Q: Heat only works when accelerating

asked by on

The heat only works when accelerating had a coolant flush thinking that would help it did not . They did bleed it the right way twice the heat works for about 20 mins then goes back to only when giving gas . I changed out the thermostat for a different reason but the problem was still accruing also had the radiatior changed then had it bleed about 6 months ago now it's cold had it bleed twice and still having the same issue

My car has 129000 miles.
My car has an automatic transmission.

Hello. I suspect the heater control valve is the culprit here. Most likely only opening partially. By only being partially open, it allows more hot water to circulate when the engine load and RPM are higher, as when you accelerate, but not enough otherwise. Another possibility it that the heater control mechanism (most are electric these days) is not signaling the air blend doors. The circulating air controls which "mix" cool and hot air before it comes out of the vents - resulting in too little hot air coming out of the heater ducts. If you would like to have this taken care of, I recommend having a certified professional from YourMechanic come to your car’s location to inspect the heater system and proceed with any needed repairs.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Heat only works when accelerating

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: No heat in car and engine light on for overheating

Hi There, Your heating issue may be due to a faulty heater blower motor or potentially a bad heater core. As you may know, the heater core is a small radiator like unit that circulates the hot coolant from the...

Q: Car not starting because of alarm system

There is a few issues related to the alarm system that could be causing the problem you are having and more information would be needed to diagnose the problem for you. The remote may be having an issue with the...

Q: Q: Water leak

If the sunroof is much like a window. It has a switch, motor and a regulator/track assembly that moves it back and forth. If the switch or motor fail it will not operate. These failures are not common but they...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
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.
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.