new a/c compressor & R12 charge still cutting out ?

[SW SHO]

This is a typical story of either leaking system, and ill trained mechanics. Anyway, I took it in for testing, pressure, leaks etc, and was told the compressor needed replacing.

I was skeptical because I could hit the a/c clutch and it would engage but wouldn't stay engaged for more than a few minutes. Well, I know the owner of the dealership (Mazda) and his tech replaces the compressor and clutch, recharged.

Well it's blowing cold again, cycling okay for about a week, then I'm at a drive thru with the max a/c on at 60 degrees and the systems stops cycling. It wasn't really trying to cycle either, then I get on the highway and it's fine.

Is this a switch at the compressor problem? I also notice when it's cycling and I'm cruising at low speed I can hear like a spinning sound, much louder than before the replacement.

I really don't want to take it back to him to check, because I first wanted to convert to 134a and there tech on the advice of the Ford Dealer tech said "this year/model Taurus couldn't be converted" bs of course, I printed out the write up with pics from Shotimes from an 90 or 91 IIRC.

The guy is giving me a deal, all the labor and R12, new compressor for $250.00, but if it isn't done right then it's not really a deal.

Advice?

 

[dkal]

If the system was running without problems for a while then suddenly started to blow warm air in the cooling mode, it seems as though you may still have a leak in your A/C system. Causing the compressor to cycle on and off rapidly.
The low pressure switch is not allowing the compressor to run due to low refrigerant charge on the low pressure or suction side of the A/C system. The way to check this is with a A/C refrigerant manifold gauge, checking the pressures at the low and high schraeder valve fittings.
Unfortunately R12 regrigerant is hard to purchase without being a A/C technician.
There may be several other problems which may cause this such as a faulty compressor clutch. There are several posts here describing fixes for A/C problems like these on the forum.
Hope I was of little help...Good luck

 

[SW SHO]

Yeah, I'm not even sure they re-charged the system, but wouldn't you have to when you replace the compressor and clutch?

When it when warm on the max setting at idle, it wasn't really trying to cycle at all, but when I got going on the highway, it was fine and has been until today. Even at speed, it isn't over cycling to stay cool, just seems to be at idle/in town stop and go.

I've also noticed the engine temp gets a ton higher, especially at idle. I realize it's gonna do that whith the a/c actually working from the temps when it wasn't. I don't want to scoff at this guy because at $50.00/lbs for r12 and the new compressor & clutch, plus labor I'm not paying much.

I just realized this may not be in the right forum section.

 

[pjtoledo]

Those are the symptoms of the field coil inside the AC clutch going bad. OK, THe AC clutch has an electrical coil inside it. When the engine is cool everything works fine. After a few minutes the engine and AC clutch get hot. A wire inside the coil seperates and the AC stops working. Now drive down the freeway at 70-80 MPH for a few minutes. The rush of hi-speed air will cool the compressor clutch and it will start working again. Sound like yours?? You can swap out the field coil without breaking the AC lines, so no recharge is necessary. It is kind of hard to properly diagnose. You need to splice into the wires to the AC clutch and monitor current flow while it is failing.

Perry

 

[SW SHO]

That's a great diagnosis. I've not seen that on any treads before.

Update, it of course is now cycling more frequently now, so I must have massive leak if in fact they recharged it a week 1/2 ago.

If if fact it is that coil wire at the clutch, could a new compressor/clutch fail this soon? I suppose anyting is possible, but seems unlikely.