Q: The car is overheating and hissing when the AC is on

asked by on

My car has started to overheat lately. When I drive with my air conditioning on, I start having problems if I come to a stop light for instance. The air turns from cool to warm and the hissing noise can be heard. Then, the engine starts overheating. I checked the level of coolant and it's fine. When I stopped my car in the traffic recently, it began to overheat but I pulled over and waited for it to cool down. Then it ran fine again. What could be the issue? Thanks.

Hello, if the car is only overheating when it is not moving then it is usually caused by an air flow issue through the radiator. Most of the time, this is caused by an issue with the radiator fan not coming on.

To diagnose this, I start by starting the engine and allowing it to warm up. As the engine starts to overheat the fan should come on. If it doesn’t, then the fan and the circuit need to be checked. Most of the time this is caused by a bad fan or fan relay. If you need to have this fixed, consider having a certified mechanic come to your home or office to diagnose your overheating problem accurately.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 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!
  1. Home
  2. Questions
  3. The car is overheating and hissing when the AC is on

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: Q: Car overheats

Overheating is a fairly common issue with many vehicles. The most common cause of an engine to overheat would be a coolant leak. If a leak exists, the engine will not have enough coolant to keep the temperature within specification....

Q: no acceleration when pushing the gas pedal down (even to the floor)

This may be related to a faulty mass air flow sensor or potentially a bad throttle position sensor. The mass air flow sensor monitors air as it enters the intake system allowing for the proper amount of fuel to be...

Q: Q: How do I turn on the heated mirrors?

The heated mirrors feature allows your mirrors to be heated up, which can dispel of moisture or frost, and increase your visibility. To turn on the heated mirrors, press the rear window defogger button on your center console.

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
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...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...