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**davischevy** · 05-30-2014, 04:13 PM

On the right inner fender, there is a valve in the heater hose with a little vacuum line running to it. When you turn on the AC the vacuum from the control panel closes the flow of hot water.

I would first pull vacuum on the valve. If it holds, you are losing vacuum somewhere between the control panel and the valve. You will have to pull the glove box, and check the vacuum line behind it.

05-30-2014, 04:13 PM	#5
davischevy Senior Member Join Date: Sep 2008 Location: Harrison, Arkansas Posts: 9,881	Re: heater out of wack On the right inner fender, there is a valve in the heater hose with a little vacuum line running to it. When you turn on the AC the vacuum from the control panel closes the flow of hot water. I would first pull vacuum on the valve. If it holds, you are losing vacuum somewhere between the control panel and the valve. You will have to pull the glove box, and check the vacuum line behind it. __________________ other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless.