Fan switch problems, Please help!! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

71GeneralMotorsCorp · 06-25-2016, 06:58 PM

Hey guys, got a quick question.. I've got a 69 Chevy c10.. Factory A/C truck. (It works too!) Since i've owned the truck, the high speed on the fan has never worked.. Driving it one day, the fan stopped blowing entirely and wouldn't turn on. So, i thought "Simple fix!!" BOY, WAS I WRONG!! I am entirely lost on what to do and what to replace..

Before everything, i checked the fuses! ALL are good and non-blown..

-First, i got a new fan switch from LMC.. plugged it in, and nothing. (NO wiring plug anymore.. P.O. changed to spade connectors..)
-Secondly, Bought a fan motor relay switch and installed it.. nothing.
-next, i decided to see if the fan motor itself was bad, hooked a wire from battery to terminal and it powered on just fine.. ( no noises or vibrations..)
-After that I decided to go back to the plug on the fan switch and test for voltage.. (NO POWER AT ALL ON ANYTHING when switched on..)

Do any of you guys know what in the world could be causing this? it's 103* outside and i'd love my A/C back!! Maybe a wiring diagram of that area would be fantastic..

Andy4639 · 06-25-2016, 07:39 PM

The electrical section has all the wiring schematic's. Sounds like your main wire has come off if you have nothing at the switch.

**Stocker** · 06-25-2016, 08:08 PM

Check this thread http://67-72chevytrucks.com/vboard/s...d.php?t=658012 or search the board for "fan high speed".... there are quite a few threads about this.

Maybe this will help too

**LockDoc** · 06-25-2016, 08:44 PM

-
Bad resistor....

LockDoc

jamesmadconductor · 07-17-2016, 12:30 PM

I stumbled across this thread after realizing that every other thread just dealt with non-functional high fan speed, but low and medium were fine. I believe that we may have the same problem; high used to be intermittent, and now I have no fan at all. I'm thinking that it's actually the resistor, as LockDoc has suggested. Have you tried this yet? I'm likely going to get into it today, if I can find the resistor. Let me know, thanks.

-James-

Thundarr · 07-17-2016, 01:36 PM

My truck had the same exact issue when I bought it. It is definitely the resistor. Once you find it under the dash, its a cheap and easy fix.

Dont forget to do the heater hose shutoff in the engine bay too. It really helps cool the cab down.

Lost of posts on the site about both issues.

Simple10 · 01-16-2020, 06:42 AM

Quote:

Originally Posted by 71GeneralMotorsCorp

Hey guys, got a quick question.. I've got a 69 Chevy c10.. Factory A/C truck. (It works too!) Since i've owned the truck, the high speed on the fan has never worked.. Driving it one day, the fan stopped blowing entirely and wouldn't turn on. So, i thought "Simple fix!!" BOY, WAS I WRONG!! I am entirely lost on what to do and what to replace..

Before everything, i checked the fuses! ALL are good and non-blown..

-First, i got a new fan switch from LMC.. plugged it in, and nothing. (NO wiring plug anymore.. P.O. changed to spade connectors..)
-Secondly, Bought a fan motor relay switch and installed it.. nothing.
-next, i decided to see if the fan motor itself was bad, hooked a wire from battery to terminal and it powered on just fine.. ( no noises or vibrations..)
-After that I decided to go back to the plug on the fan switch and test for voltage.. (NO POWER AT ALL ON ANYTHING when switched on..)

Do any of you guys know what in the world could be causing this? it's 103* outside and i'd love my A/C back!! Maybe a wiring diagram of that area would be fantastic..

What was the verdict? My fan works on high but not medium or low now ..... and if I have it on high, when I stop the truck it won’t start again untill I flick the switch to off position...... it’s doing my head in!!

**LockDoc** · 01-16-2020, 11:26 AM

Quote:

Originally Posted by Simple10

What was the verdict? My fan works on high but not medium or low now ..... and if I have it on high, when I stop the truck it won’t start again untill I flick the switch to off position...... it’s doing my head in!!

If the blower only works on high speed you are probably needing a resistor for the heat blower motor circuit. The reason the blower works on high speed but not low or medium is because the resistor is only used on low and medium speeds. The resistor for the heater is located on or inside the heater box on the inside of the truck, depending on if it is A/C or not. A/C resistor would be item #1 inside the heater box in the first picture below, and non-A/C would be item #4 on the outside of the heater box in the second picture. (from the assembly manual)

Pretty easy to change it. Unplug the connector by prying up on it with a small screw driver working from side to side, and remove the two 1/4" screws. I would recommend using a little dielectric grease on the spade terminals before you plug the connector back in.

LockDoc

toolboxchev · 01-16-2020, 02:26 PM

Part of the problem to look at is the cable adjustment. Watch how hard you move those levers as they are made out of a pot metal.

Look into the Never Pop Kit available in steel levers.

