Fan Blower Speed - only High Works
05-20-2012, 11:43 PM
#21
8th Gear
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Location: Florence Arizona
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Just wanted to poke my head in here and say thanks to everyone in this thread. Wilcox Corvette, your '82 diagram helped me figure out my relay was bad.
Thanks again!
Thanks again!
05-21-2012, 11:38 PM
#22
'82 fan only works on high speed
sorry for the late response - i was on vacation but to answer your question i never did get mine to work - so you are saying it is a relay? Where is it located and do you have the part number?
Thanks!
Thanks!
05-22-2012, 01:44 AM
#23
8th Gear
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No problem! But you said you replaced the relay, no?
I found this good picture of the locations of the relay and the resistor module on the 'net. It's looking from the right side of the car just in front of the firewall. I got a replacement relay at O'Reilly Auto for $7.49 and the part number is 35777.
Here's a picture of it.
The way it works.. referring to the picture:
The left vertical lug (purple) is connected to the middle vertical lug (blue) when there's no voltage across the horizontal lugs (any fan speed other than high). You should also see this when the relay is disconnected. Mine was not doing this, so I knew it was bad.
OR
The left vertical lug (purple) is connected to the right vertical lug (red) when there is voltage across the horizontal lugs (high fan speed). Mine was only doing this.
Hopefully this helps!
05-22-2012, 07:55 AM
#24
'82 Fan blower - only high works
Yes - now that i see these pictures i did replace this relay, and the resistor and the selector switch. That is why i stopped - none of these fixed it. Not sure what else to do!?
05-22-2012, 11:54 PM
#28
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Sorry, I should have continued.
I'd start by testing the new stuff, make sure it actually works right. A continuity tester should work too.
Test the relay like I mentioned.
Measure the resistance across the whole resistor array. I get around 2.4 ohms. A continuity tester will probably just show continuity with that low of resistance.
Wilcox Corvette's YouTube video on testing the fan speed switch is here:
http://www.youtube.com/watch?v=h17GkrfP9rA
I'd start by testing the new stuff, make sure it actually works right. A continuity tester should work too.
Test the relay like I mentioned.
Measure the resistance across the whole resistor array. I get around 2.4 ohms. A continuity tester will probably just show continuity with that low of resistance.
Wilcox Corvette's YouTube video on testing the fan speed switch is here:
http://www.youtube.com/watch?v=h17GkrfP9rA
Last edited by TEA-Time; 05-23-2012 at 12:09 AM.
11-19-2013, 04:24 PM
#29
Naples FL
I am having a similar problem on my '78...my system was working fine...until I changed out the a/c control panel.....it seem it only works at one speed...except when I put it on "high" it shuts down...the fan will blow at high speed only in low & medium...and even if the control panel is off...it I toggle the fan switch to off it will run @ low speed as it should with the system off...I even swapped out the control panel and the fan switch and no change...the resistor's have both been changed...I had a problem in the past in which the fan would not work on high...but all other speeds were okay...I ran a direct ground for high and it solved the problem....this was several years ago...now this...any suggestion?
11-19-2013, 08:34 PM
#30
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St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
So.. let me see if I have this correct..
When on High you have nothing.
When on Low and any other speed you have high?
When on High you have nothing.
When on Low and any other speed you have high?
11-20-2013, 04:11 AM
#31
Naples FL
Yes, I also changed the rear defroster switch... If that matters... Thanks
11-20-2013, 07:23 PM
#32
Naples FL
Any thoughts??
11-20-2013, 09:16 PM
#34
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St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Thoughts.. heck yeah.. I pull up a chair, fix me a strong drink and tell you....
It's impossible for it to be on high speed in any position but high if the wires are good.. so you're in trouble..
Just kidding..
The only way for this to possibly happen would be:
If the relay was toast. how to test is posted below.
The switch in the console is defective. You said you replaced this.
You have a short somewhere. we move to finding that later.
I see where you replaced the console switch and still had the same problem so lets take a look at at the relay.
