Hi everybody,

I apologize for the claiming my post is more urgent than others, but I only got back from Kuwait about 7 weeks ago and now I leave for China next Tuesday night and I won't be back until late June 2013.

So... I've been trying all summer to get my daughter's AC working.

• Flushed the condenser and evaporator (both directions) until fluid was completely clear. For evaporator, I used a drilled out txv for flushing.
• Installed all new hoses, seals (used Nylog), dryer, txv, compressor (not rebuilt).
• Tested for leaks: vacuum 29" and dry gas pressure @ 200psi (24 hr each)

Here's where it gets weird...

As I got 2/3 of the charge in, the pressures were 30(L) and 200(H), the vents were blowing cold air. The condenser fan came on and then after about 1 minute, both the compressor and the cabin fan/blower kicked off. The condenser fan continued to run. The first thing I did was look for a blown fuse and when I removed the climate control fuse (about 3-5 minutes later) the condenser fan kicked off. Nothing related to climate control has worked since then.

The system is still holding its charge, but I can't get the cabin blower fan to come on in either heat or cool mode.

Using my '82 parts car, I've swapped the climate control module, both of the big "relay" modules above the glove compartment, the relay on the driver's fender well and numerous other relays. I've also replaced all fuses - just in case.

Please, please... any ideas???

Thanks!

__________________
Brian

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Sometimes the only choices you have left are bad ones.
Agent Broyles (Fringe)

Oh, and after neither climate control module worked, I resoldered all suspect solder joints. (There were a few in each module.) And with my degree in electronics, I left no cold solder joints.

Unfortunately, that didn't resolve the issue.

__________________
Brian

_________________________________
Sometimes the only choices you have left are bad ones.
Agent Broyles (Fringe)

Climate Control Vacuum Supply?

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

Didn't think of that. Would that cause the electrical parts (compressor & blower) to be inoperative?

I'll go check it now just in case.

__________________
Brian

_________________________________
Sometimes the only choices you have left are bad ones.
Agent Broyles (Fringe)

I have had ignition switches get flaky and cause these symptoms. It might be a long shot, but wiggle the ignition switch while it is in the engine running position.

Another thing that doesn't match your description perfectly, but needs to be checked anyway: pull the glove box liner and make sure that there is a hose running horizontally to the connection on the temp sensor that is under the little square vent in the middle of the dash.

Hope this helps.

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

Annoy a Liberal, Read the Constitution

Thanks Larry, sorry I didn't mention earlier, but the (new) hose is intact and I did try the ignition switch but there was no sign of flakiness (and it was changed about 3 years ago).

EDIT: It was not this car that was changed. It was my '82.

Ok, so I just checked the voltage at pin 12 to the climate control module. It is dead. I verified that the fuse #8 is not blown, but there is no voltage at either side of it.

So... it is looking more like the ignition switch. Unless there is another fuse or relay between the climate control and the ignition switch(?).


Oh, does anybody know the function of that module that sits on the hump under the ashtray?

__________________
Brian

_________________________________
Sometimes the only choices you have left are bad ones.
Agent Broyles (Fringe)

Brian,
First I want to THANK YOU for your service to our country.
I don't have a 123 and have never worked on one but I have a lot of experience on the gen 1 126 cars so what I say may not apply to your car.
If the car has an air bag then the module under the ash tray may be the controller for the air bag. They are usually placed on the hump. On the gen1 126 the compressor and fan are separate circuits except for power and ground. If both went out at the same time then that is where to start. I know you have checked fuses but on the 126 the fan gets its power from an external (to the fuse block) strip fuse. It is in a little black box about 1 1/2 in long and 3/8 in wide. The strip can break in the center but look good. I would put the control panel in defrost mode until you find the problem. Defrost mode needs no vacuum, puts the fan on high and compressor on but full heat. Hot air should come out the defrost vents. Are any other systems like turn signals, radio, lights, windows, seats, etc not working? Maybe that would be another clue.
Paul

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84 500 SEL (307,xxx miles)

Well, it turns out it was the ignition switch after all. Kudos to Larry! I took the old one apart and can't see any signs of a defect, and I still have something squirrelly going on with the wiring. With the car running... When I'm messing around under the dash (drivers side) the buzzer starts and/or the glow plug light comes on. But AC hasn't malfunctioned since the new switch went in. (Vent is only about 15F below ambient so next step is to clean evaporator.)

Thanks everybody for your help!!!

__________________
Brian

_________________________________
Sometimes the only choices you have left are bad ones.
Agent Broyles (Fringe)