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Heater won't warm up

Join Date: Dec 2007
Posts: 32

December 17th, 2007, 4:43 PM   #1  
CF Junior Member
Heater won't warm up

I have a '94 Chevy Silverado w/tow package & plow on it. I don't know if the temp guage works but it's constantly under 100 degrees and doesn't blow any hot air. I did change the thermostat and that didn't help. I've had the truck for 2 years now. It was like this last year and I dealt with it, but I'm freezin my a** off & I need it fixed. Anybody know what could be the problem? Or where to start looking?

Join Date: Aug 2006
Posts: 2,424

December 17th, 2007, 5:14 PM   #2  
RE: Heater won't warm up

Use a kitchen thermometer and check to see how hot the coolant gets after the truck has idled for at least 20 minutes with the radiator cap off, if it gets up over 150F then your problem is most likely a faulty engine temp sender along with a bad heater water flow valve.
I would also make sure that the heater hoses are routed correctly and someone didn't bypass the heater core or the valves.

If that coolant doesn't get very hot then I would take another look at the thermostat and make sure that you use a correct OEM 195F and that it is installed correctly.

Also make sure that your fan clutch is not stuck engaged, if it remains on constatly it will super-cool the anti-freeze, make sure the fan spins freely by hand after the truck has been run for at least 5 minutes.

Join Date: Oct 2007
Posts: 3

December 18th, 2007, 10:20 AM   #3  
RE: Heater won't warm up

i would go with the kitchen thermometer to to see how hot it was .....and then u can fix the problem

Join Date: Dec 2007
Posts: 32

December 19th, 2007, 4:51 PM   #4  
CF Junior Member
RE: Heater won't warm up

I had it running for over 1/2 hr while plowing & felt the hoses-they were cold. I took off the radiator cap and the water was not hot. I could put my finger in it. I followed the heater hoses from the heater core &one runs directly into the radiator & the other one runs into the back of the engine block. On my other Chevys I've owned usually one comes off the water pump & goes in, and the other one comes somewhere off the block. Could this be the problem? Could I correct it by getting a different water pump with an opening for the heater hose?
STILL tired of freezin my a** off!
Thanks for the help!!

Join Date: Dec 2006
Posts: 6

December 28th, 2007, 6:40 PM   #5  
RE: Heater won't warm up

I have exactly the same problem and would like to know if you already fixed the problem.
Yeah, exactly the heater hoses run from back of the engine block to the h core and the returning goes to the upper side of the radiator.
I just loose the returning hose and with the engine running checked if was water coming out, but the hose was all the time empty and the hose that is coming from the engine block feels so soft when engine is running, then looks that nothing water is coming from the engine block. I have been trying to remove that hose but is very complicated since is in the upper back of the engine with minor space to work on it. Same time i have been looking for a heater valve but doesn't seems that exist that valve in the system.
Any ideas to remove the back hose where is installed the valve?

My car is a Silverado '94 ext cab with 5.7


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