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Hi all and TIA for any help,
I just bought an 86 full size bronco XLT with a 351 W HO. My problem is the heater just quit working. It worked when I first got it. It appears there are vacuum operated valve(s) that control the water flow to the heater and I suspect this is where the problem is. How do these valves work? How can I test it/them? Where can I buy them and how much? The books I have do not show how the temperature control lever is tied in to the control. Any tricks or info is appreciated.
Tom
After your engine is warm, turn the heater on and then check the temp of the both heater hoses under the hood. If both are hot, then the valve is ok and your problem is probably in the vacuum system. If only one side is hot, then the valve is not opening and you can go from there.
Hey thanks for the reply.
After I got into it I found that what I thought were vacuum valves are really thermally activated vacuum switches/valves. They had nothing to do with the heater circuit. On this Bronco there is no heater valve. The temperature control opens a by pass damper in the air flow around the heater core. The heating water flows thru the heater all the time. Ultimately I found the problem to be a 100% plugged heater core. I tried back flushing with no success. So a quick trip to Autozone and $20 and everything is cool, er warm.
Thanks again
Tom