Please help with blower motor problem - Chevelle Tech
Electrical & Wiring Troubleshooting electrical problems.

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post #1 of 5 (permalink) Old Apr 3rd, 16, 10:08 PM Thread Starter
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Please help with blower motor problem

1971 chevelle (Malibu) it was an A/C car from the factory however the compressor was removed when the new engine was installed so some of those parts are no longer present. The controller is still an A/C control unit.

Just picked the car up Friday and I'm striking out diagnosing the problem with the heat, or lack there of I should say. Basically what I have going on is... nothing, not matter where the fan switch is positioned low-high the blower motor does not come on.

Let me start of with what I have done so far based on my searches of this site.

First I checked the inline fuse on the orange or perhaps it was yellow wire that runs along the firewall. This was confirmed to be good and I have power on both sides of the fuse. Then I moved on to the (I assume) relay that the wire continues into. The harness that runs into the relay looks like it has seen better days, almost like it experienced high heat at some point and started to melt a little bit, wires going into it are a little brittle but appear intact. I then continued to the purple wire which runs into the blower motor, checking that with a test light I found that no power is making it to this wire with the fan on high. At this point I backed up to the relay again and unplugged the wiring harness from it. I then jumped the purple wire direct from the battery and the fan kicked on at about 1billion RPM lol.

I did notice that one of the wires to the Ambient switch has been cut but with the car no longer having A/C I don't think this should matter.

Based on this it seems to me that power is not making it to the purple wire. So whats my next step? Do I just replace the relay and hope for the best or is there a way to test the fan switch? Do I replace both? Is there anything else I should or could test?

It you guys say replace the relay which one do I get, looking at OPGI there are a few different relays how do I know which one?

Any help or suggestions are much appreciated!

Thank you all in advance!

p.s. Sorry if this was long but I wanted to be as through as possible.
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post #2 of 5 (permalink) Old Apr 6th, 16, 1:28 AM Thread Starter
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Re: Please help with blower motor problem

Little update,

I tore through old posts on here and found tons of great info. I found that some of the harness plugs had slightly melted and corroded causing my issues with the blower motor not getting power. Wired in a new 30amp bosh relay and the fan is up and running...BUT although I can not hear the fan spinning at different speeds based on the switch location there is barely any air coming out of the vents. Further digging found that none of the vent position doors seem to be responding when I change location of the control switch. I have the dash pad off an everything looks to be in order as far as the control unit goes but I dont know how to test the vacuum actuator (Im calling it that but the round disk that the vacuum hoses all plug into)

Any advice on this would be much appreciated. I cant even figure out where the air from the blower motor is going but it doesn't seem to be in the car.
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post #3 of 5 (permalink) Old Apr 7th, 16, 12:09 AM Thread Starter
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Re: Please help with blower motor problem

Good talk Russ
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post #4 of 5 (permalink) Old Apr 8th, 16, 7:20 AM
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Re: Please help with blower motor problem

PM and e-mail sent.
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post #5 of 5 (permalink) Old Apr 8th, 16, 11:43 AM Thread Starter
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Re: Please help with blower motor problem


Thank you very much for the email. that is a huge help!
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