Question about 1999 Pontiac Montana

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I have a vapor lock in the cooling system that I can't fix. I changed the thermistat because I was getting very little heat, that worked for a while, then April of 2010 I couldn't get any heat from the front or rear heater, it was like that all summer. The cooling system worked fine just no heat. In August I pulled the dash apart to check the controls and ducts and they worked fine. I wormed the engine to operating temperature and the heater core was cold, so I back flushed the system, and still no heat. I opened the bleeders to get the air out, I would drive a mile out and back and bleed the system again, and I did this 10 or 12 times and finally the heaters worked again. That lasted about a month and the temperature gauge fluctuated and the heaters quit working again. I bled the system and the heaters work for about a month and I had to bleed it again, now that the weather turned cold the heaters work intermitently and I have to bleed the system almost daily. What can I do to fix the problem.

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Alright here goes the van probably has the 3.1 or the 3.4 engine the engine is fited with a bleeder valve that when you change your coolant or change a thermostat you will have to bleed all the xtra air that is in the lines if you dont the antifreeze will not circulate and causes no heat and could also cause your engine to overheat tearing up your engine. make sure you find the bleeders and get all the air out and you should have heat. hope this helped

Posted on Jan 03, 2011


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