Skip the auto shop - Our mechanics make house calls

Q: The front heater works only at high RPMs and the back only blows cold air

asked by on

My vehicle has an issue with heating. Actually, there are two separate heaters that are controlled separately. One is in the front and the other at the back. The back one isn't toatally unresponsive, but it doesn't heat just blows cold air. Whereas, the front works when the RPM is about 2500. Please give me some suggestions. Thanks.

A: There are two distinct possibilities: there...

There are two distinct possibilities: there is either no warm coolant to the rear heater core or a blend air flap is permanently in the cool air position. With no warm coolant to the heater core there will be no way to get the air in the hot air circuit. If the blend door is not moving in the rear climate control box, then air is only fed through the cool air side and not the warm air side.

A temperature check of the rear heater core will determine if coolant is being circulated through the core, and an inspection of the blend air flap and control on the rear climate box will determine if air being drawn through the warm air circuit. You may want to enlist the help of a mechanic, such as one from YourMechanic, who can diagnose and correct the rear heater circuit.

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: ABS light comes on when pushing brake.

The problem you are having is not very common. However, based on your description it could be only a couple things. First off, the ABS Light is controlled by the ABS control module. The module gets inputs from various sensors...

Q: My truck is bucking at different speeds but it smooths out during acceleration.

Hi there. Check the contacts to the engine oil temperature sensor. See if the contacts are loose and if they are falling off. Also, check the wiring to the sensor and see if its over a spark plug wire. Its...

Q: Car won't start, is it my ECU?

Hi, thanks for writing in. While it could be the ECU, it could also be a great many other things. It is most likely not any one component but is probably a combination of faults. Many years ago you could...

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
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...
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...