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Blower Motor Dead--need Help

slydog39

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slydog39 Enthusiast

slydog39

Posted
Posted

This is not a new issue to many, but I am having trouble diagnosing and fixing my non-working ac blower motor (front unit). The blower began cutting out at various times and various speeds. Then is stopped working all toegether at any speed. I checked for voltage at the power lead that attached to the motor itself and was getting 11.8 volts. so I replaced the motor. Now the new motor does not work as well. ( I later checked my old motor by running power to it's terminals from the battery, and it jumped to life.)

 

I also replaced my blower motor relay. When I check for power at the blower motor power lead, I get voltage at all but the hi setting.

 

Could this be a resistor issue? Is it a switch issue? I am no electical genius, so any help would be appreciated

DMurphy Enthusiast

DMurphy

Posted
Posted
This is not a new issue to many, but I am having trouble diagnosing and fixing my non-working ac blower motor (front unit). The blower began cutting out at various times and various speeds. Then is stopped working all toegether at any speed. I checked for voltage at the power lead that attached to the motor itself and was getting 11.8 volts. so I replaced the motor. Now the new motor does not work as well. ( I later checked my old motor by running power to it's terminals from the battery, and it jumped to life.)

 

I also replaced my blower motor relay. When I check for power at the blower motor power lead, I get voltage at all but the hi setting.

 

Could this be a resistor issue? Is it a switch issue? I am no electical genius, so any help would be appreciated

 

Sure sounds like the resistor. It's a cheap enough part to replace although sometimes they can be a bear to get to. I just did mine on my 95. The blower would only work on high. Resistor cost was about 16 bucks.

slydog39 Enthusiast

slydog39

Posted
  • Author
Posted

It turned out to be the fan switch itself. A $18 part. I still do not understand why I was getting a voltage reading at the fan power lead, but the switch was bad. In any case, the new switch cured the problem.

 

Thanks for the replys

bill190 Enthusiast

bill190

Posted
Posted

With "intermittent" problems, it could be that when you measured the voltage, it suddenly decided to work! Other times like with a poor connection, you will get a voltage, but when you place a load on it (connect to fan), there will be little or no voltage.

 

One trick with intermittent problems is to connect test wires (at a certain point) to a multimeter and have this in the vehicle as you drive around. Then when the problem occurs, you can look at the multimeter and see what it is reading.

 

When I previously did repair work (not automotive), a customer would have an intermittent problem and when I walked in the door, you could bet everything would be working just fine! :seeya:

minibike132 Senior Enthusiast

minibike132

Posted
Posted

First step is to stop using a multimeter for this circuit. It can lead down the wrong path. You are trying to drive a high load or motor. Use a test light instead, that will tell the real story about weather or not there is the needed available voltage. A very poor wire will carry 12 volts as read on a meter but not with the amperage necessary to drive a motor.

  • 7 months later...
tdweiner New Member

tdweiner

Posted
Posted

I'm having a similar problem to this. I have an 05 Sierra Denali. The problem started when I couldn't get the blower to work on any speed. I did some searching online and learned about the resistor problem. According to what everyone else was experiencing for symptoms I figured this was my problem. I ordered the resistor kit from MotorCity and proceeded to replace the resistor and connector, but this did not resolve the problem. I did the multimeter test and found that the connector before the resistor was getting 12v. After plugging in the resistor and checking the leads that connect to the motor I was getting about 4.75 volts on the low setting and about 5.5 volts on the high setting. I then stopped down to the local GM dealer to see what the outputs should be. When I told them what I was getting they said that should be correct and that the blower motor need to be replaced. Upon replacing the blower motor my problem still is not fixed. I put the old blower motor back in. Now the other problem is that I can't switch the blower outputs. The only place that air moves is the defrost vents and only a minimal amount since adjusting the blower settings does nothing. I checked fuses as well just to make sure that nothing was malfunctioning there. I'm baffled as to what the problem is. Do you think that it could be a problem with the switch on the panel and would this cause the problem where I can't switch where air is flowing to? Thanks.

ken1mod Senior Enthusiast

ken1mod

Posted
Posted

Gentlemen,

 

I agree with the guys that troubleshoot. Replaceing parts one by one is not the answer. One must find the one defective part and replace only that one. I usually run out of money before parts if I do not use a meter to find the real problem.

 

Ken

KENNHON Enthusiast

KENNHON

Posted
Posted
First step is to stop using a multimeter for this circuit. It can lead down the wrong path. You are trying to drive a high load or motor. Use a test light instead, that will tell the real story about weather or not there is the needed available voltage. A very poor wire will carry 12 volts as read on a meter but not with the amperage necessary to drive a motor.

 

Well, Mr. Sparkstest, you have rattled my brain.... i had forgotten the shortcomings of multi-meters[specially digital]; Thank you, Sir!!!

 

And thanks to ALL who reponded to my call for help with my'96 blower prob[only had high speed];the prob. was just what you characters said-Resistor- What you didn't tell me was how freakin little room there is to get it out, and use your fingers to get it in-- on TOP of evap. housing-behind high speed relay[you neglected to tell me that part]!!! so now i have 30 million cuts on my fingers and arms! where do i go for 'Restitution'??? LOL! Really, thanks again, saved me 50 bucks, or MORE at a repair shop!

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