Topic: Blower motor stopped working

[OrangeCrush79]

Hi everyone, I recently had a problem with my blower motor in my non a/c 1979 Trans Am. It stopped working when I was lowering the blower speed. I turned on the heater to take away some of the heat from my engine while waiting at a stop light. I lowered the blower speed when I started moving again and it quit working. Now I get nothing when I turn on the blower.
      I checked my fuses and they all seem okay. What else could fail and cause the blower not to work? I tried looking at my 79 service manual, but I'm still not sure what to do to find the solution. Any help would be appreciated, Thank You.

[Wallington]

If you lose speeds on the fan, initially,  then your resistor has gone on that speed. This can sometimes affect others if the broken wire  sticks onto the other coils creating a short. Check there first anyway.

[OrangeCrush79]

Hi Aus78 Formula,       Well, I replaced the blower resistor hoping that the blower would start working. Unfortunately, it still isn't working. What else could be causing the blower motor not coming on? I checked the fuses again and they are okay. How do I troubleshoot the problem? Was told by the counter person that it could be the blower motor. Can you check the blower motor without taking it out? Is there a relay in the circut and where would it be located?

[Stringer]

As Aus78Formula said if you loose the fan on the low speeds it is usually the resistor.  The power for the fan runs through the resistor for speeds 1, 2, and 3.  On high, the resistor is bypassed and it gets full power through the relay (located on the side of the A/C housing next to the resistor). 

There is a power coming from the resistor that is attached to the relay, but usually if the relay is out you will have the 3 lower speeds and not high.  There is also a power wire coming from the alternator going to the relay but it is also for the high speed fan (disruption in power from this wire will only affect the high speed fan - as that was the problem with mine).

I have attached the wiring schematic for you to examine.  Hope this helps.

[OrangeCrush79]

Hi Stringer,
            I lost all speeds when the blower went. Nothing! I don't have a/c in my car so I don't know if there is a relay and where it would be located. I already installed a brand new resistor and still don't have the blower working.
           What else could cause the blower motor for not working? Can the blower motor be checked without removing it? I want to check it to see if it still works. If it doesn't - then that might be the problem. Anybody have the procedure on how to check to see if the blower motor still works?
     

[Stringer]

OrangeCrush79 there will definitely be a relay.  The blower motor wiring works the same with or without the A/C.  Where the relay is located with on a no A/C car I am not sure...it could be behind the inner wheel well next to the blower motor.

The only way I know to test the blower motor without removing the inner fender well is to locate the power lead that goes to it and attach power directly from the battery.  The blower motor itself only has two wires going to it - a ground (attached to the firewall at the motor) and a power wire (that comes off the relay).

If you cannot locate the power wire you may have to pull the inner fender well.  It isn't too difficult to remove and put back. You may have to wrestle with it a while but you will figure it out. 

To remove:
- Remove all bolts that attach the inner fender well
- Push the well up and back to clear the fender lip
- Pry the front section of the well over the front portion of the sub frame
- Pull the front of the well down until it clears the sub frame then rotate it clockwise and it will come out. 

To put it back:
- Place the rear of the well in first
- Rotate counter clockwise until it binds on the finder lip
- Push the well up past the sub frame
- Use a screw drive to pry between the fender well and fender to get the well to set behind the finder lip
- Bolt it back in

[OrangeCrush79]

I plan on checking the blower just like you mentioned here this weekend. Other priorities are causing me to wait until then to work on the car. Thanks for taking the time to respond to my question. I will give you my results after I work on the car.  Jon Wiz

[OrangeCrush79]

Hello Everyone,
           I'm sorry that I haven't gotten back in quite awhile, but health reasons put my repair on hold. I checked to see inside the car and the only relay I found was near the glove box. I thought that this was for the rear window defogger. Or is this for the blower motor?
     I found the wire that powers the blower motor. It has a plug that disconnects in the middle of the wire. One end goes to the blower, the other end goes into the firewall. I will try running a wire from the battery to this wire to see if the blower works.
     Does the fan speed switch need to in the ON position while I do this? Thanks for all your help so far, I would like to have heat in the car. The last 2 car shows of the season and the temps will be in the upper 50"s here in NJ.            John W

[conan31214]

I would just go over the process of elimination. There's not that many things to go through in the blower motor system and can probably be found with a test light. See if your getting power to the motor if you have to just run a quick hot wire to the battery and see if it spins. If it does it's something in between that right up to the fan switch. Electrical diagnosis can give some of the biggest headaches but this one is pretty cut-and-dry. Good luck

[Wallington]

The fan switch only has speeds, not on or off. It always runs.

[OrangeCrush79]

Hello All,
              I connected the jumper wire from the battery to the blower motor and it came alive! I will try checking inside the car next by using a probe light to see if I'm getting voltage at the resistor. After that I'll check the fan switch for power. 
        Does anyone know if there is a relay (one of the silver metal boxes) on the fuse block that controls the power going to fan switch, resistor and then the blower motor?
        Can the fan switch fail - causing no power going to the blower motor?
             May have to wait awhile because its supposed to get plenty cold here in Jersey the next week. Thanks to all of you for the replies and helpful responses. Still having some health issues also in the way of working on the car.      John W 

[Wallington]

Anything can fail, but more commonly failed relay and resistors or disconnected power/earth from shoddy air con removal. Does yours have air con, or the blower motor relay on the  firewall box?

[OrangeCrush79]

My 79' Trans Am does not have Air Conditioning. Since it doesn't have A/C, I don't see a relay anywhere close to the blower or the A/C delete cover. Tried using my voltmeter to see if there was juice on the blower motor wire that comes out of the firewall. No power was registered there, so that means my next step is to check inside the car. If there is power inside, than it's the wire that may have a break. If not, then the mystery continues......
     I still don't know where a possible relay is that's mentioned on A/C cars?