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Defroster/Heater fan doesn't come on

KennyCuda

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When I put the defroster switch on nothing happens the blower motor doesn't come on either high or low. I pulled the plug off the back of the switch and it getting power how do I know if the switch is bad or the blower motor itself I don't want to change things I dont have to especially at todays prices? thanks
 

KennyCuda

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was reading about the blower motor removal its a big job
 

Katfish

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Shouldn't have to remove to test, connect the 12V jumper to the wiring harness of the blower.
 

KennyCuda

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I tested continuity in the switch and hav it on high and low. I put 12 volts to each side of the harness that goes to the blower motor and nothing. Could it be a bad ground? and can I get to it without pulling everything out, Do the nuts that hold the motor in the engine compartment act as a ground > Where is the resister located?
 

BriceRoad

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I tested continuity in the switch and hav it on high and low. I put 12 volts to each side of the harness that goes to the blower motor and nothing. Could it be a bad ground? and can I get to it without pulling everything out, Do the nuts that hold the motor in the engine compartment act as a ground > Where is the resister located?

KennyCuda, my car is taken apart so I took some pictures. You can easily access the connector at the heater box if you remove the glove box. I checked my FSM and the FSM does not show where the resistor is. I believe the resistor is inside the heater box. The FSM just says there are two wires going to and connecting at the heater box (high and low) but my box has 3 connections. My guess is the 3rd connection is for the ground. I am not sure why the FSM does not show the 3rd wire. Perhaps it is shown in a different schematic than the one I was looking at. The 3rd wire may eventually go through the nuts that hold the motor to ground but I am not sure about that. Maybe someone else can chime in.

In the picture below arrow A is pointing to where the hot wires go from the High/Low switch; arrow B is pointing to where the 3rd wire goes, the wire I believe to be ground; and the orange arrow C is pointing to the 3rd wire. It is hard to see. I am holding the connector (sorry about it being blurry) which should be the High/Low hot wires. It's the only wire connector that will fit my heater box. I would check for 12V on each one of these wires at the connector. If you have 12V at the connector then I would look for a ground problem or a motor problem. Even if the resistor was bad it should still work on High. Also looking at the connector in my hand, the bottom connection is the High and the top connection is the Low. If I am wrong about any of this please correct me. I am not an expert. I hope this helps. Good luck and keep us posted.
HBWire0111.jpg
 
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KennyCuda

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Thanks what a big help after i checked the switch which is good I found out the dark green wire is positive. On the top of the box you show 2 wires go to one side and one to the other. I tested the 2 wire side dark green wire and im getting power there which plugs into the resister which mounts from inside the box just the tabs stick out, Then I checked the single side which is dark green and im getting power there also which tells me the resister is good,( the single plug goes right to the blower motor) Then I said if the motor is getting power it might be a ground so I used my test light as a ground and scratched the ground lead hoping the motor would run but it didn't so im 99% sure the motor id bad, bummer
 

Challenger RTA

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Use the hammer. It's might be stuck. Place a block of wood on the back side to back it up, where you can smack it.
Remove the resistor and you might be able to spin the impeller.

20200228_211120.jpg
 
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KennyCuda

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I hit it with a rubber mallet didn't help. Can I replace the motor while its still in the car and take the front part of the case off or do I have to remove the whole box, im hoping the front will split apart from the back
 

mrmopar340

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I hit it with a rubber mallet didn't help. Can I replace the motor while its still in the car and take the front part of the case off or do I have to remove the whole box, im hoping the front will split apart from the back
If it's an A/C car the fan blower comes out on the engine side. Not A/C you got to pull the box.
 

KennyCuda

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so to change the motordoesthe heater core have to come out or can it be split and leave it in its old should probably replace it
 

KennyCuda

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ok hopefully it not to hard to get out any tips on its removal or is it pretty straight forward- I know the AC cars are a pain to remove
 
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