'92 MX-3 Auto Tranny
Florida

AC was ICE-cold last week. The car sat a week and now the AC blows hot. I see what appears to be a little window in the AC line near the top of the firewall. It shows nearly empty. Is this the freon window? Does the '92 use the old freon system?

 

92 does use the old freon, so retro-fitting to new freon would be a good idea. it's not too expensive either. that window is for visual check, but i've never dealt with mine, so cannot advise.

 

You can retro fit your system with R134. You must first pump down system removing what little freon you have left and then flush out the old compressor oil. The R134 retro kit comes with everything you need to retro fit. You should also pick up leak detector so you know where you are losing freon.

 

Well, found part of the problem. The compressor is not coming on. Argh! I need to see if it's a short somewhere or the compressor is bad.

 

If you lost the coolant charge, the compressor will not come on. they have a low pressure cut-off switch in the system which prevents the compressor clutch from engaging if no coolant pressure is detected.
The window you refer to is only found on an R-12 system. It will do you no good once converted to R-134a. It is used for detecting bubbles in the R-12 freon when the system is working... which currently your is not.

 

Thanks for the info! There are no good manuals on the MX-3 so I'm kind of shooting in the dark in my research. How can I tell if my coolant is low? Or do I just need to switch over to the new system and then check? I'd hate to spend that money if the compressor is bad. Man, it was ICE-COLD.

 

Hey Sally,
Since R12 is no longer available... is illegal to sell or posses, it would be a good idea for all involved to switch over in either case. But, as Vince (vlstelleto) suggests, the system must be completely purged and converted properly.
Mineral oil, what was used as a lubricant in R12's systems, is detrimental to R-134a systems. That must all be cleaned out as completely as possible and replaced with the proper lube... which I believe is a synthetic of some sort, but my knowledge on the subject is a lil' sketchy here.
Though a loop-hole in the Federal law allows you to buy R-134a, and coincidently the "conversion kit" (not install it, BTW,) I personally would have it professionally done, if I were serious about the car.

 

Yikes! I just got a quote of $350.

 

That's a GOOD price, IMO.
When my wife's Saturn had an AC problem, I was quoted $1150... more than the car itself is worth, and she already has an R-134a system in her car.
I bought the parts and fixed it in less than 3 hrs (feeling my way through it) for under $300.
I then told her that she owed me $500 and it was a bargain at that!!

 

Ok, good news is the compressor is fine, freon is full. We "jumped" the compressor and it came on. So it seems there is a short somewhere. May or may not have anything to do with the hold light periodically flashing and seatbelt light/alarm periodically coming on.