w124 300E Climate control problem - PeachParts Mercedes-Benz Forum

mbnz · #1 05-21-2009, 04:58 AM

I have a problem with my heating/ventillation/ac in that the air only comes out of the vents very low. It doesn't matter if I have ac on or heat or EC or defrost. Even if the fan is on low or medium or high, the air comes out of the vents very low (less than normal low).

A few months back, when the days were colder, it was working fine when I first started the vehicle, everything worked fine as I drove it. But once I shut the car off, finished my shopping (about an hour or more later), the climate control wouldn't work properly, the air would not come out full blast, it would only come out very low.

But, now it will only come out very low even when I first drive it.

I checked the fuses and they are fine.

Also, sometimes at night I noticed some of the climate control lights (like recirculation) and the shifter (P DRN) Lights will flash. I first noticed this a year ago, but the climate control was working fine then. Also, the temp round dial and the first 3 ventillation switches (from the defrost going to the passenger side) do not light up at night anymore, this first happened about the same time as the flashing lights problem but started working again, but last 6 months they aren't coming on anymore. Not sure if this has anything to do with it.

I have a 1990 300E 3.0L , what are some of the things I should look for? and any idea of the costs?

I will have to take this in to a shop, but I would like to have some knowledge before I do.

thanks.

mbdoc · #2 05-21-2009, 08:15 AM

Checking the command signal from a/c pushbutton to the blower regulator would be my starting point.

That voltage checking point is next to the brake booster under hood.