Skip the auto shop - Our mechanics make house calls

Q: Air conditioner blows colder at idle and heater blows slightly warm.

asked by on

ac blows cool when driving but cold at idle and the heater blows slightly warm even after driving several miles. The engine coolant is full , one heater core hose is hot and the other is considerably warm, engine temp is normal . I have heard a loud pop inside the cab recently like the the blend door slaming shut a couple of times before this problem . Can u tell me how and what to check ? 2002 f150

My car has 100000 miles.
My car has an automatic transmission.

Hi there. A blend door could be stuck and causing the outside air to enter the cabin compartment. Check the blend doors to see if they are sealing shut. If they are not sealing shut, then check the actuator and make sure that its working. Most actuators can be vacuum or electronic. Replace the actuators if they are not working properly. If you need further assistance with your heating and air conditioning, then seek out a professional, such as one from Your Mechanic, to help you.

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!
  1. Home
  2. Questions
  3. Air conditioner blows colder at idle and heater blows slightly warm.

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 service light says service temp. What do I need to look for?

Hi there. A low coolant level can illuminate the service light and create the heating and AC problem you have described. Check the coolant level while the engine is cold and top it off as necessary. Also, look around the...

Q: fan blower slow to turn on

Thanks for writing in about your 2012 Suzuki SX4. The blower motor must of got water in it and has caused it to have a short internally. If you locate the blower and have it turned on but it doesn't...

Q: the security system was activated and now only runs up to 50mps.

There are a couple of possibilities here. Check fuel pressure while driving the car. If fuel pressure is below spec, or drops the closer you get to 50 mph, then your fuel pump may be worn out, fuel pump relay...

Related articles

What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
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.