Clicking relay - The 1947 - Present Chevrolet & GMC Truck Message Board Network

krue · 11-25-2003, 11:49 PM

What would make my blower motor relay click rapidly and itermittently? It's an A/c truck and I just replaced the relay which did not fix the problem. And the blower doesn't work, although when I ran a jumper to the motor it came on. I thought the relay was bad and replaced it, but still no joy.

my new 72 · 11-26-2003, 12:27 AM

intermittent connection problem. It's either going to be in the switch, or in the wire leading from the switch to the relay, or the fuse box and the switch. That would be my guess. You can try running a jumper between the switch and the relay to check it. Just strip a small piece of insulation away at both ends of the wire to be tested and attach the jumper, them operate the switch as normal and see if the relay activates like it should. If it does, then it is a break in the wire somewhere, if not, it may be before the switch between the fuse block and it. Use a jumper the same way you did before and if it works, then it is in the wire between those two points. Just don't forget to patch the stripped test areas.

krue · 11-26-2003, 02:56 AM

I haven't had a chance to check it, but it does it with the switch unplugged. Which makes me think it's not the switch.

my new 72 · 11-26-2003, 03:06 AM

What do you mean it does it with the switch unplugged? That does not sound right. With the switch unplugged, the relay should have no power to switch the relay closed. It must be getting power from somewhere else in order to switch it closed. Is there anything else happening to coincide with the click?

krue · 11-26-2003, 05:56 AM

It only happens when the engine is running. Or I guess when the ignition is on. I need to check a wiring diagram. Does the switch apply power or supply a ground? I can't remember.

**GMCPaul** · 11-26-2003, 10:06 AM

krue a few things to check on why blower isn't functioning is look on the bottom inside of dash between the heater control area and the glove box liner for a anti-dieseling relay ( They were used on A/C trucks ) attached to it, use a jumper wire to bypass it at the connector after unplugging it if you have this relay, quite common for this relay to be bad and it will keep the blower motor from performing, also check that the ground wire is attached behind one of the screws holding the high speed relay to the blower motor and that its not frayed here or that the other end of it at the clip on end that slides onto to the dash lip portion because we have seen the relay click intermintelly when getting a poor ground and not at all without ground( I generally just run a new ground jumper to test this wire )
GMCPaul

krue · 11-26-2003, 03:14 PM

Thanks guys. It will be the weekend before I can start checking this stuff. I'll let ya'll know what I find.

krue · 11-27-2003, 08:30 AM

OK I have found that there is an intermittent ground on the green wire at the relay. It started raining on me so I haven't traced it out yet.

Huck · 11-27-2003, 10:43 AM

That ground wire is probably the #1 problem with A/C truck fan performance. Paul hit it on the head~~~. I've seen several with the problem. The grounds on our trucks are critical to so many things yet most guys seem to take them for granted--me included. Good luck~~

krue · 11-28-2003, 12:56 AM

Well, the biggest problem I have found is the engine comp. wiring harness is hacked to crap. It looks like the PO used a trailer light harness for wire, cuz everything is either green or yellow.

11-26-2003, 12:27 AM	#2
my new 72 faster, faster, faster Join Date: Dec 2001 Location: Houston ,Texas ,USA Posts: 1,354	intermittent connection problem. It's either going to be in the switch, or in the wire leading from the switch to the relay, or the fuse box and the switch. That would be my guess. You can try running a jumper between the switch and the relay to check it. Just strip a small piece of insulation away at both ends of the wire to be tested and attach the jumper, them operate the switch as normal and see if the relay activates like it should. If it does, then it is a break in the wire somewhere, if not, it may be before the switch between the fuse block and it. Use a jumper the same way you did before and if it works, then it is in the wire between those two points. Just don't forget to patch the stripped test areas. __________________ I'm going to Law School, wanna debate? It's good practice.

11-26-2003, 02:56 AM	#3
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	I haven't had a chance to check it, but it does it with the switch unplugged. Which makes me think it's not the switch. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

11-26-2003, 03:06 AM	#4
my new 72 faster, faster, faster Join Date: Dec 2001 Location: Houston ,Texas ,USA Posts: 1,354	What do you mean it does it with the switch unplugged? That does not sound right. With the switch unplugged, the relay should have no power to switch the relay closed. It must be getting power from somewhere else in order to switch it closed. Is there anything else happening to coincide with the click? __________________ I'm going to Law School, wanna debate? It's good practice.

11-26-2003, 05:56 AM	#5
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	It only happens when the engine is running. Or I guess when the ignition is on. I need to check a wiring diagram. Does the switch apply power or supply a ground? I can't remember. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

11-26-2003, 10:06 AM	#6
GMCPaul Senior Member Join Date: Mar 2000 Location: Rockville,In. USA Posts: 3,721	krue a few things to check on why blower isn't functioning is look on the bottom inside of dash between the heater control area and the glove box liner for a anti-dieseling relay ( They were used on A/C trucks ) attached to it, use a jumper wire to bypass it at the connector after unplugging it if you have this relay, quite common for this relay to be bad and it will keep the blower motor from performing, also check that the ground wire is attached behind one of the screws holding the high speed relay to the blower motor and that its not frayed here or that the other end of it at the clip on end that slides onto to the dash lip portion because we have seen the relay click intermintelly when getting a poor ground and not at all without ground( I generally just run a new ground jumper to test this wire ) GMCPaul __________________ Secure Online Catalog for-GMCPauls Truck Parts Email- GMCPAULS@GMAIL.COM

11-25-2003, 11:49 PM	#1
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Clicking relay What would make my blower motor relay click rapidly and itermittently? It's an A/c truck and I just replaced the relay which did not fix the problem. And the blower doesn't work, although when I ran a jumper to the motor it came on. I thought the relay was bad and replaced it, but still no joy. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

11-26-2003, 03:14 PM	#7
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Thanks guys. It will be the weekend before I can start checking this stuff. I'll let ya'll know what I find. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

11-27-2003, 08:30 AM	#8
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	OK I have found that there is an intermittent ground on the green wire at the relay. It started raining on me so I haven't traced it out yet. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck" Last edited by krue; 11-27-2003 at 08:36 AM.

11-27-2003, 10:43 AM	#9
Huck Senior Member Join Date: Jun 2001 Location: Shelbyville, KY Posts: 3,269	That ground wire is probably the #1 problem with A/C truck fan performance. Paul hit it on the head~~~. I've seen several with the problem. The grounds on our trucks are critical to so many things yet most guys seem to take them for granted--me included. Good luck~~

11-28-2003, 12:56 AM	#10
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Well, the biggest problem I have found is the engine comp. wiring harness is hacked to crap. It looks like the PO used a trailer light harness for wire, cuz everything is either green or yellow. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"



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