gray heat valve vacuum line

[flathead40]

On a 2006 XLT where under the dash does the gray vacuum line that goes to the heater control valve origanate from under the dash? On the 06, 4.0 when you turn the heat down or the a/c is called for vacuum goes to the valve to close it. I bought a new valve thinking that was the fix, and tested it before installing it by hooking too the gray vac line and it stayed open on cooling just like the orig valve. The a/c and blend doors all work fine. Is there a some sort of diverter behind the control panel in the center dash? Asking before I take the dash apart. Thanks for any help!

 

[flathead40]

I have vacuum under the dash but no vacuum going back to the heat valve to hold it closed when the control is set to cooling or a/c. The gray line to the heat valve go's behind the ductwork behind the center dash and must attach to a juntion then change color before going to the heat a/c control panel. It is only acessable by removeing the majority of the dash and plastic duct work. Anyone know which line on the control panel sends vacuum to the heat valve?

 

[Trainmaster]

I'm wrestling with the same thing on my 2010. I have the Automatic Climate Control. The vacuum lines plug into a Vacuum Solenoid Control Module that is next to the console on the passenger side just under the glove box. This switches vacuum based on current from the Climate Control head in the dash.

I believe the cars with Manual Heat and A/C have a vacuum hose connector that plugs directly into the heater controls.

The black hose is your vacuum source that comes from the back of the motor with an in-line check valve and follows the grey heater valve tube through the firewall.

The Heat Control Valve is supposed to get vacuum, which closes it, only when the controller is set to OFF. Temperature is controlled by blend door dampeners in the heater plenum using electric actuators to direct air flow over the heater core and a/c coil. The heater hose valve remains open when the cooling or heating is on, so you can temper the air. I checked my Solenoid Module and it works fine, but the controller never seems to command the valve closed.

To answer your question, the gray hose is vacuum to the Heater Control Valve that's on the heater hose and the black hose is the vacuum source from the intake manifold.

 

[flathead40]

I'm wrestling with the same thing on my 2010. I have the Automatic Climate Control. The vacuum lines plug into a Vacuum Solenoid Control Module that is next to the console on the passenger side just under the glove box. This switches vacuum based on current from the Climate Control head in the dash.

I believe the cars with Manual Heat and A/C have a vacuum hose connector that plugs directly into the heater controls.

The black hose is your vacuum source that comes from the back of the motor with an in-line check valve and follows the grey heater valve tube through the firewall.

The Heat Control Valve is supposed to get vacuum, which closes it, only when the controller is set to OFF. Temperature is controlled by blend door dampeners in the heater plenum using electric actuators to direct air flow over the heater core and a/c coil. The heater hose valve remains open when the cooling or heating is on, so you can temper the air. I checked my Solenoid Module and it works fine, but the controller never seems to command the valve closed.

To answer your question, the gray hose is vacuum to the Heater Control Valve that's on the heater hose and the black hose is the vacuum source from the intake manifold.

Yes I know about the gray and black lines. My problem is vacuum never go's back to the heat control valve, something under the dash isthe issue. I have the manual controls, which has a vacuum reservoir behind the glove box.

 

[flathead40]

The heater control valve also closes on "max a/c" as well as off.

 

[Trainmaster]

The heater control valve also closes on "max a/c" as well as off.

Even on the Automatic Temperature Control cars?

 

[flathead40]

Even on the Automatic Temperature Control cars?

 

[Trainmaster]

The heater control valve also closes on "max a/c" as well as off.

Even on the Automatic Temperature Control cars?

Mine doesn't do that. It seems to never close. The solenoids test good, so I guess I'm changing the controller.

 

[flathead40]

I changed my controller made no differance. Like I said the gray line goes behind the plastic ductwork and does not come back out. It would be a majour job to take apart to find whats going on.

 

[Trainmaster]

Well the two of us are in the same boat. Does anyone's valve close on "OFF" or "MAX A/C"?