I posted previously, that the hvac was putting heat out of the dash vents. On, off, low, high, doesn't matter. The car just keeps putting out heat on low setting. Someone posted to test to see if we get 12v. My mechanic only had a few minutes to look at it today based on what the people on the forum said. He checked that, said he did not get 12 volts, but he said I should have clarified something. He feels the heat is only coming out of the DEFROSTER vents, not the dash vents. Air is probably just leaking out of the defroster vent and into the dash vents due to leaking pods. So he thinks the hvac has gone into a mode where the climate control won't engage at all, so the car then defaults to defroster mode.

Does that make a difference in any diagnosis? I'm only posting that here as a new thread because the old one is based on a flawed into. This can be merged later with that post.

Also, are climate controls from a 1995 300 compatible with the earlier models? The numbers are 124 830 18 85 for the earlier models and 124 830 31 85 for the 1995 models. They look the same.

1991 300d, 233k

Your diagnosis is still exactly the same. If your pushbutton unit or the fuse feeding it is dead, you'll be in a default defrost position.

You might need a new mechanic.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

My mechanic is great but he didn't have time to look into it completely today. He only had time to read the end result posted previously that I gave him and to check for the 12 volt or not. Since there was no 12v and you're saying it's then the push button unit, is there a feasible way to fix the push button problem, or just source a new climate control? I saw an article online where they say it's typically a soldering issue where it gets old and you have to resolder it, but that's too much time and work if that's the case.

The 124 chassis repair manuals are at this link

https://www.startekinfo.com/StarTek/outside/12264/?requestedDocId=12264 You will have to do this on a Windows machine that has Adobe Flash enabled.

There is a step by step procedure for troubleshooting the climate control. It asks for a special breakout box that goes between the climate control and the wiring harness. However it is possible to use the wiring diagram (also in this document library) to figure out what the test is asking for, and just go right to the pins on the climate control connector with your meter.

If you're anywhere near Columbia SC I may be able to help you.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

I replaced the entire climate control with a used part and it's working now. I wonder if there's an easy fix for the climate control so I can sell it off on ebay as a working unit.