Fan high speed - The 1947 - Present Chevrolet & GMC Truck Message Board Network

danho · 02-05-2004, 02:46 PM

The high speed on my blower motor does not work in my truck. I have heard of the fan relay going bad or a bad ground. The ground looks good so is there any way to test the relay or do I just have to buy a new one? BTW the truck is 1/2 tore apart so I don't have any battery power but stuff sure is easy to work on.

Thanks for all the help, without this board I'd be rich and have alot of free time.

Dan.

67chevemall · 02-05-2004, 02:51 PM

you could bench test the relay and see if power comes out where it should!

danho · 02-05-2004, 02:54 PM

And how would I go about doing that?
Dan.
(electrically challenged)

67chevemall · 02-05-2004, 03:13 PM

I by-passed all the hoccus poccus !
Just find the wire which makes the fan go on high and hook up a toggle switch from the fuse box. A high is all you need!

*67Fleetsidedream* · 02-05-2004, 03:20 PM

Mine never worked. I even took the relay apart and the switch. Checked all the grounds and still nothing. DO NOT hook it up direct like ^ he said. You will fry the fan motor in due time. You may want to check the coils on the passenger side. There should the a thick coil and a thin coil. The thick coil is for high speed and the thin coil is for low speed.

**Stocker** · 02-05-2004, 09:13 PM

Does your fan work on low and medium speed, just not on high? Mine did that once - it was just a bad fan speed control switch.

da-burb · 02-05-2004, 09:44 PM

first off, A/C or not? A/C has a relay, non-a/c doesn't. The coils that were mentioned are for low and medium speeds. When it is on high it bypasses the coils all together(they are called resisters I believe).

If non-a/c I would start by checking the ground strap at the blower motor. Then move to the switch on the speed lever. They are known for going bad, usually a loose rivit or bad contact inside. I usually take it apart and fix it but the parts are cheep so you can replace it too.

If it is an A/C truck then everything above applys plus you have the relay on the side of the air plenum, under the glove box. It has a ground wire that could be off or making a bad contact and they tend to go bad too.

Longhorn Man · 02-05-2004, 10:45 PM

Running power directly to the motor will do it no harm at all. That is what a relay does.

67chevemall · 02-06-2004, 10:30 AM

U bet 10 years trouble free on/off!

elk hunter · 02-07-2004, 12:10 AM

a relay controlls a steady 12 volts. the resistors bring the voltage down accordingly, hence the low and medium speed.

02-05-2004, 02:46 PM	#1
danho Pesemistic Optimist Join Date: Dec 2002 Location: Prineville, Oregon Posts: 227	Fan high speed The high speed on my blower motor does not work in my truck. I have heard of the fan relay going bad or a bad ground. The ground looks good so is there any way to test the relay or do I just have to buy a new one? BTW the truck is 1/2 tore apart so I don't have any battery power but stuff sure is easy to work on. Thanks for all the help, without this board I'd be rich and have alot of free time. Dan.

02-05-2004, 02:51 PM	#2
67chevemall Registered User Join Date: Apr 2003 Location: NB Posts: 3,367	you could bench test the relay and see if power comes out where it should! __________________ 1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD

02-05-2004, 03:13 PM	#4
67chevemall Registered User Join Date: Apr 2003 Location: NB Posts: 3,367	I by-passed all the hoccus poccus ! Just find the wire which makes the fan go on high and hook up a toggle switch from the fuse box. A high is all you need! __________________ 1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD

02-05-2004, 09:13 PM	#6
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,725	Does your fan work on low and medium speed, just not on high? Mine did that once - it was just a bad fan speed control switch. __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

02-05-2004, 09:44 PM	#7
da-burb "Ochre Ogre" Join Date: Apr 2000 Location: Springfield, MN Posts: 3,558	first off, A/C or not? A/C has a relay, non-a/c doesn't. The coils that were mentioned are for low and medium speeds. When it is on high it bypasses the coils all together(they are called resisters I believe). If non-a/c I would start by checking the ground strap at the blower motor. Then move to the switch on the speed lever. They are known for going bad, usually a loose rivit or bad contact inside. I usually take it apart and fix it but the parts are cheep so you can replace it too. If it is an A/C truck then everything above applys plus you have the relay on the side of the air plenum, under the glove box. It has a ground wire that could be off or making a bad contact and they tend to go bad too. __________________ Bowtie Truck Stop Inc. Mid-West GM Truck Restoration Parts Supplier Your Key Parts, Auto Metal Direct, Dynacorn, and Goodmark dealer. like us @ www.facebook.com/BowtieTruckStop 1971 C-10 Suburban (Ochre) 1971 K-10 Suburban (Ochre) 1972 C-10 Suburban (Ochre) 1972 K-20 Suburban (Yellow- that just aint right!) Springfield, Minnesota 56087

02-05-2004, 02:54 PM	#3
danho Pesemistic Optimist Join Date: Dec 2002 Location: Prineville, Oregon Posts: 227	And how would I go about doing that? Dan. (electrically challenged)

02-05-2004, 03:20 PM	#5
67Fleetsidedream Wiseass secured himself a BAN Join Date: Nov 2000 Location: MOON!!! Posts: 2,282	Mine never worked. I even took the relay apart and the switch. Checked all the grounds and still nothing. DO NOT hook it up direct like ^ he said. You will fry the fan motor in due time. You may want to check the coils on the passenger side. There should the a thick coil and a thin coil. The thick coil is for high speed and the thin coil is for low speed.

02-05-2004, 10:45 PM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Running power directly to the motor will do it no harm at all. That is what a relay does.

02-06-2004, 10:30 AM	#9
67chevemall Registered User Join Date: Apr 2003 Location: NB Posts: 3,367	U bet 10 years trouble free on/off! __________________ 1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD

02-07-2004, 12:10 AM	#10
elk hunter Registered User Join Date: Dec 2003 Location: oregon city, or Posts: 164	a relay controlls a steady 12 volts. the resistors bring the voltage down accordingly, hence the low and medium speed. __________________ yeah, but how's it wheel?

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