No Heat

[chertaichi]

The heater in my truck hasn't worked for a couple of years. At first when I turned it on I got heat sometimes and no heat at other times. I don't think it's the heater core as I didn't get fluid inside the vehicle. The blower (fan?) is working and the A/C works okay. The temp gauge is right in the center so don't think it's the thermostat. My friend said it might be a fuse or doors that open to allow the heat in.
Any thoughts about this? I know it's summer but I want to get it fixed before the cold weather.
Thanks for any help.

 

[Rifleman]

Have you checked the fuses?

 

[dangerranger83]

Well from personal experiance Ive changed out heater cores because of them being clogged with corrosion, crap, etc and that would keep fluid from passing through it. And on newer veihicles that heater cores are made of aluminum and they can corrode fast from running to much tapp water in the system and to little antifreeze.

 

[v8318cid]

I agree with Dangerranger83 in that your core is probably plugged. You should also check the operation of the blend door though. The easiest way to test this is to set your fan on high and turn the temperature knob from COOL to WARM and listen to the sound. If there is a slight change in the pitch or fan noise, your blend door is probably working correctly. Keep in mind that it probably won't be as obvious as changing from MAX A/C and NORM (Panel on older models). You can also check the inlet hoses on the heater core from inside the engine bay. If the core is stopped up, one hose will have a notable difference in temperature from the other. As to which is inlet and which is outlet, I cannot tell you. I don't think it matters other than how the hoses were hooked up from the factory.