Skip the auto shop - Our mechanics make house calls

Q: How Long Will the AC Run if My Engine Is Off?

asked by on

How long will my AC run if my engine is off?

The ability your car has to make cold air for your comfort stops when the engine does. The heart of the A/C system is the A/C compressor, whose cycling clutch is driven by a belt connected to your engine’s pulley. If the engine is not turning, the A/C compressor won’t be turning either.

After shutting the engine off, when the A/C has been on, you will notice cool air still coming from the vents if the blower fan remains on. However, you’ll also notice that the temperature of that air soon begins to rise since the refrigeration portion of the system (compressor) has been shut off. An exception to this would be on some hybrid vehicles that have electric motors turning their compressors enabling the A/C to still operate even when the gasoline engine is in idle-stop mode.

If you run into any issue with this system, there are ways to diagnose the automotive air conditioning system by yourself. However, if you feel overwhelmed, reach out to a certified mechanic who will be able to diagnose and fix your A/C.

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: My car will not idle at a stop light.

This may be a sign of a failing throttle position sensor or a failing or dirty idle air control valve. The throttle position sensor (TPS) is a sensor used to monitor the throttle position of the throttle plate inside the...

Q: How do I customize the Remote Start Auto Heat Seat settings?

The Remote Start Auto Heat Seats setting allows you to choose whether or not the heated seats turn on when using the remote start feature on cold days. Adjusting the settings takes only a few steps: 1. Turn on the...

Q: My car rough idles and stalls, but no check engine light.

This issue is normally caused by low fuel pressure or a faulty injector, but since you have just replaced the fuel pump, this may also be a sign of a failing idle air control (IAC) valve. This is a unit...

Related articles

How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.