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6/28/17 3:11pm - Original Message: 'No A/C or fan in drive and neutral'
1986glht
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Newark, DE - USA

Vette(s):
1980 base auto

Joined: 5/28/2017
Posts: 8
I've been chasing a no A/C and no blower problem. With no success. Today I put the car in reverse hit the gas, and miracle of miracles freezing cold air and the blower works on all speeds!!! I put the car back in drive and nothing... I repeated it several times and it was the same result over and over again. Has anyone else had this problem? Did you find a fix? Does anyone have any suggestions? Thanks, Guy
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6/28/17 3:55pm - Reply: 'Re: No A/C or fan in drive and neutral'
1986glht
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Newark, DE - USA

Vette(s):
1980 base auto

Joined: 5/28/2017
Posts: 8
I'm certain there is a wire or wires that supply the a/c and blower motor. However without a service manual or wiring diagram to trace the appropriate wire traces I'm at a loss. Thanks, Guy
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6/28/17 3:56pm - Reply: 'Re: No A/C or fan in drive and neutral'
73shark
Standard Member
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Overland Park, KS - USA

Vette(s):
1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.

Joined: 7/9/2003
Posts: 373
The only two things electrical connected to the transmission that I can think of are the backup lights and the neutral safety switch. Since it does when switching from reverse to drive, I would suspect the backup light switch first. 

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1973 L-82 4 spd

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6/28/17 5:53pm - Reply: 'Re: No A/C or fan in drive and neutral'
stingrayjim jr Lifetime Member
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SHELBYVILLE, TN - USA

Vette(s):
1976 L48 auto

1978 L82 4speed

1994 LT1 6speed

Joined: 7/5/2002
Posts: 3934
By chance does anything else suddenly work while in reverse??....  do your gauges or dash lights work correctly?  usually funny things like this is a grounding issue, but this is kinda weird....  gotta a link for 1979 wiring, which "should" be the same, doesn't always work that way, but usually they are same/similar unless some major change happens in manufacturing.

http://repairs.willcoxcorvette.com/wp-content/uploads/2015/10/1979-wire-diagram.png




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StingrayJim
NCM Lifetime Member #1936

Stingray's '76                             StingrayJr's '78                           Lil Red '94

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6/28/17 9:59pm - Reply: 'Re: No A/C or fan in drive and neutral'
1986glht
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Newark, DE - USA

Vette(s):
1980 base auto

Joined: 5/28/2017
Posts: 8
Thanks for the reply, Jim. It'll be really helpful. Guy
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6/28/17 10:17pm - Reply: 'Re: No A/C or fan in drive and neutral'
stingrayjim jr Lifetime Member
Lifetime Member
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SHELBYVILLE, TN - USA

Vette(s):
1976 L48 auto

1978 L82 4speed

1994 LT1 6speed

Joined: 7/5/2002
Posts: 3934
welcome, keep us posted... we like a good mystery around here... hopefully not a murder mystery..... but, i know the feeling of wanting to shoot one of these things and bury it out back in a shallow grave.... but ummm, you didn't hear that from me...   ;)   

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StingrayJim
NCM Lifetime Member #1936

Stingray's '76                             StingrayJr's '78                           Lil Red '94

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6/28/17 10:44pm - Reply: 'Re: No A/C or fan in drive and neutral'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19447
You can view and/or download any of the '68-'82 wiring diagrams from my web page.

1968-1982 Corvette wiring diagrams

I would be looking for a bad engine mount that is allowing the engine to raise up somewhat in reverse, which can cause the wiring harness to move enough in some cases to either make or break contact in some circuits. The blower motor, and the A/C compressor circuits are completely separate....one should not effect the other. From the sound of it, you have a wiring issue in the harness on the passenger side of the engine compartment, or possibly in the fusebox pass-thru on the driver side, where the front engine and lighting harnesses connect to the fusebox. Sometimes just disconnecting and reconnecting this connector can fix all kinds of goofy problems like this.


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Joel Adams
C3VR Lifetime Member #56    
My Link


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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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6/29/17 10:53pm - Reply: 'Re: No A/C or fan in drive and neutral'
1986glht
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Newark, DE - USA

Vette(s):
1980 base auto

Joined: 5/28/2017
Posts: 8
Wow! Great stuff. Thanks, Guy
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