault persists the heater is still faulty.
    Press Heater button to exit.

12 / 24v with battery backup. Non replaceable battery has 10 to 15 year life expectancy.

The water heater version does not have the temperature setting resistors and grey/red and brown/white wires are omitted.

Change time and day
   Press and hold Clock button, adjust time with < >.
   Then adjust day with < >.
Heater operation with vehicle ignition switch off (or with pin 10 not wired).
   Press heat button, heater will operate for 120 minutes, countdown displayed can be changed by < > buttons, max 120 minutes.
   Switch heater off by pressing Heat button.
Heater default time of 120 mins can be permanently reduced.
   Press and hold < button for about 3 seconds until it flashes, release button then adjust with < >.
Heater operation with vehicle ignition switch in on or accessory position (with pin 10 wired).
   Press heat button, heater will operate without time limit.
   If ignition turned off heater will continue for 15 minutes unless run time changed with < > buttons
   Switch heater off by pressing Heat button.
Set programmable preheat times
   Press P button until desired memory 1 2 or 3 is shown.
   Use < > to set time.   Use < > to set day of week.
Using programmable times
   Press P button until desired memory 1 2 or 3 is shown.
   The Heat button will flash red when a timed program is selected.
   Cancel by pressing Heat button.

Retrieving stored fault codes
  Turn on heater with Heat button.
  Press and hold the Heat button, press the P key within 2 seconds, current fault code is displayed ( AF:00 if no fault)
  Use < > to step through the stored fault codes ,maximum 5, F1: to F5:
  We recommend you make a permanent record of these codes before wiping them as the information can be valuable for diagnosis.

Clearing the fault codes and unlocking  a locked ECU.
  This is definitely NOT user friendly!
  Pin 10 must be wired to the ignition (or to +12v via a switch) for this to work.
  Codes 15, 17, 50 lock the heater for your safety and for the ECU.  Identify and remove cause before unlocking.
Turn on the ignition to activate the timer display.
  Press the Heat button, current fault is now displayed.
  Press and hold the Clock button, press the P button within 2 seconds, current fault code is displayed ( AF:00 if no fault)
  Turn off the ignition.
  Press and hold the Clock button, press and hold the P button within 2 seconds.
  While holding both buttons pressed turn on the ignition and wait till display shows --:--
  Turn the heater off and back on with the Heat key.
  Press and hold the Clock button, press the P button within 2 seconds, display should show AF:00
  The ECU lock is cancelled after 3 seconds, the heater starts if there is no fault.

*Brown before July 2013.

Universal switch.
Early generation heaters like D1L D3L D4L D5L used a completely different type of controller. These thermostat type controllers are not compatible with modern air heaters. Similarly these old heaters cannot use modern controllers. Most non current Eberspacher controllers not shown above will be of this type. There are several different controller versions around but no Eberspacher manuals are available. I have details of this particular one, others I cannot help with wiring connections or advice. Most of them may be suitable for switching on / off the fans in water heater fan matrixes.
Universal switch panel label.
Switch contains a 12 or 24v bulb.
Universal switch left, rheostat right.
Universal switch left, rheostat right looks similar.
Terminal view of Universal switch left, rheostat right.
D7L wiring with Thermostat switching from
Full to Half power.
D7L wiring with Thermostat switching
On and Off.
Eberspacher controllers for Modern heaters.
Complicated switch drawings can be difficult to interpret. This shows which Universal switch pins are joined together in the four switch positions.
Cheap versatile 12v 7 day timer.
If you have a little DIY electronics experience and just need a very versatile 12v or 24v timer I found an article on conversion to 12 volt operation of a cheap mains plug-in timer at http://www.reuk.co.uk/Convert-Digital-Mains-Timer-To-Low-Voltage.htm

These timers are also on ebay July 2011 and give 10 ON/OFF programs which can be set to 1 minute accuracy.
The user can select either MANUAL ON, AUTO, or MANUAL OFF mode for total control.
There are 16 pre-programmed combinations of day or blocks of days:
One day per week: MO or TU or WE or TH or FR or SA or SU
Every Day: MO TU WE TH FR SA SU
Weekdays Only: MO TU WE TH FR
Weekends Only: SA SU
Every Day bar Sunday: MO TU WE TH FR SA
Every Other Day: MO WE FR, or TU TH SA or MO WE FR SU
First Half of Week: MO TU WE
Second Half of Week: TH FR SA

Water heater model without temperature control.
Air heater model with temperature control.



The case has a retaining latch in the center of each side.



Plastic prevents key operating.


Front and rear views of the 801 circuit board.  Photos Jim Warne.



EasyStart Controllers  T,  R,  Call.
These controllers only work with some heaters, such as Airtonic heaters after Summer 2008 which have Hi-Kit on the label.
One major difference to the other controllers is they do not use the grey/red wire to set the temperature, they use the blue/white diagnostics wire.
Manuals https://www.eberspaecher.com/en/download-center/operating-instructions/current-models.html  (Category = English)
EasyStart controllers are not common, we know very little about them.
The manuals are definitely not user friendly and the more I learn the less I want to deal with them.
For more information or advice on problems with these EasyStarts contact a dealer.
EasyStart T has a timer, EasyStart R is for remote operation.
EasyStart Call is for controlling the Eberspacher from your smartphone.