Simple10 · 01-16-2020, 07:40 PM

Quote:

Originally Posted by LockDoc

If the blower only works on high speed you are probably needing a resistor for the heat blower motor circuit. The reason the blower works on high speed but not low or medium is because the resistor is only used on low and medium speeds. The resistor for the heater is located on or inside the heater box on the inside of the truck, depending on if it is A/C or not. A/C resistor would be item #1 inside the heater box in the first picture below, and non-A/C would be item #4 on the outside of the heater box in the second picture. (from the assembly manual)

Pretty easy to change it. Unplug the connector by prying up on it with a small screw driver working from side to side, and remove the two 1/4" screws. I would recommend using a little dielectric grease on the spade terminals before you plug the connector back in.

LockDoc

I’ll check it out �� toolbox .. thanks ...mines air con

Any specific resistor I have to order or ask for?

Simple10 · 01-24-2020, 06:33 AM

I haven’t taken my old resistor out as yet ... but does it look like https://rover.ebay.com/rover/0/0/0?m...2F192417359832

Andy4639 · 01-24-2020, 07:09 AM

Should look like this. #5 in the picture.

Simple10 · 01-24-2020, 11:30 PM

Quote:

Originally Posted by Andy4639

Should look like this. #5 in the picture.

From previous pictures it appears you go in through the top through the glove box, is that right?
Thanks this appears to be it?

Simple10 · 01-25-2020, 12:47 AM

Quote:

Originally Posted by Andy4639

Should look like this. #5 in the picture.

Thanks this appears to be it?

Simple10 · 02-04-2020, 07:11 PM

Anyone know the part number ? I can’t find a fan blower resistor on rockauto.com

Andy4639 · 02-04-2020, 07:59 PM

Not rock auto but here it is.

https://www.classicmuscle.com/392905...hoCqIEQAvD_BwE

Here it is on E bay.

https://www.ebay.com/itm/173648437597

**Sheepdip** · 02-05-2020, 12:20 AM

GM #: 3929055
It was a generic switch used in that era on the A/C equipped trucks, Corvettes, Camaros etc

Simple10 · 02-05-2020, 01:38 AM

Thanks for the help guys appreciate it, rock suck I emailed them asking for a link because I couldn’t find it in their category they wouldn’t send me one And said we created it so you could search pretty much ....to keep the cost down.

Simple10 · 02-20-2020, 07:22 PM

Well the part finally turned up......now off to put it in ...... really can’t see how these fail, it’s just a piece of steal with two springs... be interesting to see the one that comes out.

**LockDoc** · 02-20-2020, 07:44 PM

Quote:

Originally Posted by Simple10

Well the part finally turned up......now off to put it in ...... really can’t see how these fail, it’s just a piece of steal with two springs... be interesting to see the one that comes out.

Let us know if that fixes it or not.

LockDoc

Simple10 · 02-20-2020, 10:10 PM

Quote:

Originally Posted by LockDoc

Let us know if that fixes it or not.

LockDoc

Waste of time did nothing at all

**Steeveedee** · 02-20-2020, 10:55 PM

Those are just resistors. I didn't look up-thread. Did you change out the relay?

Simple10 · 02-20-2020, 11:39 PM

So over this crap ... put the new Part in didn’t work so i left it in there 20 minutes later the air conditioning doesn’t work at all no more cold

Simple10 · 02-20-2020, 11:41 PM

Quote:

Originally Posted by Steeveedee

Those are just resistors. I didn't look up-thread. Did you change out the relay?

I know what they are everything has been tested fan switch works on high but not medium or low which indicates it is a resistor when it’s not

Simple10 · 02-20-2020, 11:51 PM

Oh well got the aircon back on cold ... oops plug fell off

06-25-2016, 07:39 PM	#2
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: Fan switch problems, Please help!! The electrical section has all the wiring schematic's. Sounds like your main wire has come off if you have nothing at the switch. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

06-25-2016, 08:08 PM	#3
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,725	Re: Fan switch problems, Please help!! Check this thread http://67-72chevytrucks.com/vboard/s...d.php?t=658012 or search the board for "fan high speed".... there are quite a few threads about this. Maybe this will help too __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

07-17-2016, 01:36 PM	#6
Thundarr Registered User Join Date: May 2013 Location: Coppell, Texas Posts: 176	Re: Fan switch problems, Please help!! My truck had the same exact issue when I bought it. It is definitely the resistor. Once you find it under the dash, its a cheap and easy fix. Dont forget to do the heater hose shutoff in the engine bay too. It really helps cool the cab down. Lost of posts on the site about both issues. __________________ 1971 GMC C15 Sierra Grande SWB 1972 Chevy C10 Custom Deluxe LWB 2018 GMC Yukon Denali

01-16-2020, 02:26 PM	#9
toolboxchev Registered User Join Date: Jul 2015 Location: 2nd left past the stump on a dirt road. Posts: 2,629	Re: Fan switch problems, Please help!! Part of the problem to look at is the cable adjustment. Watch how hard you move those levers as they are made out of a pot metal. Look into the Never Pop Kit available in steel levers.

