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Old 09-14-1999, 09:00 AM
Joey Salisbury
Posts: n/a
My climate control seems to have a mind of its own. Sometimes it works - sometimes it don't.

Old 09-14-1999, 11:03 AM
Posts: n/a
Starting from the beginning...

- what car?
- what year?
- type of climate controls? - auto vs manual...
- what part of the climate controls? - blowing hot/cold air, A/C or not, not blowing at all...


1982 300D -

Old 09-15-1999, 11:02 PM
Joey Salisbury
Posts: n/a

- what car? 300TD
- what year
- type of climate controls? - auto vs manual... auto
- what part of the climate controls? - blowing hot/cold air, A/C or not, not blowing at all... defrost always will work; a/c and vent is intermittent
Old 09-16-1999, 09:04 AM
Posts: n/a
Hello again.

Sorry if the previous post seemed rude. Just needed the info... :^)

The auto climate stuff is a mix of vacuum to activate the various things and a control module (brain) to tell the vacuum what to do. I would guess that it's the control module. The vacuum would not be intermittent or would disable particular functions all the time (the lower vents don't open on my car, for example... :^( ). The fact that the defrost works seems confirm it: defrost doesn't think, it blows air at the maximum setting as hot as possible.

I remeber reading about control module boards that would crack and create intermittent problems with connections coming and going. Might be what yuou have.

I guess the folks here can give you more info on all this.


1982 300D -

Old 09-16-1999, 10:23 AM
Joey Salisbury
Posts: n/a
Thanks Nick

Now I have a place to start.

Old 09-16-1999, 10:32 PM
Registered User
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
The thing about these systems is that if one of the vacuum elements does leak, it could cause many differnt funcional problems. You can test them all at the vac switch block. if they all check out then go to the control unit.

1987 16V

Old 09-18-1999, 11:39 PM
Registered User
Join Date: Sep 1999
Location: Miami, FL
Posts: 645
I also have a problem with my climate control. At first, it would blow hot air every so often when the AC was on. It would stop after maybe 45 seconds and blow cold air again.

Now the blower has ceased to blow, except unpredictably every several days or so. Hot air comes out of the side vents, not the center vent. When I am traveling over 30 mph, the defroster emits warm air.

This is on a 1990 300D 2.5 Turbo. Another problem is that the power window switch on the console for the LR window does not work. The window will come down with the switch on the LR door.

How do I check the blower circuitry and fix it/replace it and how do I remove the power window switch? Is this info available in the latest Haynes Manual?
Old 09-20-1999, 12:49 AM
Larry Delor's Avatar
What, Me Worry?
Join Date: Jun 1999
Location: Sarasota, Fl.
Posts: 3,114
Does the compressor come on when it is supposed to?

'83 300D-T
Old 09-20-1999, 11:06 PM
Registered User
Join Date: Sep 1999
Location: Miami, FL
Posts: 645
When the blower comes on, the compressor seems to come on. When the blower doesn't come on, the compressor doesn't come on. Since the blower only comes on occasionally, I haven't been able to check whether it is on when the blower is working. The air coming out is cooler than the ambient temp. when the blower is working, but the fool thing cuts on and off with no real motivation to do so. This happens when I am in traffic and can't pop the hood.

When the blower ISN'T working, the compressor is not on, and the faster I drive, the more hot air comes out of the defroster vent and the side vents on the dash. I understand that the heater is on by default.

I have checked the fuses and all are okay.

The problem seems to be in the climate control thingie. Blower motors on other cars I have owned have made weird screeching noises or become sluggish when they have decided to go out. This one either blows well, or doesn't. Anyone know where the climate control is? I suspect it is under the dash someplace. It isn't accessible from under the hood, so far as I can tell.

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