wierd heater
need help have a 99 sport runs just below 200 degress dosn't overheat. the problem is i will turn the heat on while idleing and get no heat but when i start driving it will come on, then when i stop to idle it goes back to cold air. the fan never changes speed I know a little about mec. and understand the coolant is what heats up the truck but what would make it go to cold air at idle and back to normal when driving:brickwall: ( thats in gear or not)
thanks for any help |
Low vacuum to you're heater controls maybe.
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You may have a vacuum line that is collapsing. Your engine produces higher vacuum at idle and it lowers as you step on the throttle. A collapst vac line will be noticeably flat during idle. Good luck.
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.....and heater core could be partially plugged as well as water pump impeller could be half gone, or both.
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Does anyone know were i can find a vacum diagram
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I thought the "blend door" (sends more/less heated air to the cabin) was cable operated, no? Vacuum controls which vents air (hot or cold) blows from.:dunno:
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Originally Posted by djb383
(Post 2733326)
.....and heater core could be partially plugged as well as water pump impeller could be half gone, or both.
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i will check out both is there a way to check the heater core without pulling it out
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Originally Posted by mrrecon4
(Post 2733491)
i will check out both is there a way to check the heater core without pulling it out
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Perhaps due to Low vacuum to you're warmer controls..
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Have you checked your coolant level? That is a classic symptom of low coolant level.
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looks like its fixed, flush core both ways until it was clear some crap out not to much, also low on antifreeze. not sure about water pump mainly wondering where antifreeze went (wheres it leaking) thanks for all the help and i too have a 11/16 hose on the inlet
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Originally Posted by djb383
(Post 2733326)
.....and heater core could be partially plugged as well as water pump impeller could be half gone, or both.
His impeller probably looks like a Chinese Throwing Star. LOL Edit: OOPs, looks like he fixed it. That will teach me to hit the refresh button before posting. |
Originally Posted by djb383
(Post 2733387)
I thought the "blend door" (sends more/less heated air to the cabin) was cable operated, no? Vacuum controls which vents air (hot or cold) blows from.:dunno:
Vents are vacuum operated . |
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