MY 2003 BUICK RENDEVOUS HAS A PROBLEM WITH THE COOLING FANS ON THE RADIATOR. THEY WILL STOP WORKING EVEN WHEN THE CAR IS HOT /NEEDS THEM UNLESS THE A/C IS ON. IS THERE A SENSOR SOMEWHERE THAT REGULATES THEM THAT i COULD CHANGE OUT? WHAT USUSALLY CAUSES THIS. MY DAUGHTER HAD THE SAME MAKE AND YEAR AND IT DID THE SAME

I suspect you have a bad relay.........there are 3 relays that operate the two fans. You will need to test the relays to find which one. Find the relay box under the hood. On the underside of the lid, there should be a list of the relays and fuses.....locate the 3 fan relays. Note that all the relays (or most) are the same relay....if you have a meter check the relays. If you do not have a meter, find a relay that you can pull as a tester....a relay used for something you are not using at the moment...like the sunroof, or traction control etc. The fans run in stages controlled by the relays (all GM cars seem to have the same system) stage 1 = one fan runs, stage 2 = two fans run in series, so they are running at 1/2 speed, stage 3 both fans run at full speed.

Check the sensor on the high side of your air conditioning line i found oit that could be wrong with our fams not turning on and the air not working