A/C problem

[Suber Dave]

I have an 86 Gl-10 turbo and the air conditioning doesn't work, I flushed all the lines and no clogs, I evacuated the system and put in one 16 oz. can of R-12, the low pressure side is very high pressure (about 110 psi) and it drops slowly to about 55 psi while the compressor runs then the compressor drags and the speed sensor on the pulley notices that the clutch is slipping then shuts down the system. Is this a expansion valve problem or a compressor problem? Has anyone had to fix their A/C and what did you do? Thanks, I'm a new Subaru owner and I love it but it's hot in California.

[NorthWet]

I'm assuming that the fan belt isn't squealing its guts out and the engine isn't bogging. If squealing/bogging, compressor bearings are probably toast. If happy as a clam but pulley is not turning properly the compressor's clutch is probably shot.

 

There are a few A/C techs on the board who can tell you better, but I think those are the probablilities.

 

(EDIT: typo in first line - "fan belt is squealing" changed to "fan belt isn't squealing"

[Suber Dave]

The engine rpm is not effected and the belts do not slip or squeal on the pulleys, the compressor is what seems to drag and the clutch starts to slip (not noisy). Thanks.

[85T-REX]

It's probably time to replace the drier. I had the same problem with my RX last year. Don't run it until you do because you might pop a line. I did.

[ivantruckman]

reciever drier and tav , i think the oriface is in the thermal expantion valve, they should bolth be replaced

[McDave]

It's going to be hard to say what all you need since the clutch started slipping before you could get accurate gauge readings.

 

I don't think you have a restriction in the expansion valve otherwise the low side would have headed straight towards zero, but then I don't know how long it took to drop from 110 (static pressure) to 55 either before the clutch slipped.

 

Yes the drier should be changed anytime the system is open for more than a couple minutes, but I doubt it's actually causing a problem at this time. It will need to be changed though since it surely has absorbed enough moisture from the atmosphere to render it saturated, not to mention the possibility of it bursting and spreading desiccant throughout the system in the future.

 

So the question is, do you want to try to replace just the clutch and hope the compressor is good, or just go ahead and replace the whole compressor? When I got my Suby the decision was easy as someone had tried to change the obviously bad clutch and had broken the bolt off the front of the clutch hub. So if you decide to change just the clutch, make sure the bolt will come out before you buy the parts.

 

If you do end up changing the compressor consider switching to R134a (unless you have a stash of those old 16oz cans of R12). Since you will be changing the drier anyway now will be the time to do it. Taking into the account the price of R12 these days, if you can even find it, changing over to R134a ends up costing about the same.

 

The only thing you will need to buy extra is the adapter fittings for the gauges and Pag oil for the compressor. Of course if you don't have gauges for R134a you will need to get a shop to evacuate and recharge the system. It's important that it be charged properly (with both high and low gauges) as it's easy to overcharge with 134. In fact you will be using just 80% of the recommended amount of R12.

 

If you go this route, flush the system again with a liquid flush with the old drier and compressor removed. Backflush both the evaporator and condensor to clean any debris out of the cores and expansion valve. It's impartant to get all the old oil out of the system for compatibility purposes. Then add 5 to 6 oz of Pag oil to your compressor. Put it all together, add the adapter fittings, evacuate and recharge with R134a.

 

Note: On some adapter fittings you will need to remove the core from your original lines, others you will need to keep the core. You'll have to take a close look at how your adapters are designed to figure out which you need to do. Some just have a pin that pushes open your existing schrader valve, others have the check valve built in so you need to get your old schrader out of there.

 

That should do it. Total cost for the rebuilt compressor w/clutch, drier, freon, oil, and fittings on mine was about $350. If you get it right, the temperature out the vents should get down to about 38 degrees before the compressor cycles.