nygiantFan

evacuate system , pull vacuum for at least 30 minutes, add refrigerant, using a refrigeration scale, add proper amount of pag oil according to the sticker under the hood.. it is the only way.. it is a shame that
the sell refrigerant to the home shade tree person where a professional has to be certified. there is a lot going on with temperature charts, super heat values and the rpm of the engine and proper air flow across the condenser.. too much will back up into the compressor and blow it up.

Flamingtaco

My '93 Sable was R-12. I think Ford waited until they pretty much had to use R-134a (94 models produced in 94 would have had to have it, but those built in 93 did not). R-134a first started to appear in vehicles four or five years earlier, I believe.

Flamingtaco

If it makes you feel better, I was certified in refrigeration systems while I was serving. Gas, brine, even those propane systems you see in RV's. Then, one of my first jobs after serving was working for Sears as an HVAC assistant. Mad respect to those guys, HVAC work during the summer sucks major donkey *****.

The biggest issue for shadetree mechanics isn't figuring out the system, it's using the proper equipment. Too many will vent to atmosphere or won't purge because a cheap pump is $80, and they don't have $80.

Information about the systems is very available, it's the vehicle specific charts that you have to hunt for, but, like seen here, post in the correct forum, and the internet gods will provide.

All else being equal, most just need to top up on gas lost at the seals. That's why you'll find two brands/ten cans of gas Vs eight brands/eighty cans of gas with additives, an integrated gauge, and a manifold connector. Green/Yellow/Red gauges are stupid IMO, but the systems do have a good bit of overage built in. Mostly shadetrees that screw up their system just put it outside of optimal operating condition. I corrected a few dozen of those mistakes back when I would help peeps out for free.

The only damaged system I've come across was that 93 Sable I mentioned. The compressor shaft seal blew... boy, when those go, hope you've got your ****tin' pants on! The vehicle was under warranty, so I hadn't touched it. When I saw what the dealer billed Ford, being near the end of warranty, I pulled out the refrigeration books I trained on, and started searching the fledgling internet (it was 98 IIRC).

nygiantFan

my post wasn't meant as a slam, just wanted to post the many variables in working on an auto ac system.. as you have seen, a seal blew spewing hot refrigerant oil at high pressure, is some of the dangers..high side pressures can reach 320 psi on a hot humid day it can cause injury. i'm not posting to hurt one's integrity

D2Abbott

My diagnostic strategy is quite simple.
1) Use an identifier to be sure nobody has forced something other than R134a or something that will ruin my equipment.
2) Evacuate the system completely and bring it to a vacuum for at least 40 minutes, longer if the system has been open.
3) Add a compatible tracer dye if there isn’t any in the system already. (Many vehicles are shipped with dye pre-installed including our F150’s.)
4) Ready for this? Fill with the specified amount of refrigerant.
5) Verify high and low pressures are within specs. If they aren’t guess what? I don’t vary the amount of refrigerant, I locate the problem!
6) Figure our what brought the vehicle to me in the first place which is usually because the refrigerant leaked out. Sometimes this may take several weeks for the dye to show up, sometimes it’s minutes.

idrive

iTrader: (3)

I should have been more specific as my point was that R-12 not R-22 was used in automobiles. I am unsure of what year each OEM made the change to R-134A from R-12.

Phil48315

R-12 switched to R-134a November 14th 1994....but some manufacturers changed earlier because they were stocking up ahead of time.

Flamingtaco

Wasn't taken as such, and stating the dangers is never not acceptable in my book. Even handling the manifold can be dangerous. I always check static pressure before anything else. An overpressure system with a blockage... compressors can build some very high pressure, I've heard of injuries resulting from failing to check for equalization before pulling off the connector.

And on my wife's escape, it's the connector that's at an odd angle, under a radiator hose, two inches from the alternator mount (I think, didn't actually look at the component, just the mount). Took me so long to get it connected, gloves weren't helpful in keeping the heat at bay.

ShirBlackspots

It was mid model year 1994 where R-134a became mandatory. How do I know this? My 1994 Cavalier was produced mid-model year, and had a notice in the owners manual (and engine compartment) about the change, and it had R-134a in the system.

Napalm

Yeah I was off by a few years. I had in my head the mandatory date was 98