outbackgeorgia

Hey Kevin,
I have both R12 and R22 gauge sets. Come on over anytime.
Dave

dr bob

R12 and R22 have the same hose connections IIRC. If the car was converted well, you'll want to use the R-134a set with the little cam-lock QD connectors.

outbackgeorgia

Oops, sorry, I have R12/22 as well as R 134 gauges
Vacuum pump also.
Dave

Kevin in Atlanta

I'll give you a ring today. You want me to bring the GT resonators and GT rear muffler for you to try out?

outbackgeorgia

Car is at Rich's shop for detailing and bolster repair. I have gauges at house, so need to do exhaust later. Just come over, I am home.

Kevin in Atlanta

UPDATE:
Dave Davies lent me his set of gauges. When I removed the high side cap I thought I heard a brief hiss. Hooked up the gauges, started the car idled at 2000 rpm and the readings were 2 and 125. Low Freon for starters. When I disconnected the high side connector a stream of foam with dye oozed out. That was unexpected. Being a newbie to AC I thought I did something wrong. Know I think the 134a adapter needs replacing.

I'm going to get a hold of a sniffer tomorrow to see if there is a leak at the 134a adapter. We used my son's black light and there seems to be dye on the underside of the hood.

The Patman

yep! that may be a bit low. Static without the car running is often around 60-70 psi, the low pressure cut off switch is around 29 psi (I think) and is on the high side of the system...sorta. running pressures should be (about) 25 and oh...say...250. the dye and foam are kinda normal...well actually a "spurt" is normal. That's why there's quick disconnect connectors on the new systems. because the r-12 connectors let freon out as you unscrew it. The foam is cavitated oil, and the dye means someone has been in looking for a leak before (though some shops put it in there as a matter of course...just in case)

the schrader valves are often a simple fix to a system leak, especially when it's a small long term leak (refill once a year for instance). just make sure they are high pressure AC system schraders. Sometimes it's nothing more than tightening them up just a bit more snug.

replacing them means system evacuation and refill. never overfill. an overfilled system has no room left for expansion and wont work any better than a low system. After it.s sucked down...evacuated, i mean, we add some stop leak. there's only one kind that works long term, and we install it even in brand new systems we just built. It's called Red Angel, and isn't cheap, but all the others just clog up the system, and this stuff works with the system and can keep it going for years without a single glitch. NEVER INSTALL IT THRU THE GAUGES. it comes in a bottle for professionals to use in an oil injector and in a can with a 134a quick disconnect for home use. Obviously, find your leak first even if it's just tightening or replacing schrader valves.

dr bob

I'll add to Pat's thoughts n this: Too often, "conversions" are done without consideration for all the rubber bits that are i contact with the oil. On the 928, there are Schreader valves at the low- and high-side ports, and then there are often-forgotten Schraeders where the pressure safety switch and pressure transducers mount. Those valves need to be changed out for R-134a-compatible valves. In that same thought, the Schraeders under the two charge ports should be completely removed when the R-134a port adapters are installed. Some adapters have little pin-pushers in them, but they aren't reliable and they do reduce flow a lot. Better to pull the old ones out completely. else risk having to clear and refill the system later when you find one isn't cutting it anymore. with old rubber seal material clogging the port.

Kevin in Atlanta

Well, there was a leak for sure - evacuated .8 pounds. Last year I am sure there was no leak. My A/C tech advised against 90 degree adapters be cause they all seem to fail.

Game plan is to remove the Freon (done). Remove drier, expansion valves and have the system flushed, then replace the 134a adapters, drier/receiver, expansion valves and every o-ring in the system before evacuating and refilling the system.

Thanks for everybody's advice and comments. I will post the results next week.

Bilal928S4

I got a kit from Roger to change all the O rings on my 91 GT even though I went back with R 12. I have another O ring kit sitting to be installed on the 90S4.

dr bob

The 90º adapter I used on the low side port is almost essential for getting the hose on for the gauge set. I think a straight one was so tall it was getting too close to the stuff above and no room for huse connection to go on. Look carefully for that fitment before you go with a straight adapter.

Kevin in Atlanta

On my S4 the 90 degree points up. The use of a straight adapter does not seem to be an issue. There is plenty room on the high side.

dr bob

On mine, the 90º adapter points up and slightly forward, and it swivels. The original R12 port was impossible to connect to with a straight adapter. Perhaps yours is better. Just tke a close look to make sure that YOUR hoses will connect OK with whatever adapter you use.

Kevin in Atlanta

When replacing the o-rings do I need to lubricate them or are they to be assembled dry?

dr bob

Lubricate them. There's a specific lubricant recommended by others here, name escapes me at the moment though. Otherwise use the same oil you'll use to fill the system.