'94 heat system electrical HELP
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'94 heat system electrical HELP
Hi, I was wondering if anyone knows where to find a diagram for the wiring for the heat system on a '94 250. Problem I'm having: heat only works on highest setting, and only through the defroster. I checked the wiring going to the fan speed selector, and of course only high has power. As for the other problem, no matter what setting the switch is on (floor, vent, mix, or defrost) the heat only comes through the defroster. If anyone has any possible explanations, that'd be great. thanks!
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How can I check those hoses for leaks? As for the switch, theres no power going to it other than high speed, when I took it all apart i checked for current in the other wires before buying a new switch. i read a few other posts saying something about a blower motor resistor needing replacement in this case. Where would this be located? Does this seem like a possible explanation?
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Joined: Jun 2004
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From: Central NY
This should help 
Originally Posted by alchymist
Usually inside the fan housing - a short coil of resistance wire (or 2 coils if multi speed. Mounted on a little insulator in the air stream. Some of them are on the back side of the electrical connector to the fan motor (if the connector is mounted to the housing and not the motor), and can be reached by taking out the connector mounting screws. Your mileage may vary.
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The resistor is located under the hood on the outside of the heater box. 2 screws hold it in.Check your vacuum lines at the heater control
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From: SC lowcountry
If 94 is like 95 heat/ac vacuum source starts at vacuum tree on intake goes to a vacuum reservoir integral with the evaporator housing and then up to the harness at passenger side cowl. Look for cracked black vacuum line going into passenger comp't/feel for vacum at end of source hose; there are connectors inside the cab at kick panel passnger side and at back of control unit.
Just replaced my vacuum control switch, leaking thru. Good luck.
Just replaced my vacuum control switch, leaking thru. Good luck.
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From: SC lowcountry
Also the white plastic hose going to the door actuator on top of the heater core housing at passenger side cowl under hood is famoous for deteriorating and will appear ok but is disintegrating as it comes out of the harness from dash. This will decrease available vacuum to operate other a/c actuators. just get 1/8" I think rubber vacuum hose and splice in over bad area of plastic hose.