Heater not working, thermostat stuck closed?? - Diesel Forum - TheDieselStop.com
1999-2007 General Questions General questions related to 1999-2007 Super Duty trucks. If it doesn't fit the other categories, post it here. Gas engine discussion that pertains to all models is allowed. Specific gas engine questions should use the Gas Engines forum.

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post #1 of 4 (permalink) Old 04-09-2010, 12:29 AM Thread Starter
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Heater not working, thermostat stuck closed??

Recently it got cooler down here in TX and when i turned on my heater up all the way with full blast, nothing but cool air was blowing out. Yes, the engine temperature was in operating range between C and H. Im thinking thats the result from my thermostat possibly being stuck closed for whatever reason. Luckily, its hot during the day so i run the AC most of the time but just wanted to know due to my next problem; for some reason, the trans. temp. needle stays near the "C" range. I drive, say 20 miles with the engine hot but the needle only goes up 1/4 of the way and stays there instead of normally being in the center of C and H like usual. The two issues seem connected since it sounds like a problem that affects proper cooling and heating of the climate control and transmission. Anybody have suggestions???
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post #2 of 4 (permalink) Old 04-09-2010, 12:37 AM
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similiar thread - I'll bet this is your problem , not the cooling system.
AC/Heat control problem, not the defrost though

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post #3 of 4 (permalink) Old 04-09-2010, 11:30 AM
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Originally Posted by viper_09 View Post
Im thinking thats the result from my thermostat possibly being stuck closed for whatever reason.
Is your upper radiator hose hot? If it's hot, the thermostat is not stuck closed.

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post #4 of 4 (permalink) Old 04-09-2010, 08:23 PM
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A thermostat stuck closed would make the coolant hotter. Hotter coolant would make the heater warmer not cooler.

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