W124 climate control question - PeachParts Mercedes-Benz Forum

BENZ-LGB · #1 04-20-2007, 03:18 PM

I own a 1991 300CE that I recently purchased. The car has nearly 125k.

Since I bought the car the A/C, front defroster and heater have always worked fine.

Today, however, when I pushed the defroster button I got nothing, zilch, nada. I pushed all the buttons and the same thing, no defroster, no A/C, no fan.

A few minutes later, after driving about half a mile (and the windshield begining to fog up)--air began to flow and everything was working as it should. The climate control is now working fine (at least for the time being).

This is the first time the the coupe has done that and, in fact, it is the first time that any of my Benzes have done that.

Any ideas on what the problem may be?

At first I thought it might have been a bad fuse, but then when everything came back, on that theory was shot down.

Is it a bad climate control unit?

Any suggestions would be appreciated.

BTW, the only thing different about today is that it is raining (a rare occurrence this year in otherwise sunny So. Calif.).

Thanks.

Addbhp · #2 04-20-2007, 04:18 PM

I had the exact same experience two weeks back with my 90 300e. I replaced the 30 Amp fuse, it was cracked but even after fixing that I am still with out the use of the climate controlls. I started a thread not too long ago about this and I've narrowed it down to either the control unit (with a volt meter you can test for this- how is explained in my previous thread) or the resistor that lies under the blower motor. Don't want to replace both as that is expensive. I am hoping to test the relay this weekend and determine next steps. I've actually been too busy and the weather has not cooperated with working on the car. Let me know how you make out as our problems are identical.
Good luck
Mark

Addbhp · #3 04-20-2007, 04:30 PM

If you search "W124 Heater Woes" this is the thread I started.

BENZ-LGB · #4 04-20-2007, 06:05 PM

Thanks.

I looked at your thread. Same symptoms (or I should say symptom, since so far it has done it only once) as mine.

Intermittent problems are a PITA to diagnose.

What I am going to do is wait until it does it again (hopefully that would be never, but you never know) then I will swap the climate control unit with the unit from my 300TE. They are identical.

I'll see what happens then!

In the meantime if anyone has suggestions and/or ideas (or if you discover the source of your problem) please post ehre.

Gracias!

Carson357 · #5 04-20-2007, 06:29 PM

with car and climate control on try turning the key back to the left very slight and see if it then runs, if it does the ignition switch may be faulty

BENZ-LGB · #6 04-20-2007, 07:12 PM

addbhp...check the link below. The symptoms sound like the symptoms exhibited by our cars.

Maybe it will save us both some potentially expensive repairs.

http://mbca.cartama.net/showthread.php?t=4033&highlight=fusable+link

I am going to look at the one in my car as soon as I get a chance.