I have a 1994 940. The A/C has a hard time cooling in stop and go traffic or while stopped. The vovlo mechanic said that the fan should be running most of the time the A/C is on. My fan cycles on and off. On for 10 seconds off for 40. Then again. If it gets hotter out it will stay on a little longer then go off. I changed the thermo control switch in the radiator. It didn't make a difference. Now I am wondering about changing the pressostats? Will they help keep the fan on longer? I grounded the high and low pressostats and they turned the fan on until I took the ground wire off of them. I have never heard my fan come on high before I did that. If I replace the high and low fan speed pressostats will this help keep the condensor cool? Or is there something else I am missing? The relays seem to be kicking the fan on and off.

Thanks.

Dear D.J.,

May this find you well. The fan relay - located just behind the passenger-side headlight (USA/Canada models) - controls fan speeds, in response to coolant temperature.

I believe this is a dual-speed relay. Thus, one of the two switches inside the relay, that which controls high-speed operation, may have failed. As a result, the fan runs only in "low speed".

Posts indicate that intermittent operation - that is, on-off, on-off, etc. - is how the fan is supposed to work, except in the highest-stress situations.

You should be able to get a fan relay at a salvage yard, at low cost.

Yours faithfully,

spook