1999 E430 - A/C Climate Control Module - Limited Access to Diagnostics and normal functionality .....
My Pop has this vehicle. He has already had to (in the past) top off the a/c charge of 134a, successfully. But recently decided to fix the leaks (replaced both high side / low side tap valves) and vacuum down and recharge his A/C system. Probably done this a 1000 times over the years with various cars. But since he had a time getting the compressor to kick in so he could finish the charge, my brother attempted to follow instructions from this forum to “force” the compressor to ignore temp & pressure sensors. He made it to the menu which allows changing the values, but could never get any further, as the control interface now has become partially unavailable. (Yes, I now understand that all needed was to clear the codes and the compressor should/ would have kicked in like normal....but now my ODBII scanner cannot access the aircon module , see codes on it, or clear them)
I’ll now elaborate on the limited access.
Now after starting the car, you can no longer make temperature adjustments, the defrost button, recirc button, EC button, are all not working. The fan control, rear defrost button, I think are the only available when the car is started. You can only either get into a partial diagnostic mode which will display the P1 (cannot toggle to others using left “auto” button, cannot adjust values using either fan control or up/dn temp control arrows). You can only access one of the sensor values #1. And the only way to change the temp on either zone (dual zone, BTW) is to turn ignition to off, press the REST button, then you are able to change the temperatures on either left or right zone.
I have tried repeatedly to “reset” the climate control system. I never make it to step three. I think since I cannot control the temps, with key on (position 2, engine on or off), and make the proper adjustments on both zones, prior to cutting ignition off, then back on and holding two buttons down until they begin to flash (they NEVER flash), that this procedure is unable to be executed.
Here is my question:
My Dad told me that prior to my brother’s“attempt “ to add an override so the compressor would ignore the sensors and kick on (which was never able to be fully implemented),that the clutch engaged on compressor just fine, and system would freeze you out. So I don’t think it is a failure of the clutch coil. It was just working prior to the Freon recovery/ evacuation, replacement of line taps, pump down and attempted recharge. I’m betting the computer was simply registering a low pressure and or temperature and through a fault which wouldn’t allow the compressor to kick in and allow my Dad to finish charging the A/C system. So, the question is,
How do I get this climate control module back to a factory system state so it will “operate” normally? (Oh and already tried removing power for a while, but I figured like a PC, it probably has a button cell battery on the CCM, which is probably why that had no effect).
My Pops is a retired mechanic, and the computer stuff throws him a bit. He’s old school. My brother is mainly a auto glass installer who seems to be able to do anything mechanical. I’m a software engineer and information systems manager. You would think this would not have the three of us scratching our heads. But in computers , I have had to deal with PLC’s, industrial machinery, access control systems, as well as obviously computer programming and systems administration. So I would think a simple thing like this would not give so much headache.
I can’t simply admit defeat. This is my father’s dream car, he’s only had it for about a year, and he cannot afford to take it to a dealer (pride is probably a part of it too). It is Father’s Day today, and I would love nothing more than to fix this for him. Any help would be a blessing.
TIA,
Brent
