climate control

[nutco]

The climate control on my 1997 940 has started to play up,when you turn the key to position 1 or start the car up, makes no difference the fan starts up, when you turn the fan knob to Auto the fan runs very slow, switch it to 0 and it speeds up a bit, switch it to 1 to 5 and it runs at 5,you cannot turn the fan off, The center direction knob does not seem to move any of the flaps as the air seems to come out of most of them,I have tried moving the knob but cannot hear the flaps moving), The right hand temp knob is working but when positioned to hot blows cold and as you move the knob towards cold the warmer it gets until you reach cold when its blowing full hot,I've taken the unit out but as it has a unit like a radio, im not sure where to start, anyone had this kind of problem and can suggest a plan of action, ta

[Forrest]

Have you got any fault codes stored in the ECC? Procedure for reading them here.

https://www.volvoclub.org.uk/faq/Hea...iagnosticCodes

[nutco]

Hi Forrest,
I have tried what you suggested but I dont get any flashing from the A/C button when testing, it is total off, outside of the testing sequence its constantly flashing show a major fault, I may pull the unit out and re solder all the joints as mentioned it may cause faults,

[Forrest]

If you cannot pull the codes there may well be a problem with the ECC unit. I’d be more inclined to try to source a known good unit but ECC for the 940 was quite rare (they are not the same as the 960) and could be expensive and hard to find.

The only problem I’ve actually encountered with the soldered connections inside one was with the large a/c relay in a non-ECC unit.

There may be more than one fault. I think there is a separate power-stage/resistor which controls the blower speed. It may be hard to determine if that is getting garbage instructions from the ECC or is failing in its own right.

Good luck getter to the bottom of it.