I have replaced the defrroster motor resistor, but nothing. We have checked all peertinent fuses, all good. No defroster still in Michigan with 20 degree mornings that could be a real problem . Can anyone tell me where to look next
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Re: Window defroster not running
Locate wires going into the motor, and with a 12vdc test light, probe one wire at a time for power when switch on, low, med, high. If you get power there, it's your motor, or bad ground. Simply use a jumper wire from known good ground and rub or attach it to metal of blower motor, to test for poor ground, with fan switch on. If no power there, I suspect you have a relay in line too, perhaps shows it in owners manual, in fuse box?
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I noted your question. You said that NOTHING is coming out of the VENT. Do you mean the interior vents normally for heat and air? Does air blow out of your dash defrost vent? Does blower motor work continuously? If so, I suggest that you check fuse panel at driver's door. If you have your owner's guide, look on pages 251 and 252. 251 shows your interior fuses. 252 shows description for Fuse #9 (10A). You have numerous 10A fuses. #9 is the lowest fuse perpendicular to Fuse #10 (15A). If it is blown, you have some sort of resistance in one of 4 things RUN BY THE FUSE. I went to my mechanic and he told me that the Blower Motor Control Resistor behind the glove compartment was bad. I replaced it (125 dollars) and it was not the problem. Check the fuse. Is it blown? Replace and the system may work normally. If it continues to blow please get back to me. If the system works after replacement, please respond.
You can jumper the fan motor to make sure it runs and if it does then look at the switch or resistor. You can also remove the resistor and omh acrossed it to make sure that it hasn't blown the fuse on risistor.
Using a test light, check for power at the blower motor connector. If thereis power there, replace the blower motor. If there is no power there, it could be the blower motor switch or the blower motor resistor. The most common is the blower motor resistor.
Check the blower motor fro good connection, power and ground. Hot wire it to the battery and see if it runs. Check the blower fuse, relay, switch and resistor pack. blower and rear defrost circuits are totally unrelated.
Check the blower motor speed control resistor pack is ok.
(The resistor pack is usually located in the blower fan ducting in the air flow).
Check condition of electrical connection terminals on the blower motor circuit - these terminals pass considerable current and over time may fatigue overheat and loosen.
Check operation/replace any blower motor control relay,
Check the blower motor will run if +12v directly applied to the blower motor.
Check operation of the blower motor speed control switch is ok.
Check fuse for blower motor, it is a 30amp fuse behind the plastic panel that is to the left of steering wheel, you must open the driver door, open up the fuse panel, I believe the 30amp is the only 30amp fuse in there, If it is blown replace it, then try the heat again. If nothing or fuse blows again, check the blower motor resistor. This is located under the glove compartment. Do a search on google if that is the case, I was able tofind a solution by putting in "blower motor resistor" ended up buying one for @ 30$.
Hi: Sounds like a possible heater resistor problem. First check to see if heater fan working, unplug heater under hood and put 12 volts to it from the battery with a wire (single black wire running to back of fan). If works then problem probably the resistor which is located on the fan housing under the hood to the right of the fan. The resistor has wires to it running from the heater fan, 2 - 7mm screws holding resistor in place, check resistor to see if any of the 3 elements are melted off, if so replace. Note: Rear window defrost has nothing to do with heater fan. Hope this helps...