Blower Motor Dead--need Help

[slydog39]

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]

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.

[dorman68]

The resistor and or pigtail connector are a very common problem, almost a "tune up" part I would say when the trucks reach a certain age.

[slydog39]

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]

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!

[minibike132]

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.

[tdweiner]

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]

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]

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!