Change the climate control vacuum valve motorcraft yh-571

Do you have Manual Climate Control System or Dual Automatic Temperature Control System ?
The temperature control switch:

• is a potentiometer that outputs a variable voltage to the temperature blend door actuator to set the position of the temperature blend door.
• initiates closing of the heater control valve. When set to full COOL, a lever on the temperature blend door pivot shaft depresses the pintle of the heater control valve vacuum switch. The heater control valve vacuum switch then applies vacuum to the heater control valve, closing off engine coolant flow to the heater core.
• is serviced only with the climate control assembly.

You may have disturbed something when changing the actuator , the vacuum switch o vacuum hose .

HAVC Vent Motors under the dash

You can get Motorcraft parts from Amazon
about $33.00 each

There are several motors

On the motorcraft web site they list the
part #'s & have a diagram of which ones
go where

Hello! it's my job to make things as easy for the customer as possible...Therefore I must ask why you want to replace the heater switch? Is it because you have lost one or two of the switch speeds? Your vehicle is noted for loss of the Blower Motor Resistor...
Changing the Heater switch means removal of the Climate Control Assembly which is not the easiest of jobs...I've included the process...But are you sure the blower resistor is OK? If you have lost 1,2, or all blower motor speeds it's more than likely the Resistor pack. And a lot easier to change...
Guru...saailer


Remove climate control:

1. Remove the instrument cluster finish panel...
   

1. Remove the 3 climate control assembly screws...

1. Disconnect the climate control assembly vacuum connector...

1. Disconnect the 5 climate control assembly electrical connectors...

1. Remove the climate control assembly..

Removal of blower motor Switch:

1. Remove the climate control assembly.
   

1. Remove the blower motor switch knob.

1. Remove the blower motor switch.
   1. Remove the screw.
   1. Remove the blower motor switch.

Removal of blower motor Resistor:



Blower Resistor is under the battery tray...

MOTORCRAFT Part # YH1698 ...cost $25



Guru...saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

Assuming you have vacuum controls at the heater control head, you have a classic vacuum leak in the hose from the engine intake manifuold to the control head, or the vaccum storage canister somewhere in the engine compartment. It is required to fail to defrost by law.

Climate Control Assembly
The climate control assembly has 3 system controls:

• The function selector switch combines a vacuum selector valve with 2 electrical switches to supply battery positive voltage (B+) to the blower motor control circuit and the A/C clutch circuit (if equipped).

Vacuum Control Motors
The 2 vacuum control motors:

• are actuated by vacuum from the function selector switch.
• position the plenum doors to direct system airflow to the vehicle's interior as determined by the function selector switch setting.

The vacuum reservoir is behind the driver fender well, black plastic ball.

If you have diesel, then you will have a vacuum motor under the hood.

please rate if this helps.

I would say either blend door issues or a vacuum control valve, heater control valve or a vacuum hose to the heater system is leaking. I would start to suggest. You are correct in checking the blend door. A computer scan should tell you what temp the climate control thinks it is in the passenger compartment. It may be a thermostat problem giving the climate control a false reading. Your blend door is controlled by a servo motor under the dash. You can remove the servo and watch to see if it moves when you change the temp setting from heat to cool. Also, you should be able to manually move the door to the heat position and see if you get heat.

MAKE SURE BLOWER MOTOR OPERATING IF NOT CHECK FUSE AND RELAY.ALSO CHECK HVAC FUSE THIS CONTROL HEATER + AC CONTROL SWITCH AND MODE SELECTION FOR OPENING AND CLOSING HEATER DOOR OR HEATER CONTROL VALVE AND AC+ DEFROST AIR DOOR.IF BLOWER AND HVAC FUSE OKAY.IF YOU HAVE MANUAL HEAT CONTROL MAKE SURE MODE SWITCH IS RECEIVING VACUUM. YOU HAVE TO REMOVE HEATER CONTROL SWITCH AND CHECK TO SEE IF GETTING VACUUM GETTING TO SWITCH LOOK FOR BROKE DISCONNECTED VACUUM LINES IN THE DASH AREA.IF YOU HAVE CLIMATE CONTROL.YOU COULD HAVE A FAULTY ELECTRICAL HEAT DOOR ACTUATOR.SOME CLIMATE CONTROL CARS HAS THE CLIMATE CONTROL PROGRAMMER HAS TO BE REPROGRAM BEFORE THE HEATER AND AC WILL WORK AGAIN.YOU NEED A DEALERSHIP SCANNER TO CHECK IT OUT.BUT IF YOU HAVE MANUAL CONTROL CHECK TO SEE IF YOU GETTING VACUUM.IF YOU GETTING VACUUM AT HEATER DOOR VACUUM ACTUATOR OR HEATER CONTROL VALVE EITHER ONE OF THOSE COMPONENTS COULD BE FAULTY.WARNING YOUR VECHICLE HAS AIRBAGS YOU HAVE TO DISARM THEM BY REMOVING FUSES WAIT 20 MINUTES BEFORE WORKING ON DASH AREA.YOU HAVE TO CRANK CAR UP TO CHECK TO SEE IF YOUR HVAC GETTING VACUUM.

The valve (called the heater tap) which controls the hot water flow works from engine vacuum. The climate control unit turns vacuum on to close the valve and turns vacuum off to open it, if the vacuum tubing or vacuum service valve has failed, the tap will be open allowing hot water to flow. The same result applies if the heater valve itself has failed (which they do --regularly) Trace the water hoses from the enginebay firewall under the hood and you should find the valve. Check for cavuum at the valve with the climate control set to its coldest setting. If you have vacuum at the valve, replace the valve. No vacuum points to the loss of vacuum source or a faulty vacuum service valve with will be electrically operated from the climate control. Trace the vacuum hose from the heater valve back to the vacuum service valve and check if the valve has vacuum supplied to it. No vacuum means a vacuum hose has blocked, has a hole in it or has been removed from the manifold. If the electrical valve has vacuum, check for power. If power is present but still no vacuum at the heater tap, replace the service valve. If power missing, check fuses. If both wires to the valve show power present, have the climate controll unit checked by a professional..

the vacuum line in broken, check for same, start fromthe engine compartment, check to make sure the a/c doors are not jammed. check all fuse and relays

Car manufacturers use the defrost mode as a default for safety reasons. Being they want you to be able to defrost the windshield no matter what. So when something goes wrong the system automatically goes to the defrost mode. You most likely don't have the vacuum hose connected under the dash at the climate control assy. Or if this vehicle doesn't use the vacuum hose style you may have not plugged in one of the connectors under the dash or behind the climate control assy. Good luck.

something wrong with clima control ,check the thin plastic pipes have a vacumn in them ??if all else fails wedge the flap open as tis so dammed cold evan here in spain.