Looking for info to help a friend. A month ago an indie garage told them the climate control module on their 1994 940 was defective. A/C has full charge, A/C won't come on. Today was our first semi-cold (about 38 fahrenheit) morning. My friend noticed they have no heat. I do not know if the vent setting functions (defog, floor, dash) are working. Every post I've seen relating to climate control module failure has centered on lack of A/C, not lack of heat.
My question is this: Will a failure in the module also cancel out the heating function? Thanks in advance to one and all.
Richard
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86 740T/87 745GLE/96 960 Wagon

Richard,you need to let us know if the fan is turning in the dash when the heat is activated-turn it up-you'll hear it even if the vents are all closed.If the fan is not turning,it could be the module-or a fuse,other electrical problem.If the fan IS turning,then you have a vacuum problem-check as Spook has recommended-could be module (only ACC equipped cars have the vacuum solenoid resolder fix),vacuum motors or lines-see FAQ under "features".Hope this helps.
sredwine 94 940T 150K.

I know that the fan is turning, so that part works. I'm going to try and get a peek at it this weekend and check vacuum, etc..., as suggested. I'll let you know what I find. Thanks.
Richard
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86 740T/87 745GLE/96 960 Wagon

Dear Richard,

Good p.m. and may this find you well. Here are some questions to be answered:
(a) Is the vacuum hose to the heater control valve (between the engine and the firewall, slightly to the driver's side [US/Canada car] of center) attached to the valve, and if so, is the hose without holes, cracks, etc.
(b) Is the heater control valve in good working order?

If the vacuum hose has come loose (or is cracked) or the control valve has worn out, then it will not allow hot water to flow through the heater core.

The switch on the right side of the control module (marked in red only, or red-blue) selects the amount of heat (marked in red only) or heat/air con (red/blue markings).

If the A/C won't come on, and jumpering the pressostat (located on the accumulator, the can-like unit in front of the firewall, on the passenger side of the engine bay) activates the compressor, the problem is in the control module.

Specifically, the solder joints between the relay and/or the power connector - and the circuit board - have failed. This failure may be a break so small as not to be visible to the unaided eye.

See the FAQs (under FEATURES, above) for re-flowing the solder, to restore function. Only rosin core solder should be used (plumber's solder, acid core, will damage electrical/electronic devices).

Hope some of this helps.

Yours faithfully,

spook