Look at it this way - what do you have to lose?

Drain the compressor, fill with the right quantity of Ester oil ($10), install a new filter/dryer ($30), connect everything up with some new o-rings ($5), then evac and recharge with R134a ($75-100).

For $150, it may work fine for a considerable time. If not, you'll be experienced and can swap out the defective parts and do it again. The only money that you will be out will be for the evac and recharge.

Well it depends on the year of your 240...

Firstly in checking the compressor:
What you see turning (to the pwr steering) is the pulley which does not turn the compressor, only the clutch bearing of the compressor. To see if the compressor itself is seized, try turning the center shaft of the pulley... you will undestand that the pulley is a seperate part of the compressor itself, try turning it by hand. This will help you determine of it is seized up, otherwise it might still be leaky but you won;t know until a lot of work later...

Nextly determine what you want to do. Let's assume that the system stopped working because of a leak that caused refriegarant to go below the minimum, 95 % chance, (the low pressure switch will disable the system). Options are:

1.. If the car is pre-91, then you have a car with the old R12 evaporator. You can fix and continue to run R12. At minimum you should flush most of the system clean, new o-rings, new dryer, new expansion valve, leak down test to determine the source of leak, repair the leak, and then vacuum and recharge. R12 is very costly these days.
If you chose to convert to cheaper R134 refrigerant, a conversion would require a new evaporator (1 day labor) in addition to all the above. You save on refriegrant now and in the future for repairs. System is known to be less performant on this car though.

2.. If the car is post-91, then you still have a car designed for R12, but that has the more efficient newer evaporator. In this case you can chost the R12 method or better convert to R134 since it is easy and cheap in maintanance.

All in all, a lot would need to be done jsut to determine the condition of the system (o-rings,connections, flush, leak test), and then you need to replace the minimum of the expansion device and the dryer (accumulator), plus the source of the leak. And only at the leak test can you determine of the compressor is leaky.

You can try one thing, you likely have a switch at the top of the dryer (pre-91) or side of the accumulator (post-91). This is the low pressure switch. Turn o nthe A/C on the dash, start the car, and then jump the two wires to this switch. Wait a few seconds to see if the relay activates. If the clutch on the compressor engages and the compressor starts to turn, then you have a low charge as explained above. Otherwise you might have an electrical fault somewhere, fuse, A/C switch, clutch wire, etc...


Hope this helps!
Greg Mustang
Montreal - Ottawa
Canada

Sounds bad, if the hoses have been disconnected for a long time.

Moisture has probably corroded the compressor parts. You can get some A/C flush and clean the crud out of the non moving parts. After it is flushed blow the coils and lines out with a good high volume air compressor. This will remove most of the flusing agent and crud.

Probably the best thing to do is convert it to r134 from the ground up. You already have to spend some $$$ anyway. Provided your condensor and evaporator are good, you will probably need a new compressor (one made for r134- that comes with the proper oil [$200-$400]). The flush will also remove to old incompatible oil. Also you will need a new in line drier ($30-90). You also may need a new expansion valve if it has been clogged by debris or is stuck.

Also check the heater valve to make sure it is not stuck on heat. Sometimes this make hot air blow out the vents, even if the ac is working.

If, by a miracle, the compressor is good you can drain the mineral oil and use ester oil, possibly. Etsre is backward compatible. PAG oil is not.

Make sure the hoses look good (if not- need replacments) and put new r134a compatible o-rings on every connection, broken or not. Make sure you pull a good vacuum on the system (rent/buy a pump or take to a shop). This is essential to boil off residual moisture and should be done immediately after puting new parts on. Don't install new parts and let it set for a day or two! Seal, evaculte and charge the system ASAP. Moisture is very bad inside of the system.

After evacuation you can charge it up and hope for no leaks.

You may be able to find rebuilt/remanufactured compressors on ebay, the internet or local A/C shops. New is also nice.

It is a big job that requires all the right parts top to bottom. One bad o-ring can spoil it all. It is not rocket science, either. Just have to be thorough, have all the parts you need and make sure all connections are tight. This would be a challenging job, but if you are up for it- no problem. This kind of inspection and overhaul would cost major dollars at a shop!

If it has been sitting open for any length of time you will have to replace the receiver drier as the desicant in it is saturated. Are you going to convert it to R-134? If it were mine to do I would start with new receiver drier, expansion valve, R-134 conversion, and flush the entire system out. Count on replacing the compressor and if you don't have to then you got off easy. The 134 conversion on the 200's requires replacing the evaporator so if you do everything on the list you will have replace everything in the system except for the compressor, condenser, and hoses. Make sure you have plenty of oil in the system too.