Q: Q: Heat

asked by on

Replaced radiator and thermostat due to over heating.fixed that problem but now the heat blows luke warm.used 50/50 antifreeze when filling it

My car has 165000 miles.
My car has an automatic transmission.

The most common reason for this after a repair is an air bubble in the system. Most of the time, if you completely warm the car, which means you have confirmed the thermostat is open by feeling the upper radiator hose it hot to the touch. If it is and the car isn’t overheating, take it for a test drive on the highway. Air bubbles can create overheating conditions, so do go to far. You only need to go about 45 mph for a few minutes. Once you get home, let the car cool for about an hour. Remove the radiator cap and see if coolant is all the way to the top of the radiator fill. If not, top it off and take a drive again.

This will often take a few tries to get the system to completely bleed. Sometimes I have had to run motors multiple times to get them to bleed the air bubbles from the system. The best test for a completely full cooling system is to check it first thing in the morning. This is when the cooling system will contract the most making room for more coolant.

If you determine the cooling system is full, but you still have luke warm air coming from the vents, the next thing to do is feel the heater hoses coming from the heater core at the fire wall. One should be really hot and the other should be cooler, but not significantly colder. If it is, you have a clogged heater. The easiest, thing to do at this point is flush the heater core. There are multiple ways to do this. Whatever way you choose, be sure to flush it both directions. If flushing doesn’t work, you will need to replace the heater core.

My information system doesn’t show there to be a heater control valve on your car, but I would still keep my eyes out for one. If it has one, make sure the valve is opening and closing.

I recommend the following inspection to help you should you need further assistance; Heater is not working replacement. Be sure to send the technician a note explaining your symptoms so he or she can come prepared.

Good luck!

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

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 07 explorer 4.0L hesitates and hums when I'm on the gas pedal, but I can accelerate smoothly and quietly using cruise control.

The noise and loss of power may or may not be related. The vibration might be related to the poor operation but other causes such as faults in motor mounts can cause vibration not to mention a faulty harmonic balancer....

Q: Overheating, drop in oil pressure when coming to a stop

I would start by checking the thermostat. If this is not working correctly, the car will quickly overheat. Driving may temporarily keep the temperature down due to wind circulation, however once you are stopped this goes away, especially if the...

Q: When doing a radiator flush - do you need to replace the thermostat or any other components of the cooling system

Doing a radiator flush does not require any other component to be replaced. However, if the system has a lot of debris and scale in it, the thermostat may need to be replaced if it gets clogged or corroded. The...

Related articles

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...
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...
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.