on city driving, my car is heating when I have the A/C on... when I stop the A/C, everything goes back to normal... what could cause this?

 

It is possible one of the cooling fans isn't working. There are 2. One comes on when the A/C is running. To check this, get the car up to normal temperature (or if it is running hot) and see if both fans are on. If one isn't, that is your problem. If they are both working, I would think radiator (possibly) or thermostat(doubtful).

 

my car was doing that last month. It turned out that the cooling fan fuse (under the hood) was blown. replaced it and it works fine now (always stays at about 10 o'clock regardless). -C

 

well, I checked the fans this morning and I never saw the engine fan run, and the A/C fan did run when I put the A/C on, but after 5-10 mins, she was stopped... where is the fuse for the cooling fan??

 

it's in the main engine fuse box located at the top left of your engine compartment (when facing the motor). It's a 15A fuse if I remember correclty (or was it 10A). hth, -C