If your car is working properly, turning on the air conditioning (A/C) should not cause the engine to overheat. The engine and cooling system are designed to handle the additional stress created by the A/C system under normal conditions.
Problems only occur when there’s an underlying issue with the cooling system or (in some rare cases) the A/C compressor, as we’ll discuss below.
Why Does My Car Overheat When the A/C is on?
When you switch on your car’s A/C, the A/C compressor turns on to push refrigerant through the system. Because the compressor is driven off the engine by a belt, it puts an additional load on the engine. Also, the temperature of the A/C condenser, which sits right in front of the engine’s radiator, increases when the A/C is turned on.
Under normal circumstances, the demands imposed by the A/C system will not cause the engine to overheat because fan(s) automatically turn on to keep things cool. However, if the cooling system is already having problems, engaging the A/C may push the engine to the point of overheating.
Common cooling system problems that can lead to overheating when the A/C is turned on include:
- A weak water pump
- An obstructed radiator
- Cooling fan(s) not working properly
- Faulty engine coolant temperature sensor
Also, although somewhat rare, a bad A/C compressor that’s difficult to turn can put an additional strain on the engine, potentially resulting in overheating.
Overloading the car is another possibility. For example, if you’re towing a trailer that’s well beyond the vehicle’s rated capacity, overheating may result when the A/C is turned on.
Related FAQ
Under normal operating conditions, turning on the A/C system will not make the engine run hotter. When the A/C is activated, one or more cooling fans turn on automatically to provide additional airflow and keep things cool.
No, you definitely should not turn on your car’s A/C if the engine is overheating. The best plan is to pull over, turn the engine off immediately, and arrange for a tow truck. Allowing your car to overheat even once can cause extensive engine damage.
If you must continue driving for whatever reason, turn the A/C OFF and the heater ON. Turning on the heater will draw excess heat through the heater core (a type of radiator), causing the engine coolant’s temperature to drop slightly.
Keep in mind, however, that the engine can still overheat with the heater on, so you’ll need to monitor the temperature gauge carefully. Also, the heater trick usually won’t work if the system is low on coolant since there isn’t enough flow through the heater core.
There’s something wrong with your car if the engine is overheating when the A/C is switched on. You (or your mechanic) will need to do some diagnostic work to determine the root cause of the problem.
Once again, allowing your car to overheat even once can cause internal engine damage, so you’ll want to address the overheating issue immediately.
How to Get Quality Replacement Parts if Your Car Overheats
As we’ve explained, there are a number of possible reasons your car overheats when the A/C is on. Overheating is a serious issue that can lead to a warped and damaged engine. A trusted mechanic can narrow down the list of potential causes and help you find out what parts need to be repaired or replaced. Once you know that, you can trust CarParts.com when buying replacement parts.
CarParts.com is dedicated to helping you find the best deals online for auto parts. That’s why we offer a price match guarantee and a lifetime replacement guarantee on the products in our catalog. Purchase with confidence knowing that we even offer a 60-day return policy. The wide range of parts in our catalog are available at various price points, and all come from trusted aftermarket brands. Best of all, placing an order takes just a few clicks, all from the comfort of your own home.
Place your order for a new water pump or other parts on CarParts.com today.
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