Skip the auto shop - Our mechanics make house calls

Q: When A/C is on, the car overheats

asked by on

When the air conditioner is on, my car overheats; it only does this when the A/C is on. All the fans work well and the new antifreeze air pockets were purged from the system. I also replaced the plastic housing that attaches to the engine from the radiator hose. The check engine light is not on, but after driving around 3-4 miles the engine temperature rises over 240. What will fix these problems?

Engine overheating with AC on is generally caused by one of two possibilities. One, is increased engine load caused by a failing AC compressor. The AC compressor adds rotational load to the engine and if the compressor is wearing and becoming increasingly harder to turn this can cause engine overheating.

The second common cause is a cooling system not working efficiently. The AC condenser heats up as the AC is being used so the engine cooling system has to deal with this increased heat. Plugged or blocked radiator condenser fins, fans not working efficiently or a water pump that is not circulating coolant could all cause overheating with AC on only.

One last possibility though more unlikely as the vehicle would generally read hot whether the AC is on or not is a faulty engine coolant temperature sensor. The coolant temp needs to be read out with a temperature gun and needs to compare with the gauge. The radiator and condenser fins should be cleaned of debris. If these items do correct the issue, then you may want to enlist the help of a mechanic, such as one from YourMechanic, who will have the expertise to diagnose and correct the overheating issue.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Can I add radiator fan?

The engine compartment of a 2011 Dodge Grand Caravan is not as big as older vans used to be. As a result, fitting an auxiliary fan to your radiator in an effort to make it run cooler might be difficult....

Q: How do I use the rear window defogger?

The rear window defogger is a key safety feature. It helps eliminate moisture from the rear window to give you better visibility. To turn on the rear window defogger, press the rear window defogger button, which is located alongside the...

Q: Oil sensor in car is turning on and off 2014 Volkswagon Beetle

Hi - this is not normal, and is most likely a loose connector at the temperature sensor. This sensor will be screwed into the lower oil pan, which can by nature be a fairly oily area, making good electrical connectivity...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.