Heater has only been blowing cold air. Had radiator flush and fill last week. Still only blowing cold air. Any thoughts ??? Need a new thermostat, or more serious ?? How do I access thermostat if that is the problem ???? Thanks... I am cold and waiting..........
More information on your truck is needed like the year of the truck, the engine size, if you have A/C or not. These are important.
The most common problem for no heat is the thermostat. If you have a temperature gauge on the dash you can check the temperature of the engine this way. If the gauge works the temperature should be about half way or read about 200 degrees.
The thermostat is usually located in the engine just under the upper radiator hose. Knowing the proper engine size I can give you the exact location.
You can also take the radiator cap off when the engine is cold and run the engine till it warms up. With a thermometer in the neck of the radiator you can check the temperature this way. The thermometer must be able to read up to at least 220 degrees.
There other problems that can happen like the heater door in the heater box is stuck closed or malfunctioning. Depending on the year it can be electronically controlled or the door is moved by a manual cable.
If there is a water control valve inline with the heater hoses, this could be stuck closed causing a no heat condition.
Get back to me with more information and we can go on from there.
Try these suggestions first. Let me know how you make out.
Thanks so much for the tips. I have a 2000 GMC Sierra 2500 with a 5.3 L engine. The temp gauge does reach the halfway point.... I will try taking off the radiator cap and warming up the engine... I really appreciate the help. I am a student and having a big repair bill now is daunting. I will let you know how this plays out. Thanks again