Heater Control Valve

[Lefty2053]

In a previous post I had found a loose Vacuum line. I was told it was for the heater Control Valve. I didn't have a valve on my Explorer. I just bought one and put it on. It only closes the valve when I put the knob on Max A/c, If I put it on A/c only it doesn't close. If you look at my other post. http://www.explorerforum.com/forums/showthread.php?t=339959&highlight=hose

You can see they had put in 2 Valves on each of the lines going in and out of the Heater Core. Before I bought the Valve I just closed off the in side and was able to get my A/C working.

What would cause it not to close when on A/C with the control valve attached?

 

[budwich]

That's how it is supposed to work. Only max AC shuts the water valve.

 

[Maniak]

I think its working correctly. With the valve closed it stops hot water from going into the ac/heater box which can help the ac get colder.

They didn't even put that valve in until 1995. Without that valve (and the lines connected to the heater core) all that happens is heater core has hot water in it.

If everything is working correctly the ac but if there is any blend door leakage the ac won't get as cold as it possibly could.

I've never watched the valve work on a 2nd gen but all the other vehicles I've seen that have it only close the valve on max ac.

~Mark

 

[koda2000]

That's how it is supposed to work. Only max AC shuts the water valve.

it's the blend door that does most of the work separating the heater core and a/c evaporator w/in the plenum, except when in MAX AC mode.

 

[Lefty2053]

When I had the t-fitting on there I could shut down the water flow and get the A/c to work. So I thought that the Water flow needs turned off by the Heater Control valve when I turned it to a/c. With the Water flow open I get constant heat in the cabin without the Heater control valve and with it when I turn off the heat the valve closes. SO I guess I need to use the Heater Control valve in the Winter and the other valve in the summer so I can get A/C.

Blend door works fine when I turn on Max A/C. But not when I turn on just A/c.

Auto Parts guy said he thinks I have a knob leak and when I put it in A/c mode the vacuum leaks out the knob.