01-24-2020, 06:33 AM	#11
Simple10 Registered User Join Date: Apr 2019 Location: Australia Posts: 72	Re: Fan switch problems, Please help!! I haven’t taken my old resistor out as yet ... but does it look like https://rover.ebay.com/rover/0/0/0?m...2F192417359832

06-25-2016, 06:58 PM	#1
71GeneralMotorsCorp Registered User Join Date: Jul 2011 Location: Kansas Posts: 266	Fan switch problems, Please help!! Hey guys, got a quick question.. I've got a 69 Chevy c10.. Factory A/C truck. (It works too!) Since i've owned the truck, the high speed on the fan has never worked.. Driving it one day, the fan stopped blowing entirely and wouldn't turn on. So, i thought "Simple fix!!" BOY, WAS I WRONG!! I am entirely lost on what to do and what to replace.. Before everything, i checked the fuses! ALL are good and non-blown.. -First, i got a new fan switch from LMC.. plugged it in, and nothing. (NO wiring plug anymore.. P.O. changed to spade connectors..) -Secondly, Bought a fan motor relay switch and installed it.. nothing. -next, i decided to see if the fan motor itself was bad, hooked a wire from battery to terminal and it powered on just fine.. ( no noises or vibrations..) -After that I decided to go back to the plug on the fan switch and test for voltage.. (NO POWER AT ALL ON ANYTHING when switched on..) Do any of you guys know what in the world could be causing this? it's 103* outside and i'd love my A/C back!! Maybe a wiring diagram of that area would be fantastic.. __________________ "Repetition penetrates even the dullest of minds"

06-25-2016, 08:44 PM	#4
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,803	Re: Fan switch problems, Please help!! - Bad resistor.... LockDoc __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -

07-17-2016, 12:30 PM	#5
jamesmadconductor Registered User Join Date: Feb 2016 Location: Burnsville, NC Posts: 14	Re: Fan switch problems, Please help!! I stumbled across this thread after realizing that every other thread just dealt with non-functional high fan speed, but low and medium were fine. I believe that we may have the same problem; high used to be intermittent, and now I have no fan at all. I'm thinking that it's actually the resistor, as LockDoc has suggested. Have you tried this yet? I'm likely going to get into it today, if I can find the resistor. Let me know, thanks. -James- __________________ James 1949 Chevy 3800 Panel Truck 1971 Chevy C20 Cheyenne BB402 1958 Cadillac Series 62 1958 MG-A 1940 LaSalle Series 52 Coupe 1912 Ford Model T

01-24-2020, 07:09 AM	#12
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: Fan switch problems, Please help!! Should look like this. #5 in the picture. Attached Images __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

02-04-2020, 07:11 PM	#15
Simple10 Registered User Join Date: Apr 2019 Location: Australia Posts: 72	Re: Fan switch problems, Please help!! Anyone know the part number ? I can’t find a fan blower resistor on rockauto.com

02-04-2020, 07:59 PM	#16
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: Fan switch problems, Please help!! Not rock auto but here it is. https://www.classicmuscle.com/392905...hoCqIEQAvD_BwE Here it is on E bay. https://www.ebay.com/itm/173648437597 __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

02-05-2020, 12:20 AM	#17
Sheepdip Senior Member Join Date: Nov 2018 Location: Waterford California Posts: 2,630	Re: Fan switch problems, Please help!! GM #: 3929055 It was a generic switch used in that era on the A/C equipped trucks, Corvettes, Camaros etc

02-05-2020, 01:38 AM	#18
Simple10 Registered User Join Date: Apr 2019 Location: Australia Posts: 72	Re: Fan switch problems, Please help!! Thanks for the help guys appreciate it, rock suck I emailed them asking for a link because I couldn’t find it in their category they wouldn’t send me one And said we created it so you could search pretty much ....to keep the cost down.

02-20-2020, 07:22 PM	#19
Simple10 Registered User Join Date: Apr 2019 Location: Australia Posts: 72	Re: Fan switch problems, Please help!! Well the part finally turned up......now off to put it in ...... really can’t see how these fail, it’s just a piece of steal with two springs... be interesting to see the one that comes out.

02-20-2020, 10:55 PM	#22
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,710	Re: Fan switch problems, Please help!! Those are just resistors. I didn't look up-thread. Did you change out the relay? __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA



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02-20-2020, 11:39 PM	#23
Simple10 Registered User Join Date: Apr 2019 Location: Australia Posts: 72	Re: Fan switch problems, Please help!! So over this crap ... put the new Part in didn’t work so i left it in there 20 minutes later the air conditioning doesn’t work at all no more cold

02-20-2020, 11:51 PM	#25
Simple10 Registered User Join Date: Apr 2019 Location: Australia Posts: 72	Re: Fan switch problems, Please help!! Oh well got the aircon back on cold ... oops plug fell off Attached Images

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