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Blower switch


Dsherm112's Avatar
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10-15-02, 03:00 PM   #1  
Blower switch

I have a 1979 Olds Cutlass with a 305. The blower motor only works on low. This should mean the resistor is ok since the resistor reduces the blower speed. But I tested the resistor per the Olds service manual and it failed. I replaced the resistor and it didn’t fix the blower.

I tested the new resistor and it gave the exact same results as the old resistor. Apparently the manual gives an incorrect procedure.

Per the manual, I then disconnected the blower switch connector and ran a jumper from the battery + terminal to the blue wire in the resistor connector. I then tested the blue wire in the blower switch connector with a test light. It tested ok.

The manual than said “repeat test on other wires in the connector”. I wasn’t sure what this meant. It could mean leave the jumper connected to the blue wire and test the other wires in the blower switch connector. Or, it could mean to connect the jumper to each of the different wires in the resistor connector and then check the wires in the blower switch connector.

I decided to do both. With the jumper connected to blue the light lit up on the dark brown, blue and tan. It did not light up on orange. But according to the manual there are only 3 wires in the switch connector. In fact, there are 4. So what does it mean when they all light up except orange?

I then moved the jumper to the black connector on the resistor connector. The insulation quickly melted and smoke poured from the wire. I decided this means the first test was the correct way to do the test, do you agree?

So where does this leave me? Do I have a bad switch since the lamp lights on 3 of 4 wires? Or, a bad wire since it doesn’t light on the orange wire? If it’s a wire, is it the orange? If so, how do you recommend I replace it? Do I trace it back to a connection and replace the entire bundle, or merely replace the 1 bad wire?

Thanks for your help.

Sherm

 
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10-15-02, 06:26 PM   #2  
Joe_F
The connector in the right rear of the engine (the plastic one) turns to dust from heat and fatigues.

Try connecting like wired colors together, eliminating the connector and see what you have. If it works, the connector is melted.

Common problem on GM's of this vintage. Happened on the 79 Cutlass I had .

 
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10-15-02, 06:42 PM   #3  
Clarification

I think you're saying to jump the wires from the resistor connector to the blower switch connector. Is this correct?

If the connector is bad how do I replace it? Does it come with the wires attached or do I splice the wires into the connector?

What about the tests I described in the first post. Do they tell you if the problem is the switch or connector?

Thanks,

Sherm

 
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10-15-02, 07:45 PM   #4  
I guess I cheated on mine. I replaced the blower (just to have a new one) then the resistor. When that didn't fix the problem, I then replaced the switch itself. It was the switch all along, but all were replaced so now I know where I stand on it today.

Kay

 
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10-15-02, 09:20 PM   #5  
Joe_F
No, you missed my point.

Again, the connector turns to dust/melts/oblierates itself with age/wears out/etc due to heat back there.

Inspect the connector closely. Connect like wires together from the connector (may need to cut it out) If things work now, the connector was melted inside. Very common!

You're likely reading the manual wrong.....something doesn't sound right there.

 
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10-15-02, 10:07 PM   #6  
Sherm, I just looked at a wiring diagram and it only shows 3 wires!!! How many speeds are you supposed to have-4? Low,Med1,Med2 and high? For grins, check near your alternator for an inline fuse....my 72 Pontiac has one there for the higher fan settings.

 
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10-16-02, 05:47 AM   #7  
Joe:

I did check the connector as you mentioned above . I tried to do the things in the list you gave me when working on my blower switch problem.

No point in putting new switches, etc. in if the connector you mentioned above if it was melted/rotted.

That is one thing that I haven't replaced yet and it appeared to be newer than the truck. I will get brave and replace it so that I know where I stand on it as well.

I also know that knowing proper ways to test things, as you point out, and DSherm is attempting to do, is the proper way to repair a vehicle. My previous post appears as though I put a "bandaid" on the blower/switch/resistor problem instead of making sure it was a cure. I didn't mean to mislead anyone that way. I was fortunate that it was simply a bad switch and didn't have an underlying cause.

Kay

 
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10-16-02, 06:15 AM   #8  
Joe_F
No problem Kay. It's a common place of failure and should be checked first before replacing parts .

 
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10-16-02, 08:18 AM   #9  
Please clarify

I have inspected the connector closely. It appeears to be ok, it's actually in good shape. If the blower switch tests ok, I'll look at this closer.

I asked earlier about the connection you want me to make. Are you saying to run jumpers fron the resistor connector wires to the blower switch connector?

My blower is always on, then there are three additional speeds. I think this would be a 4 speed switch.

What about the test results I outlined in the original post. Does any one know what they mean? I need to understand these results before I move on.

Thanks,

Sherm

 
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10-16-02, 08:49 AM   #10  
I think he means to cut the old connectors off, and direct wire it together (matching wire colors) to see if the connector is the problem itself. Leave length on both ends to rewire either the old connector (if not the problem) or the new one if it is.

Kay

 
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10-16-02, 10:06 AM   #11  
Joe_F
Kay is correct.

 
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10-16-02, 01:32 PM   #12  
Thanks, I'll let you know what happens.


Sherm

 
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10-16-02, 04:07 PM   #13  
<Per the manual, I then disconnected the blower switch connector and ran a jumper from the battery + terminal to the blue wire in the resistor connector. I then tested the blue wire in the blower switch connector with a test light. It tested ok.

The manual than said “repeat test on other wires in the connector”. I wasn’t sure what this meant. It could mean leave the jumper connected to the blue wire and test the other wires in the blower switch connector. Or, it could mean to connect the jumper to each of the different wires in the resistor connector and then check the wires in the blower switch connector.>


Sherm, this test is to check the continuity of each wire by using a test light. You could do the same with an ohmeter but it would be a little more awkward. You inject a signal, in this case 12 volts at the one end(resistor) and test for the signal(12 volts) at the disconnected blower switch connector. You should have the resistor connector disconnected to make it easier but its not necessary. Once you establish that you have continuity on all wires than your problem has to be to either side of the wiring harness...blower switch or before or on the other end...resistor output/wiring or motor. I'm still puzzled as are you on the wiring diagram, looks like GM left out something. Get back to us.

P.S. Your high blower setting may run through a relay thats usually mounted on the engine side of the firewall.

 
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