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Old 03-05-2007, 09:38 AM
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Re: 99 blazer heating problems

Quote:
Originally Posted by banditace
I know this is a dumb question but I am tired of waiting on my husband to fix this. how do I check the good vacuum from engine to heater controls and check for the heater core leakage?

thanks becky
To check for good vacuum you will need a vacuum gauge and find the main vacuum line that supplies vacuum to the heater controls.
It should have 18-20 lbs of vacuum on it from engine.
Some place between the engine and heater controls there is a check valve and most of the time a small reserve vacuum tank.
The reserve tank holds a vacuum supply check valve keeps vacuum on the heater control even when the engine is under load or no vacuum.
Look and listen for vacuum leaks and bad vacuum hoses/lines.

On heater core leakage look for coolant on the bottom of heater core housing and for windshield fog up and also a sweet smell from heater is a good indication of a leak.
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