Is this a problem??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Machu10 · 10-20-2006, 12:33 AM

I just bought a 1971 cheyenne, and i dont know if this is a problem or not?
when you shut of the ignition, the blower motor comes on for just a second and shuts off, dont matter what the fan switch is set to, other than that blower works fine and battery is always fully charged, the PO said it has done that as long as he can remember. is this a problem? and if so, any ideas what might be causing it?

Thanks in advance

cypress TX 72 · 10-20-2006, 12:45 AM

I can tell you this - that the ignition is no way connected directly to the blower motor - BUT - the fan switch is right next to the ignition switch - so I bet if you look under there I bet that the Ign swith is loose in the ring and when you turn the key counter-clock wise ( making the bottom turn the direction of the Fan Switch) to shut it off - it connects or bumps the switch just enough to make it come on for a second or two -
Id be willing to bet a loose wire at the fan switch or loose connection is causing the connection and is being caused by the turning of the key -
There is quite a few wires connected to that speed switch in a very little space. always a problem

There is absolutly nothing else it could be - at least not at that particular time.

shake those wires and see what happens!

Lucky this is a "NO MONEY" fix

Cypress

Aarons72s · 10-20-2006, 05:00 AM

Is it an a/c truck? I almost bet it is. If so it sounds like the high speed blower relay has gone to sh!t.
Aaron

Machu10 · 10-20-2006, 11:43 AM

Aaron, yes it's an air truck.
I will look under the dash and see what i can find.

Thx for the help

woodridge · 10-20-2006, 03:04 PM

GM actually did a set up that would engage the AC compressor for just a moment when the key was turned off to help prevent dieseling. Don't know if they used this on our trucks or not.

Ackattack · 10-20-2006, 08:43 PM

While we're on this subject.

Does anyone have a wiring diagram for the A/C-heater portion?

When I re-wired my truck about 5 years ago, I ripped out all of the under dash wiring before I realized that the Painless Kit that I got didn't include the A/C stuff, so I tried to put it back together, but ever since then I don't have the "high" speed blower.

Its never really bothered me (obviously) but it would be nice to have.

Thanks
Derek

Aarons72s · 10-21-2006, 07:44 AM

I feel ya Ackattack! I cut the a/c wiring when I ripped it out of some parts trucks a few years back. Now I am going to put it back together and figured my hanes and factory survice manuals would have the diagram. Wrong! WTF! I have even told others to look in there asuming they were in there. How can they call these service manuals when they dont have all the wiring diagrams.
I would like to see the a/c wiring diagram to.
Aaron

10-20-2006, 12:33 AM	#1
Machu10 Junior Member Join Date: Oct 2006 Location: Central, Iowa Posts: 38	Is this a problem??? I just bought a 1971 cheyenne, and i dont know if this is a problem or not? when you shut of the ignition, the blower motor comes on for just a second and shuts off, dont matter what the fan switch is set to, other than that blower works fine and battery is always fully charged, the PO said it has done that as long as he can remember. is this a problem? and if so, any ideas what might be causing it? Thanks in advance __________________ 72 Cheyenne Super ShortBox, Factory Big Block, A/C PS PB. 71 Cheyenne LWB, 350, A/C, 48k Miles 70 Olds Cutlass Convert, A/C, 350 auto, 66k actual miles. 82 Corvette, Triple Black, 32k Miles, Had since new. 85 Caprice Coupe, Bottle fed 383 Stroker, 30k miles. 06 Dodge Charger Daytona, Top Banana Hemi.

10-20-2006, 12:45 AM	#2
cypress TX 72 Saving one 72 at a time!! Join Date: Sep 2005 Location: Cypress, TX Posts: 261	Re: Is this a problem??? I can tell you this - that the ignition is no way connected directly to the blower motor - BUT - the fan switch is right next to the ignition switch - so I bet if you look under there I bet that the Ign swith is loose in the ring and when you turn the key counter-clock wise ( making the bottom turn the direction of the Fan Switch) to shut it off - it connects or bumps the switch just enough to make it come on for a second or two - Id be willing to bet a loose wire at the fan switch or loose connection is causing the connection and is being caused by the turning of the key - There is quite a few wires connected to that speed switch in a very little space. always a problem There is absolutly nothing else it could be - at least not at that particular time. shake those wires and see what happens! Lucky this is a "NO MONEY" fix Cypress __________________ Born American - Living American - Will Die American Love it or leave it ! !

10-20-2006, 05:00 AM	#3
Aarons72s Registered User Join Date: Apr 2006 Location: oklahoma Posts: 10,670	Re: Is this a problem??? Is it an a/c truck? I almost bet it is. If so it sounds like the high speed blower relay has gone to sh!t. Aaron

10-20-2006, 11:43 AM	#4
Machu10 Junior Member Join Date: Oct 2006 Location: Central, Iowa Posts: 38	Re: Is this a problem??? Aaron, yes it's an air truck. I will look under the dash and see what i can find. Thx for the help __________________ 72 Cheyenne Super ShortBox, Factory Big Block, A/C PS PB. 71 Cheyenne LWB, 350, A/C, 48k Miles 70 Olds Cutlass Convert, A/C, 350 auto, 66k actual miles. 82 Corvette, Triple Black, 32k Miles, Had since new. 85 Caprice Coupe, Bottle fed 383 Stroker, 30k miles. 06 Dodge Charger Daytona, Top Banana Hemi.

10-20-2006, 03:04 PM	#5
woodridge Senior Member Join Date: Feb 2005 Location: Maynardville, Tn Posts: 3,030	Re: Is this a problem??? GM actually did a set up that would engage the AC compressor for just a moment when the key was turned off to help prevent dieseling. Don't know if they used this on our trucks or not. __________________ SEMA Network- Protect our Hobby! 71 C30 in pieces, starting to come together. Click here for A Place For Tennessee Truck Enthusiest To Meet

10-20-2006, 08:43 PM	#6
Ackattack Senior Member Join Date: Aug 2002 Location: Valley Center KS Posts: 3,525	Re: Is this a problem??? While we're on this subject. Does anyone have a wiring diagram for the A/C-heater portion? When I re-wired my truck about 5 years ago, I ripped out all of the under dash wiring before I realized that the Painless Kit that I got didn't include the A/C stuff, so I tried to put it back together, but ever since then I don't have the "high" speed blower. Its never really bothered me (obviously) but it would be nice to have. Thanks Derek __________________ Project Bruiser: 68 Pro-Touring C-10 5.3L / 4L60E Project Ironhide: 97 GMC Crew Cab 4x4 Cummins SOLD: '69 GMC 1/2T SWB TBI'd: Project No Buck Assembly Manual Index Sign up Thread!!! Factory Service Manual Index

10-21-2006, 07:44 AM	#7
Aarons72s Registered User Join Date: Apr 2006 Location: oklahoma Posts: 10,670	Re: Is this a problem??? I feel ya Ackattack! I cut the a/c wiring when I ripped it out of some parts trucks a few years back. Now I am going to put it back together and figured my hanes and factory survice manuals would have the diagram. Wrong! WTF! I have even told others to look in there asuming they were in there. How can they call these service manuals when they dont have all the wiring diagrams. I would like to see the a/c wiring diagram to. Aaron

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