Initial setup option for latest version.
The latest version of the 801 series Digiital Controller (serial numbered above 5000) can be pre-programmed with three (or four) modes of heating / ventilation duration with either °C or °F readout.  Default setting is °F display with 10 hour maximum run.
1) Continuous heater run until the heater is switched off manually.
2) 1 hour maximum run duration if heater is not switched off manually, after which time the heater switches off automatically.
3) 10 hour maximum run duration if heater is not switched off manually, after which time the heater switches off automatically.

To change the duration setting
Disconnect the Digi-controller from power. Press and hold down the "UP” and “DOWN” keys. Re-apply power to the unit.
The display will read n0, n1, n2, n3, n4 or n5, release both keys.
Repeatedly press the “UP” or “DOWN” button until the display reads the required setting as follows:
Modes for controller with 6 presets:
n0 deg C, continuous run,       n1 deg F, continuous run
n2 deg C, 1 hour duration,       n3 deg F, 1 hour duration
n4 deg C, 10 hour duration,     n5 deg F, 10 hour duration (Factory preset)

Modes for controller with 8 presets:
n0 degC, continuous run time,   n4 degF, continuous run time
n1 degC, 1 hour run time,          n5 degF, 1 hour run time
n2 degC, 4 hour run time,          n6 degF, 4 hour run time
n3 degC, 10 hour run time,         n7 degF, 10 hour run time (Factory preset)
To store the new setting press the “Heat” key and the display will return to ambient temperature.


301 Modulator.
Warning - The 301 numbering range is also used by versions with thermostats.
For details of both types see controllers list on http://www.eberspacher.com/download-centre/technical-documents/controllers.html
12 and 24 volt versions are listed with different part numbers.
We do not have our own information on this controller.
We would appreciate pictures and ones with the case removed.


I found  this circuit diagram by Bob Wilcox on the internet some time ago but cannot find it now.
He described it as a 301 type controller 1989 vintage. I have corrected a major drawing error and added wiring information.
See Air Models pages for the D#LC diagnostic details. Diagnostics are for D#LC models only as they can give a flashing light signal.
Butler Technik advert picture
D1L or D3L heater switched thermostat.
301 Thermostat.
Which controller is best?
There are a number of different Eberspacher controllers so which one would we personally choose for a modern air or water heater?.
801 - general controller with ambient temperature display and diagnostics for finding faults.
701 (blue logo version) - controller with timer and diagnostics for finding faults.
EasyStart Select - Controller with diagnostics but only works with latest versions of heaters, see below. It will not work with any of our heaters. Check before you buy!
Mini controller - simple but as it has no diagnostics it is a poor fourth choice.






Halls advert picture for 301 Modulator.
If you have a 301 please photograph outside and inside.




Warning - The 301 numbering range is also used for later non thermostat versions. For details of both types see controllers list on http://www.eberspacher.com/download-centre/technical-documents/controllers.html  12 and 24 volt versions are listed with different part numbers. We do not have our own information on this controller, We would appreciate pictures and ones with the case removed.
401 Timer Modulator.
401 00 191  12v,     401 00 190   24v .


Photos of this unit and wiring wanted please.

Wiring details not available but probably:
a1   Red   +12v
a2   Yellow switch on signal
a3   Grey/Red  Set temperature
a8   Brown or brown/white



For a pdf copy of the instructions:
http://www.eberspacher.com/download-centre/technical-documents/operating-instructions.html



Unfortunately nothing on older Eberspacher controllers is straightforward. There is a controller in the same case with a label Comfort which is not a thermostat.
It probably is an early version of the 301 produced for the D#LC models.
VW Westfalia Controller.
The controller has various front panel fixtures and is often in VW Westfalia T3 / T25 Camper vans with D2L heaters. The 3 position switch selects Heat / Off / Ventilation. Thanks to an ebay seller for these photos.
Page from Eberspacher D2L manual.
That is all the information I have on this controller.
Operating the EasyStart Select.
To switch on the heater push any button to exit from sleep mode (automatic after 10s) and select the desired mode (ventilation or heating) with < or > keys. The corresponding icons will then flicker.
Two possible modes are available: continuous (air heater only) or operating time (air and water heaters).
- If a time limit has been set:
1-Long press on the OK button (for more than 2 sec) and the heater will run in continuous mode until it is manually switched off.
During service the display alternates between the ambient temperature and the selected temperature for air heaters.
2-Short press on the OK button (less than 2 sec) will set the heater on time-limited and will switch off automatically at the end of this duration.
- If no time limit (off) has been set (only for air heater):
Just press the OK button and the heater will run in continuous mode until it is manually switched off.
In any case you can select the desired temperature by 1° increment during service using < or >.

