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Post by daylilydude on Apr 13, 2012 4:11:41 GMT -5
Just noticed this happening on my truck, when idling the temp gauge rises and I get heated air when I turn on the heater, but when I start driving it the temp gauge drops and starts blowing cold air... and ideas?
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Deleted
Posts: 0
Joined: January 1970
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Post by Deleted on Apr 13, 2012 6:48:09 GMT -5
Is it overloaded? All I got is the obvious checks to do....if that doesn't fix it then a trip to the truck vet is the next step. good luck.
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izzy
Pro Member
Posts: 347
Joined: July 2011
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Post by izzy on Apr 13, 2012 14:44:35 GMT -5
I'm not sure we're talking about the same thing - but it sound a lot like the situation with my 2002 S-10. Only difference is that you are turning on the heater; I was turning on the a/c. Whenever I idled - at a stop light, the bank, whatever, the a/c blew superheated air. Only when the truck was moving, then the a/c blew cold again. Sounds a lot like what you have going on. I bought the truck new from the dealership, and never got any satisfaction from them - they said they were made like that to protect the a/c - something like that - it's been more than 10 yrs. since I first bought it. They said nothing was wrong with it. The most I could do was 1. make sure the temp dial for the a/c was in the coldest position, and 2. turn off the a/c if idling for more than a few seconds and open the windows until the light changed. It was cooler that way. In ten years, no mechanic could figure out how to solve the problem (actually, it seemed like I was one of those customers they couldn't please). My new chevy truck does not have that problem.
I hope you have a problem that's an easier fix than mine.
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peapicker
Junior Member
Posts: 73
Joined: April 2011
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Post by peapicker on Apr 13, 2012 19:15:21 GMT -5
The Dudes problem could be the thermostat or it could be out of timing Izzy I have no idea about your problem,maybe AC filter
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reubent
Pro Member
Posts: 389
Joined: May 2011
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Post by reubent on May 21, 2012 23:30:02 GMT -5
It has to do with the engine speed, and the thermostat. When the engine is running slow the water pump produces very little pressure, the flow through the heater flows easier than through the thermostat. (heater flow bypasses the thermostat) So hot water is going through the heater but not getting pushed up against the thermostat quite as much. When the engine speeds up it pushes hot water against the thermostat stronger, it opens, and cool water runs in from the bottom of the radiator, cooling the heater. However the unevenness is not usual. It may be a sticky thermostat popping open suddenly instead of the gradual opening it should do. Or it could just be the idiosyncratic nature of the particular vehicle. My dad's car has a funny thing where after starting cold the guage temp will go up to mid range with no heat from the heater, then the the thermostat would pop open, guage temp would drop, and then slowly build up again as heat started coming from the heater. Acting like the heater flow was going through the thermostat (never seen one made that way) combined with a sticky thermostat that would hang closed until the temp went up a good bit.
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