With the relay un-plugged I would test for continuity between 101 and 65. You should have continuity here with it un-plugged.
I would then test for continuity between 65 and 2. You should not have continuity there. If you do, replace the relay, or repair it.. (I have a video on my site for taking them apart).
To take this a step further, power up the relay with a 12 volt jumper at 52 with a ground on 150 and see if you have continuity between 2 and 65. With power you should have continuity... and it should drop off 101 and 65.
Post back.. I'll check tomorrow morning.
Willcox
It's impossible for it to be on high speed in any position but high if the wires are good.. so you're in trouble..
Just kidding.. The only way for this to possibly happen would be:
If the relay was toast. how to test is posted below.
The switch in the console is defective. You said you replaced this.
You have a short somewhere. we move to finding that later.
I see where you replaced the console switch and still had the same problem so lets take a look at at the relay.
With the relay un-plugged I would test for continuity between 101 and 65. You should have continuity here with it un-plugged.
I would then test for continuity between 65 and 2. You should not have continuity there. If you do, replace the relay, or repair it.. (I have a video on my site for taking them apart).
To take this a step further, power up the relay with a 12 volt jumper at 52 with a ground on 150 and see if you have continuity between 2 and 65. With power you should have continuity... and it should drop off 101 and 65.
Post back.. I'll check tomorrow morning.
Willcox
11-22-2013, 05:19 AM
#35
Naples FL
I am installing a new relay this morning...I will keep you posted...I hope this works! The relay is only about 4 years old...
11-22-2013, 10:16 AM
#36
Former Vendor
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St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Funny.. I took a used one relay yesterday to show you how to test it... and the coil inside was fried.. I took a second one apart and the (80-82 style) and the contact elbow was broke off. LOL.. The 77-79 style is a easy one to repair.. I'm not so sure about the 80-82 style
11-22-2013, 11:42 AM
#37
Naples FL
It worked !!! You are a genius!!!
Thank you!!!!!!
Thank you!!!!!!
11-22-2013, 01:04 PM
#38
Former Vendor
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Location: Jeffersonville Indiana 812-288-7103
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St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Glad that fixed it for you.. 
Willcox
03-27-2017, 02:51 PM
#40
thank you!
Thoughts.. heck yeah.. I pull up a chair, fix me a strong drink and tell you....
It's impossible for it to be on high speed in any position but high if the wires are good.. so you're in trouble.. Just kidding..
The only way for this to possibly happen would be:
If the relay was toast. how to test is posted below.
The switch in the console is defective. You said you replaced this.
You have a short somewhere. we move to finding that later.
I see where you replaced the console switch and still had the same problem so lets take a look at at the relay.
With the relay un-plugged I would test for continuity between 101 and 65. You should have continuity here with it un-plugged.
I would then test for continuity between 65 and 2. You should not have continuity there. If you do, replace the relay, or repair it.. (I have a video on my site for taking them apart).
To take this a step further, power up the relay with a 12 volt jumper at 52 with a ground on 150 and see if you have continuity between 2 and 65. With power you should have continuity... and it should drop off 101 and 65.
Post back.. I'll check tomorrow morning.
Willcox
It's impossible for it to be on high speed in any position but high if the wires are good.. so you're in trouble..
Just kidding.. The only way for this to possibly happen would be:
If the relay was toast. how to test is posted below.
The switch in the console is defective. You said you replaced this.
You have a short somewhere. we move to finding that later.
I see where you replaced the console switch and still had the same problem so lets take a look at at the relay.
With the relay un-plugged I would test for continuity between 101 and 65. You should have continuity here with it un-plugged.
I would then test for continuity between 65 and 2. You should not have continuity there. If you do, replace the relay, or repair it.. (I have a video on my site for taking them apart).
To take this a step further, power up the relay with a 12 volt jumper at 52 with a ground on 150 and see if you have continuity between 2 and 65. With power you should have continuity... and it should drop off 101 and 65.
Post back.. I'll check tomorrow morning.
Willcox
