Team Chevelle banner
  • Hey everyone! Enter your ride HERE to be a part May's Ride of the Month Challenge!

1 - 6 of 6 Posts

·
Registered
Joined
·
1,063 Posts
Discussion Starter · #1 ·
When I would use the fan before, I'd smell plastic burning in the dash. I thought the switch went bad so I just replaced it today, but it still doesn't work, and now not at all. With the old switch it would work on and off when I jiggled the switch, but only in the two upper speeds. The terminal that got hot and slightly melted the connector on the switch was the upper most one on the right if your looking at the switch from the back. What's the problem here? Bad relay? Dirty contacts?
It worked right after I replaced the whole harness back in September but it was after that when it started smoking (in the dash on that upper terminal)and then stopped working. I traced the wire today, but didn't look at it real close yet, maybe it's shorting out somewhere? What do you think? I know the blower motor works, it was just noisy before (30 years old)when it ran so I'll replace it when I get the chance but it worked, just squealed loud. Anyone have any ideas? Thanks.

------------------
1970 Chevy Custom El Camino
Originally was & will be Green Mist & Silver w/Green Vinyl Top (now 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
Other Restorations -1969 Snowco Trailer & 1967 Sears Custom 600 Tractor
Team Chevelle Member #995
 

·
Premium Member
Joined
·
1,404 Posts
Shawn,
First check out the wire harness closley. Use a multimeter and check continuity against ground to see if there is a short. The wires shouldn't smoke unless there is a short or overload. And I doubt you have an overload situation unless the blower motor is froze up.
The fan speed is controlled by a step resister found in the heater box. Normally on top or in the side. It will be held in place by 2 small screws and is usually light brown in color. When one or both of the coils burn out (brake or open), the fan will only work on one or two speeds.
Sounds like you have more than one problem.
Good luck, hope this info helps.

------------------
FastSS396Man
Brian

69' SS396 Chevelle
L78 396/375hp
M-21 Close Ratio
Cortez Silver
10 year Resto
It's brand new again!
02' Harley FatBoy, Diamond Ice pearl.

[This message has been edited by fastss396man (edited 12-27-2001).]
 

·
Registered
Joined
·
1,063 Posts
Discussion Starter · #3 ·
I'm pretty sure the resistors are alright, I checked them when I installed them in September, but with the harness I did two things differently. Under the hood, the power for the blower harness comes from an orange wire, right? On the end of it there's a strange round metal thing, maybe for a fuse I'm not sure. I spliced another wire on the end of it and ran that to the horn relay where it gets power, using a 14ga? (I know it was the same thickness as the orange one)wire. The other thing is I don't have a compressor, so that wire isn't hooked up to anything. Other than that, everything is the same.
There is this one mysterious purple wire with a black stripe that runs to the control unit in the dash though that melted a long time ago that I disconnected, this runs to the A/C switch (two terminals, clicks on when upper lever is on A/C)on the control unit and goes somewhere in the fuse panel (maybe a power lead). There are two wires that goes to that A/C switch on the control unit, and the purple one combines with a brown one on the connecter. Looks original, but I don't see it in the wiring diagrams.
 

·
Premium Member
Joined
·
2,223 Posts
Shawn

There are two sources of power to the blower. The orange that you spliced and connected to the horn relay is the supply for the high-speed only. You should have an inline fuse 30 amp for this source.

Use a voltmeter or a test light to check the other source. Start at the fuse block, the top right 20 amp fuse is for the heat A/C. With the ignition on you should have voltage on both sides. At the control assembly check for voltage at the master switch. The brown wire comes from the fuse block. The other terminal has a tan and light green with the control lever in any position, except off you should have voltage here. At the blower speed switch the tan wire comes from the master switch you should have voltage here. Place the fan switch to low speed you should have voltage on the yellow wire, medium 1 puts voltage on the light green wire, medium 2 puts voltage on the light blue wire and high puts voltage on the #18 dark blue wire. At the step resistor pull the connector plug check for voltage on the yellow (low), on the light green (med. 1) and on the light blue (med. 2). From the step resistor the #12 dark blue wire will be spliced to a #12 purple wire (it may have a stripe). The purple wire connects to the blower. This completes the circuit for the lower speeds. At the blower high speed relay, with high selected you should have voltage on the #18 dark blue wire. This picks up the relay connecting the #12 orange to the #12 purple, which connects to the blower completing the high-speed circuit.

Actually no blower circuit is complete if you don’t have the blower motor grounded. A #12 black wire is connected to a spade lug at a blower mounting screw. This black wire is grounded to the firewall above the high-speed relay. The high-speed relay will also needs to be grounded a #16 black wire is spliced to the #12 blower ground wire. Make sure all ground connections are clean and making good contact.
 

·
Registered
Joined
·
1,747 Posts
The fact that the blower motor is 30yrs old and squeling leads me to beleive the motor needs to be replaced. You were smelling the result of excessive current due to the blower motor. Replace it. This excessive current probably has caused damage to connections. You will have to figure out a way to clean every connection.

------------------
Steve Strasemeier (70SS 396, Fathom Blue/White Stripes)
My 70SS
 

·
Registered
Joined
·
1,063 Posts
Discussion Starter · #6 ·
Good thinking Steve. I never even gave that a thought, I thought it was the squirrel cage scraping the firewall but I doubt that. The motor I was using before ran fine and nothing got hot, but I was using a homemade harness, not a factory one.

Another thing I noticed looking at it today was there was also a melted terminal on the relay, I think it was the top one. Different color wire though but it was a thick gauge one. I can remember smelling the same smell outside the car after I got out to park it when everything worked before.

[This message has been edited by Shawn (edited 12-28-2001).]
 
1 - 6 of 6 Posts
Top