The controller provides 2 fault stage indications: general errors are displayed on the main screen whereas specific fault codes can be accessed in the workshop menu (see below)
If Err is displayed then see the fault codes menu (long press OK to exit)
Eru indicates a low battery power (software threshold, see below)
N5i indicates no communication with the heater
- - - indicates a sensor interruption (bad wires connection or open circuit)

Workshop menu (short list of the most useful menu items)
To enter in the workshop menu press simultaneously the < and the > buttons for 5 seconds.
Then navigate in the menu where items are labeled from 1.1 to 6.4.

Fault codes (see Eberspacher Fault codes section for a detailed description)
The heater must be switched on.
1.1: displays the current fault code
1.2: displays the five last fault codes recorded (from F1 to F5 using < or >)

Set undervoltage limit
3.1: setting range: 8 - 28 volt in 0.1 volt increments (display, e.g. 108 for 10.8 volt).
      This is additional to the undervoltage limit of 10.5 volts built into the heater, both limits will stop the heater.
       'Undervoltage limit offset' or 'Debounce time' options must be completely meaningless to all but professional engineers.

Setting the operating time
4.1: before switching on the heater, select the value with < and > (Off or 10 to 720 min).


Wiring
One major difference to most other controllers is it does not use the grey/red wire to set the temperature, it uses the blue/white diagnostics wire.
The controller uses four wires and they are the same color code as Airtronic or Hydronic loom wires.
Additionally two loom wires, grey/red and brown/white must be joined together for air heaters, these can easily be overlooked.
Pin1. red (RD) is power +
Pin3. brown (BN) is power - (earth)
Pin4. blue/white (BUWH) is diagnostic
Pin2. grey/black (GYBK) is for displaying controller light in combination with the car/boat light.





Eberspacher EasyStart  Select Controller.
The display and timer circuitry on the programmable digital timer is not powered directly by mains electricity. Instead a small 1.2V NiMH rechargeable backup cell is kept charged, and the display and electronics are powered from that. It can easily be modified to charge from the 12v battery. On this unit the mains circuitry is on a separate board and is not used, no mains connection is needed. The timer output switches a relay for the 12v Eberspacher. If that make of timer is no longer available I have not investigated but I expect other digital mains timer types probably use broadly similar circuitry.
Tip: I use clip top boxes from Pound shop for some of my non mains projects, can look a bit amateurish but they are only £1. If the timer front is mounted on a panel the box will just contain a few low voltage electronics components for mechanical protection and can be hidden so who cares what it looks like.
Cost of timer and components should be well under £20.
For more details visit the original website, thanks to the author for permission to copy parts of this article.
Please send full details and good quality photographs of each stage if you modify a different timer and we will add it to the site.
The extra circuitry required for 12v operation.
This replaces all the mains circuitry.
Unmodified mains timer.
This controller will only work with later heaters, eg Airtonic heaters (2008 and later). Check before buying.
This lack of any backwards compatibility is extremely poor design and severely restricts its use among our readers who often have older heaters. Personally I would not buy one, it would limit substituting components for diagnosis and none of our own heaters will work with it.
Despite Espar describing it as the new 801 controller that view is not shared by Eberspacher UK or ourselves.
Although this is possibly a good controller it does have major design limitations so cannot replace the 801.
One major difference to the other controllers is it does not use the grey/red wire to set the temperature, it uses the blue/white diagnostics wire.


Thanks to Sebastien Scannella for providing most of this evaluation and description.
Unlike the 801, there is no built in temperature sensor meaning that you need to use the heater's one, which is ok for air recycling mode but not for fresh air mode. [There are two places to connect temperature sensors which do different things and the sensors are also different resistances, another poor design limitation. See Fit Remote Sensor section for more details and diagram].
It can be used with suitable Airtronic or Hydronic heaters either on 12 or 24V and has temperature control and ventilation mode capabilities (only for air heaters) as well as continuous (off duration selected) and time-limited modes (up to 720 min: by 1-min steps from 10 to 120 min and 5-min steps from 120 to 720 min).
For time modes configuration see workshop menu below.
Once connected to the heater and powered, the controller initiates and automatically detects the heater type and remote temp sensor if one is fitted. For an air heater like the D2 it will display the heater air inlet temp (or the remote temp sensor if one is fitted).
With a water heater it will only display ventilation and heating icons.
[Automatic selection may be a good idea but not at the expense of a manual mode for use with earlier models.]

EasyStart Select initial display for water heater (left) and air heater (right)
EasyStart Select air heater wiring.
Optional wiring is shown dotted.


EastStart Select manuals are on Espar site.
For full menu items see: http://www.esparparts.com/techsupport/pdfs/Control%20options%20and%20remote%20controls/Easy%20Start/Remote/Easy%20Start%20Plus%20schematics.pdf




EasyStart Select Hydronic heater wiring.



Mini controller



801 controller



The controller is the part you use to switch on / off, not the ECU inside the heater.
Typical Ebay price £48 to £55 April 2015.