Dreaded HVAC Question
 

Hello All,

Been lurking here for a couple of months, but now I need help.

Some background, I recently bought a 84 W123 280CE imported from Germany by a local used car dealer. It has 160,000 Kms and is in excellent shape with stamped books upto 120,00 kms the second owner didn't keep the book up but I have some reciepts and TUV inspections to present.

A month ago I converted to R134a since we don't have much choice here in British Columbia, everything has gone reasonable well except one small problem that was present before the conversion. Three times now, once before the conversion and twice after, the compressor clutch will stop activating. The two times before it has started again after a period of time. The first time was a couple of weeks and the second was a matter of hours. Today we hit about 30 degrees and in city traffic it did it again, and has not come on again.

I have checked the fuses and unplugged the relays on the right fender and gave the plug a bit of a clean, but it's hasn't done anything.

I'm not much of DIY when it comes to electrical, so I will have to take it somewhere, however I like to be armed with some idea beforehand.

I didn't have the conversion done by Mercedes but by an independent, but since the problem existed before hand, I can't expect them to cover this problem, however, if I'm getting into electrical HVAC stuff, would I be better to go to the dealer now?, or risk an independent replacing parts until he finds the problem?.

I will be glad of any suggestions or thoughts on this, Thanks

BTW It's the simple Euro system, not the Climate Control, I guess I'm lucky in that repect from what I've read.

This is guesswork but, I'd look hard at activation and control circuits for the clutch. The posible players are relays, high/low pressure switches and temp switches for coolant temp. I know the 103 US/federal version has a 2 pole switch in the head for high speed aux. fan and clutch cutout.

I'd also look to see if the "thermistor" in the evap has electrical control. Some generic systems have one that is adjustable for clutch shutoff at certian temps.

There are also some compressors that have rpm sensors in them that if bad will cut the clutch and they are intermitent.

Hope this helps,
Joe

Fixed!
 

Took my car back to the guy who did the conversion, chedked everything out, found the inline fuse holder from the battery was loose, one quick snap and cold air again. Boy wished all problems were that easy. anyway thanks Joe for your help

Wayne.