As part of my repair/restore/upgrade of my 1987 Trans Am GTA, I need to run custom A/C lines (except for the 1 hard line) to mate up to an aftermarket Sanden compressor adapter. In doing so, I needed to know the size and style of fittings used on this car, to either have hoses made locally or order them. I hunted online for this information, but was unable to find it specifically for thirdgens (or this car), but did find some clues from a GM square body truck forum. This was enough that I could order some relatively inexpensive fittings (vs. finding out the custom hoses+fittings purchased have the wrong size fitting) online from coldhose.com to confirm size/style and they work!

The following is for my car, so please check that your car can use the same size parts/fittings as a 1987 Pontiac Firebird/Trans Am w/v8... all fittings are female o-ring style. Sizes (with part numbers from cold hose for what I tested with):

• Sanden compressor adapter (unique to my car; intend to use part #GM610 from Nostalgic A/C) - #8 (BL1302) and #10 (BL1303)
• Accumulator (Dryer) to Compressor (low/suction side - threaded connector on accumulator facing compressor) - #12 (BL1304)
• Compressor to Condenser (high/discharge side - top connector on condenser) - #8 (BL1302)
• Condenser to evaporator - N/A; I intend to use a factory hard-line from a 1990-1992 (if I can find one) as it has the orifice tube in a slightly better location for maintenance. However, that same truck form mentioned above indicates that this is a #6 fitting. YMMV.

Thought I'd share to help others.

 

Be aware that some of the AC parts on 1992 Camaros and Firebirds and maybe even late production 1991.5 cars are different than 1991 and down models. The condenser is a different style and I believe it is a parallel flow condenser and the fittings are located slightly different and I believe one of them is a different size than earlier models. Some of the other AC parts are different too.

 

Good to know. For what it’s worth, my car is a mish mash of parts. I believe the condenser I have was bought for a 1989 and is a parallel flow unit. Evaporator is for a 1991-1992 so I can run those years hard line (still need to buy one). I think the fitting sizes I shared should be generally applicable unless you’re at some strange edge cases where the parts don’t interchange at all. Hopefully it still helps someone, it for nothing else than to know where to buy some cheap fittings to test your own setup.