Author Topic: A/C Thread Sizes  (Read 968 times)

Offline ehjorten

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A/C Thread Sizes
« on: August 30, 2022, 11:53:20 AM »
What are the two different thread sizes on our A/C systems? I need to order fittings to make custom A/C hoses for my 1991 V3500 and I am not certain the size and thread pitch. I think they are 7/8"-14 and 3/4"-16, but I am not certain.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline ehjorten

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Re: A/C Thread Sizes
« Reply #1 on: August 30, 2022, 08:50:46 PM »
So I am thinking that my 1991 V3500 has metric threads on the accumulator...M27x2.0 for the connection to the low-side suction line to the compressor, and I am guessing that the discharge line to the condenser is a M20x1.5, but I am unsure because I don't have any nuts to check that this is the case.
The LS conversion Sanden SD7H15 compresser has 3/4"-16 and 7/8"-14 connections.
« Last Edit: August 30, 2022, 09:02:38 PM by ehjorten »
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline VileZambonie

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Re: A/C Thread Sizes
« Reply #2 on: September 02, 2022, 03:55:09 AM »
If you are making your own, you can order beadlock fitting assortment kits really cheap on eBay. I had a hard time finding the one at the accumulator, so I cut the hose off of the oe one, and crimped a new shell to the stock fitting. Look here too https://coldhose.com/collections/fittings
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Scott91370

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Re: A/C Thread Sizes
« Reply #3 on: September 06, 2022, 11:48:39 AM »
Here is what I found but cannot confirm it 100% (and it is for the 85).
Compressor to condenser top- #8 to #8 O-ring - DISCHARGE side of compressor
Condenser to evaporator bottom #12 O-ring to #6 O-ring - Contains Orifice Tube
Drier is mounted on the upper 3/4" fitting on the evaporator - no hose
Drier to Compressor #10 to #12 (3/4") o-ring - SUCTION side of compressor