AC Differences through the years - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Honest Bob · 07-18-2023, 04:47 PM

Does anyone know if there are differences in the ac system between the 73-80 and 81-87? I am converting my 75 non ac cab to ac I have everything I pulled from a 7x cab however the casing on the bottom of the evaporator core is busted up. I am wondering if I can just grab one from an 81+ square as they are easier to find with ac.

Sabaka454 · 07-18-2023, 06:44 PM

There are several differences. Be specific on what year parts and harness you are installing.

Honest Bob · 07-18-2023, 07:38 PM

Quote:

Originally Posted by Sabaka454

There are several differences. Be specific on what year parts and harness you are installing.

Thats kind of the issue. I pulled everything from a cab/front end I bought that had no vin number so I dont really know what what year its from other than being a round eye with a blade type fuse box so I can only assume 77-80.

Pontiac1976 · 07-18-2023, 11:08 PM

I can't remember for sure if the first year for blade type fuses 80. or someone changed the fuse box out of an 81-91.

Dead Parrot · 07-19-2023, 10:25 AM

Post some pictures of what you have. Unless you know the history of your donor cab, it is possible that PO got some of those parts from a different cab. One of the fun things of dealing with popular 40+ year old vehicles.

Honest Bob · 07-20-2023, 05:54 PM

Great idea! Here are the pictures of the stuff I have. The fiberglass evaporator housing is pretty damaged which is what I am trying to source, but Im not opposed to purchasing an entire 81+ setup and starting over if its going to be easier to source parts in the future. Ive run into a few headaches already trying to source a hydroboost unit with sae threads among other odd things on my 75.

Sabaka454 · 07-20-2023, 08:04 PM

You are going to have to modify the firewall and what you have there is quite rough as well as later model parts. Have you considered aftermarket AC? Like Vintage air?

Dead Parrot · 07-20-2023, 09:09 PM

It looks like some of the in-cab air tubing is missing. Factory AC routed the cold to side vents and center high vents that a heat only system didn't have. Don't know if the openings are in the metal and just covered over with plastic or will require some sheet metal work to make openings for the vents.

If you are good with fiberglass, that broken piece might be fixable but unless you are in a hurry, wait for a better part.

You also need the condenser coil(in front of radiator) and the small tube set that goes through the core support from the condenser coil to the hoses behind the core.

Don't see the metal part that holds the orifice tube.

07-18-2023, 04:47 PM	#1
Honest Bob Registered User Join Date: Jan 2017 Location: Easton PA Posts: 222	AC Differences through the years Does anyone know if there are differences in the ac system between the 73-80 and 81-87? I am converting my 75 non ac cab to ac I have everything I pulled from a 7x cab however the casing on the bottom of the evaporator core is busted up. I am wondering if I can just grab one from an 81+ square as they are easier to find with ac. __________________ 1975 GMC C35 - Junk yard survivor. 1986 Pampered Private - M1009

07-18-2023, 06:44 PM	#2
Sabaka454 Registered User Join Date: Jul 2005 Location: CT Posts: 279	Re: AC Differences through the years There are several differences. Be specific on what year parts and harness you are installing.

07-18-2023, 11:08 PM	#4
Pontiac1976 Registered User Join Date: Oct 2015 Location: Ottawa, Ontario, Canada Posts: 780	Re: AC Differences through the years I can't remember for sure if the first year for blade type fuses 80. or someone changed the fuse box out of an 81-91. __________________ 1977 REG cab Long Bed with a 1984 Front Clip, 82 305 .60 over 9.0.1 flat top pistons, 4bbl, TH350, w/84 SS-intake & cam , w/ 1977 big block rad, 1975 gear box, 1984 master w/ metric fittings top & SAE fitting @ portion block, 1975 3.42 gear open diff. Duel 77-87 Factory air cleaner, duel inlet from rad support . Down sized 9' to new 8' Steel flat bed Was a 77 454 w/308 gear. Taken out 550 lbs. up front with motor clip change.

07-19-2023, 10:25 AM	#5
Dead Parrot Registered User Join Date: Aug 2012 Location: Oklahoma City, OK Posts: 2,659	Re: AC Differences through the years Post some pictures of what you have. Unless you know the history of your donor cab, it is possible that PO got some of those parts from a different cab. One of the fun things of dealing with popular 40+ year old vehicles.

07-20-2023, 05:54 PM	#6
Honest Bob Registered User Join Date: Jan 2017 Location: Easton PA Posts: 222	Re: AC Differences through the years Great idea! Here are the pictures of the stuff I have. The fiberglass evaporator housing is pretty damaged which is what I am trying to source, but Im not opposed to purchasing an entire 81+ setup and starting over if its going to be easier to source parts in the future. Ive run into a few headaches already trying to source a hydroboost unit with sae threads among other odd things on my 75. Attached Images __________________ 1975 GMC C35 - Junk yard survivor. 1986 Pampered Private - M1009

07-20-2023, 08:04 PM	#7
Sabaka454 Registered User Join Date: Jul 2005 Location: CT Posts: 279	Re: AC Differences through the years You are going to have to modify the firewall and what you have there is quite rough as well as later model parts. Have you considered aftermarket AC? Like Vintage air?

07-20-2023, 09:09 PM	#8
Dead Parrot Registered User Join Date: Aug 2012 Location: Oklahoma City, OK Posts: 2,659	Re: AC Differences through the years It looks like some of the in-cab air tubing is missing. Factory AC routed the cold to side vents and center high vents that a heat only system didn't have. Don't know if the openings are in the metal and just covered over with plastic or will require some sheet metal work to make openings for the vents. If you are good with fiberglass, that broken piece might be fixable but unless you are in a hurry, wait for a better part. You also need the condenser coil(in front of radiator) and the small tube set that goes through the core support from the condenser coil to the hoses behind the core. Don't see the metal part that holds the orifice tube.



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