Fix My Fridge

Specialists in the repair and service of 12v & 24v truck, campervan & boat fridges

wells vw california

KB id: 

I have a built in cool box using danfoss bd35f r134a 12v compressor and 101n0220 control box. the unit is factory installed by VW in a california camper. the compressor will not run when activated. I have read your diagnostic notes but there is no led display fitted. can you recommend/ supply a suitable one? i have tried using a meter to record the voltage sequence being put out on the D terminal but do not get consistent results so i want to try the led.should i disconnect the existing wire which i assume goes to the vw bulkhead display unit. this unit does not display the error code but knows there is a fault because it switches off the fridge. when this wire is connected and the bulkhead display is 'off' the D terminal outputs about 0.4v max if 'on ' it is nearer 5v. which is the right value for the led?
the vw dealer claims they cannot diagnose whether the fault is the control box or fridge and wish to replace each part speculatively at my expense. i cannot see any way to remove the fridge from the vehicle. are you familiar with the california application ? are you able to work on it in situ if i came with the vehicle? what would you expect a complete replacement to cost?
thank you in anticipation for your help


Your problem will be electrical.  I am not sure of the exact wiring of the dashboard panel of the California but the wiring to the fridge is something we can help on.  To run an LED test you need a standard 12V LED, we can supply one if it helps ( 

To test, locate the compressor and you will see an electrical box on the side where all the wiring is connected.  Plug the LED onto the small + and D terminals and then switch the power on to the fridge - if you need to remove any wiring to do this make sure you label so you can reassemble correctly.  You may also want to link out the thermostat (terminals C & T) to do this test so the compressor will definitely try and start if there is more than 11.5V

If there is power to the compressor but it does not start the LED will flash a number of times every 4 seconds.  Basic interpretation of the results is that if you get one flash, it is most likely to be the power supply on the vehicle, if you are getting 2,4 or 5 it is likely to be the controller.  three maybe power supply ofr the controller which is faulty. Download the manual Bd35/50 Fault Diagnostics which will run through this in more detail.

We are not really set up for working on vehicles here, but we can certainly give you help to test the system yourself or find a friendly electrical engineer who can do the tests for you.  You do not need a fridge engineer and much as I would like to sell you a new fridge - I very much doubt you need one.

Let us know how you get on with the LED test.

Kind regards


FmF technical help

thank you - i will obtain led and test as you describe. you seem to be saying that it is more likely to be the controller than the compressor that is faulty . if i were to return the controller to you would you be able to test it before i commit to ordering a new one from you?

No problem for us to test the controller here - if the unit is faulty and you buy a replacement there is no charge, otherwise we charge £15 to test plus return carriage (£2.95 ex VAT).  I recommend that you test it yourself if you can as the problem may be the electrics in the vehicle.  Our postal address is:

Penguin Refrigeration Ltd
Unit 2B Alexandria Park
Penner Rd
Havant  PO9 1QY

Tel 02392 453430

I have carried out led test and got code 3. i am therefore returning the controller to you for testing and if found to be faulty the supply of a suitable replacement. you will note i have had to make a modification to the connection between unit and compressor since the access to the unit in situ is very difficult. i hope this doesnt confuse the issue.

As long as the 3 pin plug is still attached to the controller we should be able to test OK.  If not already in the post, please mark for my attention (Zeb) and ensure you add your details to the package including contact telephone number and we can the contact you accordingly.


yes the plug is still on and i did test continuity between the plug and the unit! posted to you today first class but didnt see this before so it isnt marked specifically for you. there is a covering letter confirming my details and a copy of this support thread.

That's fine, we will test controller as soon as we recieve it.

That's fine, we will test controller as soon as we recieve it.

i have received and installed the controller you sent me. the problem now seems to be fixed and after 24 hrs the fridge is performing properly as far as i can tell. i wish to thank you for all the help, advice and prompt responses. i will be happy to recommend you to anybody with similar problems.

Well done, very pleased to hear all is now working correctly again.  If you have a moment, I would really appreciate it if you could leave a testimonial on the site as above.

best wishes,


will do