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08-18-2008, 08:01 PM
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#1 |
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Account Suspended
 Join Date: Apr 2005
Location: jEFFERSON cITY mO.
Posts: 130
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need info on relay
I recently purchased a 72 swb Ac truck.Im in the process of redoing some of the wiring.Ac cabs are new to me.Next to the horn relay under the dash in another relay with a red,blue,black,andb/w wires. They run into the engine compartment about two foot long and then they were cut off.I have searched books with wiring diagrams but cant find anything showint this relay.Im almost sure it has to do with the ac.I would think maybe it was cut from the wiring hub where the main wires are joined,but dont know for sure. Any help would be greatly appreciated. Thanks for any help. edin 355
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08-19-2008, 01:11 PM
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#2 |
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Account Suspended
Join Date: Apr 2005
Location: jEFFERSON cITY mO.
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Re: need info on relay
Could someone with AC please give me some in sight on this problem.
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08-19-2008, 02:29 PM
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Registered User
Join Date: Oct 2001
Location: Grapevine, Tx.
Posts: 2,142
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Re: need info on relay
edin355
Here is a link to a wiring diagram: http://67-72chevytrucks.com/vboard/s...d.php?t=185665 From your description I do not think that the relay you are describing has anything to do with the A/C.
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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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08-19-2008, 02:42 PM
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#4 |
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Registered User
Join Date: Nov 2007
Location: Sask Canada
Posts: 1,666
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Re: need info on relay
Justin has the wiring dia here. http://67-72chevytrucks.com/vboard/s...=185856&page=5 the wire you list red,blue, black and b/w tells me that it was hooked to a after market realy like a bosh unit to run a higher curent device.
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Trueman |
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08-19-2008, 04:25 PM
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#5 |
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Registered User
Join Date: Feb 2002
Location: Vacaville, CA
Posts: 2,746
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Re: need info on relay
Is the relay simular in appearance to the horn relay? If so my best guess is that it is the TCS (transmission controlled spark) relay.
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 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 |
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08-19-2008, 07:02 PM
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#6 | |
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Registered User
Join Date: Nov 2007
Location: Sask Canada
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Re: need info on relay
Quote:
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Trueman |
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08-19-2008, 08:04 PM
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Big Block
Join Date: Mar 2005
Location: Durham, N.C.
Posts: 1,649
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Re: need info on relay
The relay is for your a/c compressor. If you are going to try to use the original a/c unit you will need to get the under hood a/c harness
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08-19-2008, 08:09 PM
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Senior Member
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
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Re: need info on relay
As mentioned it is probably an after market relay setup as the other relay it could have been is the anti-dieseling relay which was located close to the heater controls. The wires to the anti-dieseling relay were pink, dark green and orange. The relay for the AC unit should be mounted on the heater box by the passenger's side.
Jim
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1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC Last edited by JimKshortstep4x4; 08-19-2008 at 08:11 PM. Reason: Spelling |
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08-20-2008, 01:07 PM
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#9 |
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Account Suspended
Join Date: Apr 2005
Location: jEFFERSON cITY mO.
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Re: need info on relay
Thanks for the info. This has to be a stock relay.I saw one on a 72 blazer located in the same place.It goes out to the engine bay through a plug above the fuse box. The one on the blazer has been cut off at about two foot also.So because of the plug and the way the wiring was wrapped I know it must be a stock item on ac units.Someone on this board with ac must have one like this.I greatly appreciate all of the feed back so far.Still looking for someone with ac that has this relay on their truck. Thanks for any and all help.
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08-20-2008, 01:14 PM
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#10 |
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Account Suspended
Join Date: Apr 2005
Location: jEFFERSON cITY mO.
Posts: 130
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Re: need info on relay
Bigblock you said something about being used with ac compressor.If so do you know where it is wired to?I would like to make up any wiring harness that I might need.
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08-20-2008, 08:01 PM
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#11 |
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Senior Member
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
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Re: need info on relay
The relay is part of the TCS system as Neon Larry mentioned. It sounds like the system has been eliminated so you will not need the relay.
I have seen the relays on Blazers but not on trucks. Jim
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1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC |
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