Help Location HighSpeed Blower Relay - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sara76 · 09-26-2019, 09:29 AM

I have a 1972 C10 with Factory A/C. The high speed of the blower motor is not working. I did some reading and searching in the forums, and it seems there should be a high speed blower motor relay behind the glovebox. I removed the glovebox and all I am seeing is what I believe to be the resistor. I looked around a lot behind / under dash, and I do see two relays, both right next to the fuse panel. It I understand correctly-this would not be the factory location for the high speed blower relay, but could one of these be it??

See attached pictures-First is right behind the glovebox insert, and what I believe is the resistor, the second are 2 misc relays near fuse panel...

Thanks,

Sara

https://drive.google.com/file/d/1dqC...ew?usp=sharing

https://drive.google.com/file/d/1-SG...ew?usp=sharing

Andy4639 · 09-26-2019, 09:44 AM

Should be mounted on the right side of the box behind the glove box.
Not my pictures but they are good for showing locations.

sara76 · 09-26-2019, 10:14 AM

Andy, Thanks for the quick replay and the pictures. I have the glovebox out, and what you have pictured is definitely there on the right side, but in that not the resistor for the low and medium speeds? I was under the impression that the high speed relay was something completely separate?

Duh..I think I understand studing your picture more...The resistor is INSIDE the box...Relay is on the outside of the box....Okay so what I am seeing behind the glovebox is the highspeed relay...I guessed at as the resistor, only because when I unplugged and checked. I have no blower motor speeds....Thanks again Andy !!

Andy4639 · 09-26-2019, 11:20 AM

Yes the resister's are inside the box if you look on the left hand side you will see the wiring. If the fan motor doesn't work on the lower speeds most times it's the fan switch itself are the resisters. Take the controller out and look at the switch good. Most times it's burnt up.

If it works on lower speeds but not the high speed it's the relay.

Your welcome.

Hutch · 09-27-2019, 07:41 PM

Check the ground wire from the relay inside the cab on the firewall.
It is very short
It is located up high between the glove box and passenger side wall.

There is a short ground wire that is supposed to go one of the shroud bolts that come through the firewall
Easy test is to attach a short piece of wire while it is on high from the relay to ground.

A lot of folks do not get the ground re-attached correctly while working on the heater core

The symptoms are
Low= Low
Medium= Medium
High = Very Slow

09-26-2019, 09:29 AM	#1
sara76 Registered User Join Date: Mar 2019 Location: Pinnacle, NC Posts: 6	Help Location HighSpeed Blower Relay I have a 1972 C10 with Factory A/C. The high speed of the blower motor is not working. I did some reading and searching in the forums, and it seems there should be a high speed blower motor relay behind the glovebox. I removed the glovebox and all I am seeing is what I believe to be the resistor. I looked around a lot behind / under dash, and I do see two relays, both right next to the fuse panel. It I understand correctly-this would not be the factory location for the high speed blower relay, but could one of these be it?? See attached pictures-First is right behind the glovebox insert, and what I believe is the resistor, the second are 2 misc relays near fuse panel... Thanks, Sara https://drive.google.com/file/d/1dqC...ew?usp=sharing https://drive.google.com/file/d/1-SG...ew?usp=sharing Last edited by sara76; 09-26-2019 at 09:31 AM. Reason: Trying to attach pictures

09-26-2019, 09:44 AM	#2
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: Help Location HighSpeed Blower Relay Should be mounted on the right side of the box behind the glove box. Not my pictures but they are good for showing locations. 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.

09-26-2019, 10:14 AM	#3
sara76 Registered User Join Date: Mar 2019 Location: Pinnacle, NC Posts: 6	Re: Help Location HighSpeed Blower Relay Andy, Thanks for the quick replay and the pictures. I have the glovebox out, and what you have pictured is definitely there on the right side, but in that not the resistor for the low and medium speeds? I was under the impression that the high speed relay was something completely separate? Duh..I think I understand studing your picture more...The resistor is INSIDE the box...Relay is on the outside of the box....Okay so what I am seeing behind the glovebox is the highspeed relay...I guessed at as the resistor, only because when I unplugged and checked. I have no blower motor speeds....Thanks again Andy !! Last edited by sara76; 09-26-2019 at 10:23 AM.

09-26-2019, 11:20 AM	#4
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: Help Location HighSpeed Blower Relay Yes the resister's are inside the box if you look on the left hand side you will see the wiring. If the fan motor doesn't work on the lower speeds most times it's the fan switch itself are the resisters. Take the controller out and look at the switch good. Most times it's burnt up. If it works on lower speeds but not the high speed it's the relay. Your welcome. 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.

09-27-2019, 07:41 PM	#5
Hutch Registered User Join Date: Oct 2001 Location: Grapevine, Tx. Posts: 2,142	Re: Help Location HighSpeed Blower Relay Check the ground wire from the relay inside the cab on the firewall. It is very short It is located up high between the glove box and passenger side wall. There is a short ground wire that is supposed to go one of the shroud bolts that come through the firewall Easy test is to attach a short piece of wire while it is on high from the relay to ground. A lot of folks do not get the ground re-attached correctly while working on the heater core The symptoms are Low= Low Medium= Medium High = Very Slow __________________ John Hutchison Grapevine,Texas 68 1/2 t swb 68 Mustang 69 Jaguar 71 1/2 t swb 88 Supra CompTs6m 93 Escort GT 2005 Corolla XRS



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