Automotive Air Conditioning Information Forum

No, the port is... as-is with a cap... no modifications to the pipe that I can see. Granted, this is an old setup... who knows... but doesn't look like this original pipe (from condenser to orifice tube) was ever messed with. I plan on reusing it with correct o-rings.
Original setup only had a low side "cycling" switch on the dryer along with a low side 1/4" SAE (7/16-20 UNF) fitting on the dryer for service.

Nothing else.

Granted, I'm trying to "mix" original system with R134a needs.

That is why I'm here
Bill

I didn't mean to infer that the line was modified in any way. I just wondered whether that test port was used for some other purpose, especially since it has a Schrader valve inside. It looks like it could have been used for a high-side pressure switch.

Certainly none of my R-12 service equipment will connect to it. Everything I have is 1/4" SAE Flare. Very strange.

Does another R-12 test port exist on the high side that you know of?

It's just the 3/16 high port, nothing odd about it. If you need a conversion fitting, you use something like this. If you plan to stay R12, they make a 3/16th adapter for that.

MT0142-1

I believe that is what I have on order...

Again, appreciate the feedback.

I would have sworn GM used a 3/16 hi port at that time. I have the adapter myself.

I had a 1988 GMC Suburban and still have a 1988 Mazda B2200 truck, both R-12. Each had a small 3/16" fitting for the high side port, to prevent folks from mixing up high and low. Of course GM and Toyota used one type and Ford and Mazda have the other type.

I still have both such R-12 high side adapters, and still use the one on my 1988 Mazda truck.