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!
  • Home
  • Questions
  • 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: How to remove dashboard to b able replace the heater core?

Hello. Replacing the heater core is an extensive job. You can subscribe to AllData DIY and purchase a short subscription to factory information and repair procedures. It costs about $27 for one year of unlimited data. I recommend you have...

Q: Problems with the Driver's Side Blend Door Actuator

Turning the actuator to full cold will not find the problem since the actuator internal sensor is bad and cannot control the motor and then will default all the way to heat. You can replace the actuator and run the...

Q: Heater blows cold when temp gauge is halfway. both heater core hoses are hot.

If both heater hoses are hot then the core is getting hot coolant flowing through it. You should check the temperature blend door actuator behind the glove box on heater case to see if it is operating the temperature blend...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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...
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.