Auto Air Conditioner

[gary]

The Air Conditioner in my 1992 Miata is getting weak. Car has 145K miles on it and the paint is peeling off but it's PAID FOR and gets 30MPG.

What issues will I have getting it fixed given it's probably using the bad freon?

[Pappy]

Unless you can find someone other than a licensed professional that has R-12 that you trust, you are stuck with converting to R-34. It doesn't work as well in systems designed for R-12 but there are addditives and other 'stuff' that is supposed to boost the performance.

[rjwaldren]

Freon doesn't go bad, it get's dirty... That said, depending on how the system is failing it may not be possible to put back what they take out while repairing it. It's probably R-12 so it's going to be expensive and difficult to find anyone who will even touch it (R-12 was phased out not long after the car was made). It may require a retrofit to R134A or perhaps one of the R12 drop in alternatives.

Regardless of how they fix it, I wouldn't be surprised to hear prices reaching the $500 range, with parts/labor. I'm more or less thinking out loud based on what I found about 8 years ago, I could be way off (probably too high).

[LinuxRandal]

I believe it has come back down, based on no more available R12 (they can't gouge for the conversions).

I bought a new compressor off of Ebay, for my truck, since my cost (was working at a garage at the time), was close to $300 for my compressor. I priced one the other day as my compressors clutch is going bad (one problem with buying parts online), and NEW it is down to $169.

That said, one of the mechanics converted his, and when he did, they had an adjustible oriface tube, that was supposed to make a difference. He seemed to think it did, as compared to a similar truck he had access to, and did.

If your compressor is OK, then it should be less, I would think. If it has a leak, then your talking a whole nother ball game.

[gary]

It still cools but barely - so I'm understanding I don't have to replace the compressor if it's OK.
I should probably take it in and let them capture the remainder of the R12 in the system - don't want to melt the north pole LOL. Santa would be mad!

[mpc]

Pop the hood and look for a couple things:
1: somewhere on the underside of the hood or along the structure near the radiator will be a sticker stating the refrigerant type in the system - either R-12 or R-134a. Some manufacturers converted to R-134a fairly quickly... maybe you're one of the lucky ones.

2: follow the hoses from the a/c compressor. (it's the roundish silverish thing driven by the V-belt/serpentine belt that has a funky looking belt pully... it won't be hollow - it'll have a metal plate covering it, that's part of the "clutch" assembly). Look at the hoses, especially the connections. Any wet/greasy spots? R-12 systems get wet/greasy spots at the leaks; R-134a leaks are harder to eyeball.

3: most a/c hoses have crimped-on metal ends - a round sleeve passes over the hose and then gets squeezed in several places; inside the hose is a ribbed metal pipe. The "squeezes" should line up with the valleys of the ribs to make the rubber hose take a /\/\/\/\/\ shape. When the rubber part of the hose gets old & hard, it doesn't seal too well. Grab each hose a couple inches away from the metal sleeve and flex it while listening for sounds of leakage... if you can make it leak then the hose needs to be replaced or rebuilt. A/C shops cut off the old metal shells, preserving the metal pipe inside... new rubber hose plus new shells plus a new crimp job and you've got a rebuilt hose assembly.

4: start up the car and run the a/c on max for a couple minutes. CAREFULLY feel the temps of the two hoses on the compressor. The skinnier one should be pretty hot (compressed refrigerant); the other will be chilly. A system low on refrigerant will have a warm, not hot, output pipe. If you have a hot output pipe... and the other is warm (ambient temp) or hotter, then the expansive valve or orifice tube (whichever style your car uses) inside the evaporator assembly (the radiator box that actually chills the air) is plugged or is totally open. That's a more involved repair, especially if getting to the evaporator assembly requires disassembling a lot of dash stuff.

O-rings are used at the connections on most a/c systems these days. They're quick/easy to replace for the shops... most of the $$ in a/c repair is for refrigerant and technician time to recharge the system.

Most cars pass the chilled air through the same ducts that feed the heater... if the mechanism that controls the heater core is flakey then you'll be heating the air conditioned air - the a/c is fine, the problem is elsewhere. With the a/c off but the fan running (i.e. fan in vent mode) see if the air is outside air temp or hotter... if it's hotter, your heater controls are stuck ON.

mpc