Q: No heat when ideling or driving slow.

asked by on

I changed water pump, thermostats ( mechanic said there was 2) , heating coil , bled air with vacuum service. No leak in head gasket. Top hose on radiator is hot and bottom hose is ice cold. The engine is not over heating.

My car has 90000 miles.
My car has an automatic transmission.

The lack of heat being generated by your system may indicate a clogged heater core. The [heater core]((https://www.yourmechanic.com/services/heater-is-not-working-inspection) is a small radiator like unit that circulates the hot coolant from the engine through the heater core which then uses this warm coolant to heat the inside of the car with the help of the blower motor that blows the warm air through the vents inside the car. The other possibility is that the thermostat may not be allowing the engine to reach a normal operating temperature and since the engine’s warm coolant is the essential source of the heater core supplying heat to the inside of the vehicle, this can impact the warmth of the heat inside the vehicle. I would suggest having an expert from YourMechanic come to your location to diagnose your heating system.

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. No heat when ideling or driving slow.

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: Whining from tensioner or AC compressor

Hi there, if the problem only occurs when the engine is cold then it is most likely the tensioner or something to do with the timing chain. The A/C compressor would create the noise when the A/C is turned on,...

Q: My car is not starting when the MAF sensor is plugged in - 1991 Nissan Serena

This may be a sign of a dirty or failing mass air flow sensor. The mass air flow sensor is a unit in the intake system that monitors air intake as it is mixed with fuel prior to being injected...

Q: Heater air is blowing out cold on the passenger side of the vehicle when the heater is on, warm on driver side 2011 Dodge Journey

Hello - your "no heat" problem sounds like an ambient air temperature sensor on the passenger side with problems, or a malfunctioning air blend door inside the heater air box. I would recommend a heater inspection by a mobile, professional...

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...
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...