W124 Climate Control Issue - HELP! - PeachParts Mercedes-Benz Forum

zeronero · #1 09-13-2007, 04:02 AM

What's up, haven't posted here in a while because I've been away from my car for a year while living in Europe. While in Europe my car, a '92 400E with 210,000 miles was stored at a family members house, only getting driven less than 50 miles for the year! Upon arrival all I needed to do was put in a new battery and some transmission fluid and it started right up and drove perfectly.

Currently though, the car does have some minor issues, but this one, the climate control issue is the one that's most important. Until about a week ago the climate control was working fine, with exception to the fan, it's has some minor squeaking noises which means that it will eventually go out, but it still works fine.

The exact issue with the system is that when on A/C mode and Economy mode the doesn't blow, but when on Defrost mode it works fine. When on the freeway the in A/C mode I can feel cold air come out of the vests through the suction of speed of the car, so that's all working fine. But just to make it more difficult the economy mode sometimes works when the heat comes out, bizarre.

This started when I was on the freeway in traffic when it was about 90 degrees out with the A/C on, before I knew it the A/C went dead and the temp gage on the car was in the red. I turned the A/C off and the engine temp slowly went down, once I got back up to freeway speeds the temp was back to normal, but when I turned the A/C on cold air was coming out of the vents but only because of the suction, not the blower motor. The engine temp hasn't been an issue since.

From what I can tell is that for some reason the blower motor sometimes works and sometimes doesn't, but I have no clue what it could be from. I really don't think it's the control unit, so that only leaves me thinking it might be the gates in the ducts being jammed or something but I can hear them move when I hit different modes, so I think they're all working fine. I've got no clue.

So, if anyone has any knowledge they can lend I would greatly appeciate it!

TheEngineer · #2 09-13-2007, 10:55 AM

Your car has a diagnostic terminal near the battery. Obtain a reader and start there

saumil · #3 09-13-2007, 08:02 PM

Intermittent blower operation could generally be due to:
1. bad contact in the ignition switch - check and see if the contacts are good, otherwise replace
2. intermittent blower motor itself
3. the climate control unit could either be bad or is receiving bad information from cabin temperature sensor

zeronero · #4 09-17-2007, 03:40 PM

Well, I think i'll remove the blower motor when I have some free time, I'm thinking that might be the issue.

dlssmith · #5 09-17-2007, 06:50 PM

I'd bet on blower motor brushes and/or bearings. Sitting for a year probably didn't help them. When they are worn the motor just doesn't want to start spinning.

david s poole · #6 09-18-2007, 10:55 AM

check the blower fuse,it's in a small rectangular black container under the hood on drivers side.they are famous for cracking in the centre and making intermittent contact.

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