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Discussion Starter · #1 ·
I replaced the climate control wiring harness in my car last September (old one was hacked to death by the last owner but it worked). I also replaced the motor but it needs it again, it squeals loud and the connections get hot on the higher speeds. One time smoke starting coming out of the dash from the connectors. A new motor would solve that problem. When I had it all back together it all worked for a little while, but after that incident with the dash all but the top speed wouldn't work. I replaced the switch and checked the dash connections and they're all fine as well as under the hood but can't seem to find the problem. I heard the highest speed had it's own circuit or something. I've got a wiring diagram so I could check. Any suggestions? Thanks!

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1970 Chevy Custom El Camino
Originally was & will be Green Mist & Silver w/Green Vinyl Top (now black/black)
350ci/300HP 4bbl & Dual Exhaust
TH-350 - 2.73 Posi Rear - Factory PS, PDB, PW, Tilt, A/C & More
My El Camino Home Page
Also, check out my new 1987 Chevy Caprice Coupe!
Other Restorations - 1969 Snowco Trailer & 1967 Sears Custom 600 Tractor
Team Chevelle Member #995
 

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Shawn, without a long explanation of why Chevrolet chose to use a relay on only the high speed fan position, just check this out. The lower speeds all go through the blower motor resistors which are located in the A/C housing (suitcase?). If you are standing next to the left side fender, you are looking right at it. Follow the heavy wire of the two wires attached to the blower motor back and it will lead right to the blower resistor connector. Make sure it's plugged into the connector first and if it is then check the resistors for continuity. Two little screws and it comes right out of the A/C housing. The wiring from the back of the blower speed switch comes directly from the back of the switch to this resistor assembly and then to the blower motor. The high speed position does have it's own circuit and usually works even though the resistor assembly is fried or even disconnected.
If you find a source for that resistor assembly, let me know. I have found the non-A/C version which only has two resistors but not the A/C version which has three resistors.

Good luck,

Louie Hammel
 

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High speed gets its 12 volts through the in-line fuse. The lower speeds get power from the fuse block. Have you checked to see if you have power through the in-line fuse with everything off?
 

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Shawn,
What John said. I've seen some of the in-line fuse holders start to melt from a combo of underhood heat and the high current that flows thru them. Especially common in mid 70's Chevy's.

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Tino #28 Gold
72 Malibu 350-300,700R4
83 Grand Prix LJ 305
 

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Discussion Starter · #5 ·
The fuse holder in mine isn't there (used harness), I just wired a wire from the old harness to it and it used to work. I've jiggled and checked the connections there and it's fine. I pulled the resistors and replaced them with ones I knew worked but still no luck. Same with the relay just in case but it didn't help. I cleaned the connectors on the switch end but still had no luck. I'll check it out tomorrow and post back. A continuity check would help.
 
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