Heater Switch Problems
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Mountain Pass
Joined: Sep 2010
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Heater Switch Problems
1997 F-250 light duty, heater controls: I'm trying to explain this off the top of my head so bear with me because with regard to the heater's control switches, there's more wrong than right!
Air conditioning: not working.
Heater: working, heater core replaced five years ago, seems OK.
Fan/Blower: only works in "HIGH" position.
Air Flow Direction Switches: only Defrost position works.
Anybody got any hints as to what the problem is? I'm hoping it's an easy fix!
-Mike
Air conditioning: not working.
Heater: working, heater core replaced five years ago, seems OK.
Fan/Blower: only works in "HIGH" position.
Air Flow Direction Switches: only Defrost position works.
Anybody got any hints as to what the problem is? I'm hoping it's an easy fix!
-Mike
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Joined: Jul 2005
Posts: 11,931
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you have several problems. "only defrost" means you have a vacuum leak in the control system. THis can be inside the dash switch, a bad cracked vacuum hose at the firewall infront of the glove box, or a bad vacuum canister inside the passenger fender weill behind the battery... you are loosing vacuum.
SEcond problem is blow only runs on HI. There is a resistor block about the size of an ice cube with 3-4 resistors on it. If 1-2 burn out, you will only have high speed. THe block can probably be seen laying on the passenger side floor, look up under the glove box, look at the heater duct, and look for a plastic block with 3-4 wires attached to it. Some later models had the block ouside by the fire wall, i have been told. I bet yours is under the glovebox.
Why dont the AC work? No coolant is the biggest cause. There is a low pressure switch and when the gas pressure gets low, the compressor will not work. Dumping a can of gas in the system will make it easier to test, but it would be good to have a couple gauges so you know what your looking for.
SEcond problem is blow only runs on HI. There is a resistor block about the size of an ice cube with 3-4 resistors on it. If 1-2 burn out, you will only have high speed. THe block can probably be seen laying on the passenger side floor, look up under the glove box, look at the heater duct, and look for a plastic block with 3-4 wires attached to it. Some later models had the block ouside by the fire wall, i have been told. I bet yours is under the glovebox.
Why dont the AC work? No coolant is the biggest cause. There is a low pressure switch and when the gas pressure gets low, the compressor will not work. Dumping a can of gas in the system will make it easier to test, but it would be good to have a couple gauges so you know what your looking for.
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