Heater not working properly. 1990

[spahrster]

Hey all,

I have read several posts about other truck heating issues.

The blower is blowing air, but the air is not hot. I checked the valve just ahead of the firewall and it open and closes normal.

I removed the two hose connections going to the heater core and used a garden hose to flush it out. The antifreeze that came out looked ok with no clogs or major discoloration. I did notice that when I removed the hoses on top, there was very little antifreeze or water that came out. Its like maybe there is not enough pressure to get it to the heater core part.

My reservoir for the antifreeze was bone dry and I filled it back up again, but after driving the truck for 20 minutes, the level is still the same and the air still doesn

 

[the_dingman]

First off, what does you're temp gauge do?

If it stays at cold, you could have a defective thermostat, which may be stuck open causing your engine to never warm up and give heat. (this was my problem on my older T4R, I fixed the problem with a $15 part, granted my head gasket blew the next week).

If the gauge is working, it could be an issue with a clogged hose or a bad cable in the controls causing the heater core to never warm up.

You mentioned that the antifreeze was empty, and that would be an indication of a very big problem and a possible cause of the problem.

 

[spahrster]

same

Hello the_dingman,

The temp gage does move. It never really gets over a quarter of the way, but appears to be working.

I bought the truck used and it looks like the radiator is brand new. Maybe I shoud start troubleshooting the intire coolent system delivery. If it was replaced, there must have been an issue at some point.

I do have the rear heat vents. Maybe I should check to see if it blokes hot. I think those hoses bypass the heat valves and also the heater core.

hmmmmm,

Michael.

 

[the_dingman]

I would check your thermostat, it sounds like your engine is never heating up all the way.

 

[spahrster]

The heat is fixed!!

Yup, you guys were right. It was the thermostat. Actually, once I took the housing apart, there was no thermostat there at all! Totally empty. Go figure. After a15 dollar replacement, it heated up real quick and ran like a charm. Even the rear blower is cranking out hot.

One question, I didn

 

[drmorbius]

Re: The heat is fixed!!

One question, I didn

 

[the_dingman]

Water will work, but as mentioned, antifreeze will keep your system from rusting on the inside.