weird heater
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Freshman User
Joined: Jan 2009
Posts: 29
Likes: 0
weird heater
i have a 99 f150 ext cab 5.4 triton
after my engine is warmed up the heater blows cold air then it gets warm then cold then hot jus at random
sometimes theres np wit it then its doesnt even blow warm air
its weird as hell any hints on what it might be?
after my engine is warmed up the heater blows cold air then it gets warm then cold then hot jus at random
sometimes theres np wit it then its doesnt even blow warm air
its weird as hell any hints on what it might be?
Hotshot
Joined: Jul 2005
Posts: 11,932
Likes: 181
feel the heater hoses and top radiator hose. also what is the temp gauge saying? like KR said, when the temp comes and goes, that normally means the radiator is a 1/2 - 1 gallon low. make sure you dont have an air pocket. driving around , start, stop , will normally get any air out.
Hotshot
Joined: Jul 2005
Posts: 11,932
Likes: 181
well if the heater core is full of water, then either you dont have any water flow thru the core.......... or the blend door is broken and your mixing cold air all the time??????? feel the heater hose, if they are hot, then the blend door is broken and your mixing too much cold air with the hot.
Hotshot
Joined: Jul 2005
Posts: 11,932
Likes: 181
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New User
Joined: Nov 2008
Posts: 6
Likes: 0
From: manchester
this sounds like my truck is doing exept mine it will loose the heat and by the time you pull over the temp gauge will spike to hot and if you shut it off it will pump out coolant then start it back up and it is fine the rest of the day i put head gasket in a bottle in it it worked great for about 3 months and now its back and nothing will help it. i figered it has a cracked head. dont know if that would be your problem or not when you lose heat do you build psi in your radiator hose at all.
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Junior User
Joined: Oct 2006
Posts: 84
Likes: 0
From: New Orleans East
i had a similar problem once, and i know this sounds somewhat foolish, but the problem was the plastic temp control **** on the dash... it had what appeared to be a hairline crack where the plastic **** attaches itself. The actual metal **** that it is supposed to turn wouldn't because this tiny crack was causing the plastic **** to slip. I suggest taking out the **** and thoroughly inspecting it, its pretty simple. Or, if you can't see any cracks, try turning the metal **** with pliers or somethin and see if the a/c and heat work properly then.
however, i have also had to replace the blend door motor (went bad about a year or so later, not related) and have had to replace the heater core, so it could be any of those problems.. except usually when the heater core is busted, you get that delightful smell of radiator fluid
however, i have also had to replace the blend door motor (went bad about a year or so later, not related) and have had to replace the heater core, so it could be any of those problems.. except usually when the heater core is busted, you get that delightful smell of radiator fluid
Tuned
Joined: Apr 2001
Posts: 467
Likes: 25
From: Central Callifornia
vacuum leak...maybe?
I think that you might have a control/vacuum problem. Are the problems speed/rpm related? Our company had Econoline chassis' that would change from dash(AC) to defrost at 35-40mph cruising at 1yr old. Found collapsed/cracked vacuum resevoirs. jus another avenue to check.