Why Does My Car Overheat When I Turn The Airconditioner On?

The engine cooling fan clutch or the electric fan could be broken. The engine-cooling fan moves air through the radiator when your car is stationary or travelling at a slow speed. This air removes the heat from the coolant created by the engine, using the radiator as a conductor.  When the cooling fan no longer works it causes the coolant to overheat which causes the engine to overheat.  Listen for a noise like a whirring sound or signs of a leak.  If there are any signs of this then the cooling fan clutch may need replacing. To find out if the electric motor cooling fan is working start your engine and spin the fan blade if it does not move and feels stuck then it will need replacing. 
Another troubleshooting solution can be seen when you start the engine, turn your air conditioning on, if the cooling fan does not instantly activate then check the fan motor fuse, if the fuse is OK then you will have to check the whole of your electrical system.  If you do not feel confident that you can do that it would probably be best to get it checked by a qualified mechanic.  If you feel you would like to fix it yourself, then you will need a wiring schematic, which you will find in your repair manual. Trace the circuit through the relay components and the fuse, if everything after the tests are ok then the fan motor has failed and you will have to replace it. The biggest culprit of overheating is when the cooling fan has broken.

When you run the air conditioner it puts an additional load on your car's engine.   This makes the engine work harder and create more heat.   It is very unlikely that there is a problem with the air conditioning.   The problem is more likely to be in the cooling system (radiator, antifreeze, thermostat, etc).   If you have never had the cooling system flushed and refilled with new antifreeze that is what I would do first.   If your air conditioner compressor is bad it is unlikely that it will produce cold air.   Replacing the compressor is the LAST thing to try in your case.

My car is doing the same thing.   It gets really hot on hwy 5 or on trips to like sacramento from where I live, and/or if I run the AC.   Which considering the tip I see above and my gutt telling me that it might have something to do with the fan, I think I may have found my solution.  

I drive a 2004 Ford Focus SVT and it can get hot because it is a fast car and I thought I was just driving it too hard.   Anyhow I am going to check to see if the radiator is clogged or if that second fan is coming on.   I'm hearing a high pitched noise when its real hot like that and it could be possibly the fan is trying to spin?   Who knows, but I think I'm on the right track.   Before I spend all kinds of money for the mechanics to identify the problem.  

For the guy with the 95 mustang.   REMEMBER you can't just stick straight WATER in your coolant system.   Water boils at a much lower temperature than the Anti-Freeze.   A common mistake made by some.   Just in case.   Make sure your using a 50/50 mix when your adding water on the side of the road like that.   I always carry some in my trunk, with oil, etc etc....

It could also be that if your car has a 2nd or separate radiator fan that should come on when the car is either hot OR when the A/C is on - perhaps it is NOT coming on and thus your car overheats. If your car does have a 2nd fan, check to see if it is coming on when you turn on your air conditioner.

Also, I would check that your radiator fan is on (even if it has only one electric fan) when the car temperature is getting near the HOT zone. At some point, the fan should come on to help circulate the air through the radiator vents and help cool the coolant (water) in the radiator.

In short, make sure your fan(s) are working okay. If not, that could be causing your car to overheat too.

My car started overheating to day when I turned on my air conditioner and smoke started coming out thru the dashboard. What could it be

I have a 95 Ford Mustang. I just replace the air compressor 15 days ago just yesterday I went for a short drive turn off the car and the water started boiling over in the plastic reservoir.Once the car cooled I added a little more water and I let the engine get hot I turned the air conditioner on the fan comes on as well now the car didn't overheat so I drove it about 6 mile and everything seem find now.What do you think?

Check the thermostat

My car is overheating when I turn ac on

Defective air-con fan relay, or circuit from relay to radiator fans is open or your radiator fan is broken.Yeah, Also could be a defective thermostat. If engine only overheats when air-con is turned on same answer on stated on first sentence.

Have you looked to see if thermostat is working or if your radiator is not plugged up

You probably have a bad thermostat or you my just need a good radiator flush

If your car is getting Overheat When you Turn The Air conditioner On,it means that you need to repair your compressor or it will need to be replaced.

If your car overheats with the A/C on and temp is fine with the A/C off
you might want to check the A/C clutch. I just had this problem on a '98
Civic.

I replaced the thermostat, coolant temp sensor and jumped the
wires to the coolant fan (A/C fan worked fine) to see if it worked.
(Cooling fan was not operating as it should.) Replaced parts didn't
solve problem and the fan operated fine with wires jumped.

I took the
car to my mechanic and he noticed the A/C clutch was not engaging as it
should and causing the ECU to throw out all kinds of check engine codes.
I guess it might have been OK to just replace the clutch, but we
replaced the entire condenser as well as the accumulator.

This fixed the
problem... Cooling fan began operating as it should and engine quit
overheating. You should look into this being the cause of your problem.