Need help with heater problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**ScottH** · 09-05-2004, 02:17 PM

Hey guys, well finally got the chance to look at my 72 blower not working. Turns out the blower relay wasn't there, PO did some "creative" wiring on this truck. Anyway got it to work while the relay is on order. Problem I'm having is no matter where I have the controls, all the air blows out of the a/c vents. I'm trying to make sure I have heat and defrosters for the cool weather. The cables seem to be moving, but nothing out of the floor vent or the defrosters regardless of where I move the controls.

Any help or suggestions would be appreciated.

Thanks.

neonlarry · 09-05-2004, 04:54 PM

Check the flapper valve in your diverter box, I bet it is broken.

**ScottH** · 09-05-2004, 10:57 PM

Thanks Neonlarry, can u tell me how I can get to it?

neonlarry · 09-05-2004, 11:51 PM

This is a pic of diverter box under dash. The flapper valve is in the center it usually breaks along the shaft it pivots on.

**ScottH** · 09-06-2004, 12:02 PM

Thanks again, I found it and pushed it back so the air is flowing where I need it for now.

Thanks for all your help.

neonlarry · 09-06-2004, 02:44 PM

Some people have been able to repair the broken valve using some metal straps or fiberglass. Sure beats paying for a new one.

**ScottH** · 09-06-2004, 09:08 PM

I'll have to check it out better. BTW I installed a new blower motor and blow relay but the blower still doesn't work correctly on high. It does work, but at the same speed as the previous setting. Any ideas?

Thanks again.

Harold Shepard · 09-06-2004, 09:49 PM

Your switch may be bad at the high position, it is just a slide switch moving across contact points and they burn up after a time, it could be the next easy check for you.

jhow66 · 09-06-2004, 10:41 PM

When you installed the relay did you make sure the relay was getting a good ground (black wire that hooks to the relay mounting screw). To check your ground run a jumper wire from the relay to a good ground.

**ScottH** · 09-07-2004, 09:41 AM

thanks guys....I did make sure I was getting power from the switch on high position, but did not attached the ground wire. The end of off it and I was in a bit of a hurry. I'll properly mount and attach the ground and see what happens.

thanks again.

09-05-2004, 02:17 PM	#1
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,193	Need help with heater problem Hey guys, well finally got the chance to look at my 72 blower not working. Turns out the blower relay wasn't there, PO did some "creative" wiring on this truck. Anyway got it to work while the relay is on order. Problem I'm having is no matter where I have the controls, all the air blows out of the a/c vents. I'm trying to make sure I have heat and defrosters for the cool weather. The cables seem to be moving, but nothing out of the floor vent or the defrosters regardless of where I move the controls. Any help or suggestions would be appreciated. Thanks.

09-05-2004, 04:54 PM	#2
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,745	Check the flapper valve in your diverter box, I bet it is broken. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

09-05-2004, 11:51 PM	#4
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,745	This is a pic of diverter box under dash. The flapper valve is in the center it usually breaks along the shaft it pivots on. Attached Images __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

09-06-2004, 02:44 PM	#6
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,745	Some people have been able to repair the broken valve using some metal straps or fiberglass. Sure beats paying for a new one. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

09-06-2004, 10:41 PM	#9
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	When you installed the relay did you make sure the relay was getting a good ground (black wire that hooks to the relay mounting screw). To check your ground run a jumper wire from the relay to a good ground. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

09-05-2004, 10:57 PM	#3
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,193	Thanks Neonlarry, can u tell me how I can get to it?

09-06-2004, 12:02 PM	#5
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,193	Thanks again, I found it and pushed it back so the air is flowing where I need it for now. Thanks for all your help.

09-06-2004, 09:08 PM	#7
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,193	I'll have to check it out better. BTW I installed a new blower motor and blow relay but the blower still doesn't work correctly on high. It does work, but at the same speed as the previous setting. Any ideas? Thanks again.

09-06-2004, 09:49 PM	#8
Harold Shepard Registered User Join Date: May 2004 Location: Canton North Carolina Posts: 466	Your switch may be bad at the high position, it is just a slide switch moving across contact points and they burn up after a time, it could be the next easy check for you.

09-07-2004, 09:41 AM	#10
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,193	thanks guys....I did make sure I was getting power from the switch on high position, but did not attached the ground wire. The end of off it and I was in a bit of a hurry. I'll properly mount and attach the ground and see what happens. thanks again.



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