Ford Aerostar
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How do you find a heater control valve on a 91 Ford Aerostar because you think it is stuck shut?

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2015-07-15 18:59:53
2015-07-15 18:59:53

It s/b near or behind the alternator. Follow the hoses. Also, check the vacuum system that runs the valve.

'94 Heater door not engagingI am not sure how old this post is, however, I have recently discovered the same experience with my '94 aerostar. The door, is located behind a vacuum assist diaphragm on the engine cover underside, behind the alternator.

It is actuated, from what I can tell, by the action of yet another vac assist dia., located at the heater core hose connection point.

Pull off the small tube at this diaphram, and hold finger over dia. fitting. Press down on linkage of dia. If dia. is good, there will be no release of vacuum. If there is releas to original psoition, dia. is faulty and should be replaced. The same procedure can be done on the door dia. as well behind the alternator.

If all check out o/k, check your vacuum lines from your engine out, perhaps even a carbon build up on the tube.

NEW ADDITION: The "hold your finger on it" test is not always reliable. There is a small grove cut into the vacumn attach point that may allow air to escape during this test. Don't buy the new one (around $20.00 aftermarket, $80.00 dealer) until removing the old and properly blocking the vacumn port, say with plumbers putty or proper size vacumn plug. Push the rod down first, then close off to do leak down test. If the rod slowly "rises", replace the unit, being sure to install with proper orientation, I suggest lightly coating the heater hose attachment with lubricant (vasoline) to ease the installment. By removing the bugger, you can "see inside" the water port and tell if it is gunked up or has a build up of heavy metal deposits preventing it's full closure or opening. When you re-install, be sure to aim the clamps to where you can tighten, or loosen them easily, in the future. To identify this part, it should have three or four hoses running to it (two from firewall and two from radiator. It is black plastic, and has a small vacumn canister attached to it. On the 1996 Aerostar it is located right next to the A/C drier, next to the right fender (looking forward from drivers seat).

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The heater control valve is used to shut off hot coolant from entering the core when the heater is in the off position. A heater control valve can be actuated by either a vacuum line or a cable from the vacuum heater control valve to the heater core. This hose should be warm; if not the heater control valve is stuck and needs to be replaced

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The 1995 Aerostar control for the heat uses cables to move the control valves. Start by checking to see that the temperature sliding control is moving properly, and the cable is adjusting the valve for the coolant flow.

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Thermostat is missing or stuck open, coolant level is low, heater core is plugged or heater control valve is stuck closed.

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The heater control valve is stuck open.

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