94 GT (Modified) Overheats with A/C on

[mattsavage]

I have an overheating problem while driving when it is over 90 degrees outside when the A/C is running. The car NEVER gets hot when running without the A/C. My car is modified to a 347 Stroker, naturally aspirated. It has a relatively new cooling system with all components replaced including electric cooling fan. I believe that the fan turns on and runs, but when reaches a certain temperature, turns off. An example of this is when I turn the car on with the needle on the "L" of "normal," the fan turns on and cuts out after 30 seconds. Can anyone please give me an idea of what is going on? I can't but help to think that this is electrical or A/C related.

Thanks

Matt (gatorsvg@aol.com)

[dcarlson]

The car has a two speed fan. When it gets up to a certain temperature the low speed turns off and the high speed turns on. Is the high speed part working?

[StrokedStang]

You should have the fan wired to engage when AC compressor comes on.

[mattsavage]

I think the fan is supposed to turn on with the A/C compressor comes on, whether or not the fan kicks into high speed, i'm not sure. Something weird happens once in a while though....Sometimes I turn the key to the "on" position to accuate to fuel pump and the fan comes on at that point while the car is cold. Rarely happnes though.

[dcarlson]

Like I said, the high speed is supposed to kick on when the AC is on, or if the temperature gets above a certain point.

You said it only overheats when the AC is on. That sounds like when the high speed fan is supposed to come on it doesn't. Therefore you have no fan at all, since the low speed shuts down to let the high speed take over.

Try it. Let the car warm up with the AC off. Watch the fan. As soon as it comes on, turn the AC on MAX. If the fan shuts off, there is the cause of your overheating problem. From there you need to talk to a ford electronics expert or bring it to a technician to fix.

[mattsavage]

Thanks for the info. I'll have that checked.

[riverrat1952]

The CCM module controls the fan speeds and which speed the fan should fun. Do the test above and if the fan does not run on high speed you can push a straight pin through the wire and check for 12v to ground with a DVM. If voltage is there you have a bad fan. if no voltage you have a bad CCM module. I had the low fan speed relay in the CCM module go out on mine. Must be careful to not allow the pin to touch any metal. The wires and fuse on the fan circuit is big. Short will make a big mess.
Good luck..

[mattsavage]

After inspection/repair it appears that somehow the electrical fan connector (It's been replaced before) was for a V6, not a GT. How the hell that got on the car I have no idea. Apparantley it was pulling too much juice to the fan and the connector melted. It has been replaced with the correct connect and no longer overheats; however, it still get hot and causes the A/C to blow warm air. I am thinking of installing an auxillary fan.