I found someone to service R-12, but it seems that my compressor is not working properly

The system still holds freon, but it doesn't blow cold air. Without knowing the Shark, he recommended replacing the compressor, receiver, and expansion valve. Does that sound correct??

Looking through the records...the compressor and receiver dryer were replaced along with flushing/evacuating the system in 2004.

The guy was only hooked up to the low side, should he have had both high and low connected for servicing freon?

 

Could have a plugged expansion valve? I cant recall, do you have rear air..if so try that..if it works, it isnt your compessor!

 

Yup have rear air, and it wasn't getting cold either.

 

It's not all that much to have the compressor rebuilt--$500 or so. Much less than buying a new one. The drier and expansion valve are standard, since if the compressor comes apart at all, all the junk blows through the system and you want all the dirt and gunk OUT.

 

Hi Brian, that's what the freon guy said. One thing I didn't understand, if the compressor had an internal failure, would it still hold freon?

 

Compressor is just a piston pump.
May hold pressure but the piston seals could be shot and not doing any
real fluid compressing.
Do you use AC often. (I know. Dumb question asking a LV guy that.)
Supposed to run AC about once a month to get the lube oil circulated.

Was in LV Christmas couple years ago and it was cold.
Especially standing outside waiting for the pirate ship show.

 

Go find another AC guy, this one is a hack or a crook or both. If he only had the low pressure side gauge hooked up he can't troubleshoot the system. He's suggesting a shotgun approach, replace everything and it's bound to fix it. BS! It could be as simple as a $1.00 o-ring that has let some of the R-12 leak out. Have someone use a sniffer, or add some dye to the R-12, or use a soap/water solution to find the leak. Then repair as necessary.

Jim Mayzurk
93 GTS 5-spd

 

Ernest,
I actaully didn't use it for several months this year, it was pretty mild in Vegas.

Jim,
I was thinking about getting another opinion

 

Another opinion would be best. System should be checked on both high and low side. If a new compressor is needed (hopefully not) give 928intl a call. I put the kit on my '86.5 and it works excellent. It came with compressor and high/low hoses and '0' rings.

 

Shotgun approach did not work so good for Cheney or his lawyer...

OK, first thing is to feel the temp of the freon going into the expansion valve and out. Should be very hot going in and very frosty going out. That should give you a sense of where you should spend you money.

If you rule out the compressor, have the shop evacuate the system. You can take it apart, flush out the lines, compressor, condenser coil with brake-clean. Have them replace the expansion valves and o-rings and drier and refill with your freon.

I did this on my 86.5 and went to 134 and the ac blew ice cubes it was so cold.

Good luck.

 

As alluded to above, the compressor can be diagnosed by checking both high & low side pressure. You definitely need another opinion!

 

Darien:

Does the AC compressor clutch engage?

It's odd that he hooked up the low side because it is by far much more difficult to get to, BUT you actually can make some assessment with either port. If the clutch is working and and the pressure on EITHER the high or the lowside stays steady at 80 or so and does not change when the clutch engages, then you have a decent charge but there is no compression going on. So, there is a chance he could be right, if that is true.

If the clutch does not engage, then you know about that relay in the controller, I imagine. It could be other things, such as a bad freeze switch or broken wire to the compressor, but these things are very easy to diagnose. If the clutch engages, then these things are ruled out.

 

It would be interesting to know what the pressure was. To fail the compressor it should have been high. With an inop. compressor other components cannot be properly diagnosed. The majority of failed expansion valves are stuck closed. The low side will be very low and sometimes pulls vacuum. This cannot be diagnosed with a failed compressor. A salesman should not work on your car.

 

You won't know if the problem is the compressor or the expansion valve without both hoses connected. Usually, by the time that a compressor has frag'd to point where there is no change in suction pressure, you've heard a lot of noises from it already.

If the low side and high side are the same pressure and don't chenge at all on engage/disengage, make sure the compressor is actually turning. There are plenty of tips on diagnosing this problem at the normal tips pages.

Find a more knowledeable "expert" to work on the car. More than a few experts have learned at the hand of other experts who have limited knowledge. Each in the chain passes along 80% of what they know, so it only takes a couple generations of this to get someone who knows less than nothing but thinks they know everything. AC is a dark science to many mechanics, since there are numbers and physics involved. And don't let anybody convince you that the AC on the 928 is at all exotic; It isn't. It's the same components used on other cars, but used on this one.

 

Again, not knowing the AC system. He connected the the port by the Drier, is that the low or high???