Q: Heat

asked by on October 14, 2016

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!

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