Klima Relay 1991 300D - DONDA ESTA? - PeachParts Mercedes-Benz Forum

Bengoshi2000 · #1 06-24-2021, 10:33 AM

Having a crappy summer with the AC on our cars...

Last week, the AC on my 91 300D suddenly quit. Compressor clutch is not cycling. I "puffed" the hi-pressure side connector and got a shot of freon, so there is some pressure in the system. I shorted the pressure switch at the R/D... nothing. Now I'm looking for the Klima Relay. I thought it would be behind the battery, but I looked, and it's not there. It's not anywhere along the driver's fender, either. I went over the entire engine compartment with no luck. I'm confident it's there but evidently I'm not visually acute enough to locate a relay with "KLIMA" written on it.

Can someone please point my blind arse in the right direction?

dieselbenz1 · #2 06-24-2021, 11:01 AM

Should be beside the over voltage relay behind the battery. Maybe easier to remove the battery.

123boy · #3 06-27-2021, 01:26 PM

Is there voltage at the compressor clutch connector? With the pressure switch "jumped" and the ac system "on". Any voltage at the compressor? Could the problem be "air gap" related?

Bengoshi2000 · #4 06-28-2021, 08:12 AM

Could be air gap related, but I’m trying to be methodical and start with the easy stuff…

When I get back from holiday I’ll dig into it more thoroughly.

123boy · #5 06-28-2021, 10:50 AM

The air gap is probably the quickest and easiest thing to check (no tools, meters, relays, wringing wiring, etc). Why not eliminate this very common and potential problem from your trouble shooting? As mentioned, if you have voltage at the compressor clutch and the unit isn't coming on line then your problem is one of only two things: The clutch is fubar or the air gap is excessive (only IF there's voltage present at the connector). If you're not sure how to evaluate the clutch operation/air gap, there are many links. You'll wonder why you didn't do that first.
Also worth mentioning, you stated that you "puffed" the high side. This only tells you there is pressure/gas in the system. You stated that you "jumped" the low pressure switch. That would be a good time to check the connector at the compressor and see if you've got 12 volt. The "other" connector at the r/d is for the condenser fan. Did you try jumping that one and did the fan come on?
These checks are done assuming "key on" and control panel configured for "cooling", of course. I believe the relays for the compressor and aux fan are on the driver's side fender well (not positive). Good luck!

Bengoshi2000 · #6 06-29-2021, 09:11 AM

I was just doing a quick check to see if the pressure switch was the culprit since I was leaving on vacation the next day. So I didn’t get into “full diagnostic mode.”

Been a rough few weeks car wise. It began in May when my son put RUG in the TDI golf. That touched off a cascade of problems that I sorted out literally 10 minutes before the ac died suddenly in the 300D.

Simultaneously out Honda Pilot would randomly drop into limp mode and engage the ABS system. I got that sorted and it’s ac decided to quit on the way to my father-in-law’s funeral. That turned out to be a bad high pressure side port valve. I tried put my r134a quick connect on it and the needle got stuck in the open position. I got a face full of oil/freon… I figure that shaved 2 years off my life.

Geez… sorry for the rant. Never rains but it pours…

123boy · #7 06-30-2021, 05:43 AM

YIKES! Sounds like you've got your hands full! One step at a time, I guess. I wouldn't worry about the "freon to the face", too much....long as you were able to keep it outta your eyes, etc.
When you're able and have the time this forum will be a great asset to help get your 300D sorted. That's for sure.
Be careful with those high side ports...

Bengoshi2000 · #8 08-10-2021, 07:13 AM

Found it exactly where y'all said, but mine wasn't blatantly marked "Klima." And if you aren't poking around with a flashlight, it's easy to miss! Or my eyesight is going...

Turns out the Klima relay was bad. Finally got my hands on a new one, now my ac is back. Just need to get the center vent pod replaced so I can get the air where I need it (vs. the defrost vents).

Does anyone know the part number for the plastic shield that covers the area behind the battery? Mine is pretty brittle and is falling apart.

123boy · #9 08-10-2021, 10:14 AM

Hey now, that's great news! Gotta be about the easiest repair....swap in a new relay. Glad you got your ac back. A great luxury and necessity (in the summer) that we often take for granted until it's not working. Good job!