I am experiencing MAJOR problems with my Climate control. The heat is always on (through defrost vents) and there is a constant clicking coming from inside the cabin on the passenger side. When I parked my car today, I shut the engine off and one of the aux fans kept running...the car was not hot and the engine was off!! I had to get under the hood and disconnect the fan itself.

It wasn't this bad yesterday, and I'm afraid things will only get worse.

You have no vacuum to the climate control (vac line up on top of the brake booster) or the servos are all bad (unlikely) OR the vac supply line is off at the switchover valve -- have to pull the glove box to check.

Full heat all the time may be a bad CC pushbutton control unit, too -- but check the sampler fan for operation first. A small bit of tissue must stay on the little grille up by the sunroof switch with the CC running -- if not, either the fan is loose on the hose (like the one on the TE was) or bad, and not pulling air over the temp sensor behind the little grille. This will cause the CC to switch modes constantly (the clicking).

I'd also get some contact cleaner and remove the CC pushbutton unit, then spray down the temp control wheel rheostat with it while working the wheel up and down -- dirt, sprayed soda (as was my case), slipped coffee, etc will cause the temp wheel to make intermittant contact.

If the temp was out of control (way cold, then way hot) before this happened, likely the fan motor for the temp sensor was failing or loose. It's underneath the passenger side air vent, remove glove box to access.

Your fuse could also be corroded, so you don't get good voltage, too 00 this will cause intermittant or erratic operation, no fan control, and heat out the defrost vent only.

you may also just have a bad monovalve, so the heater core is hot all the time, You can clamp one of the heater hoses shut and see if that helps, but if you have only defrost air flow, fix that first.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I have noticed that my CC does cool the car initially at start-up...but after reaching normal temp, the clicking starts up again...and even more persistent than before!! At that point, the heat is on full bore and the CC control panel will not work at all.

Checked the temp sensor vent and that is pulling sample air. Also checked the vaccuum hose, and that is fine. Plan to pull the CC pushbutton unit (is it complex??) and clean it with contact cleaner. How ironic is it that most of the summer in Chicago has been cool...but now as it is hot in September, my ac is not reliable...and I get only HEAT!

UUGGH!