92 LeSabre short cycling A/C compressor

[kok328]

I discovered today the I don't have cold A/C anymore (worked fine last summer). I can hear/feel the compressor short cyclying (about 5-10 seconds). I firmly believe I have lost R-12 (pressure) just slightly (an ounce or two) below specs. The last time I tried to charge my system it wouldn't take any freon and ended up wasting a can of liquid gold (R-12).

I have one can of R-12 Oil Charge that I'm hoping will bring my system up to spec enough to keep the compressor engaged.

My questions are:

Before I blow up my system and waste another can of R-12 and that is which side do I hook up to, to charge the system and where is it located on this vehicle?

Will I need to jump the low pressure switch to charge the system or should the system recover rather quickly?

Just in case I decide to measure the freon level in my system, what should the psi be on the low and high sides?

[maxwedge]

Not being a wse guy here but you need a cfc license to wtrk on a r12 system in regards to refrigerant repairs, any way short cycle is caused usually by low freon. An oil charge will not help this and may block the system, it should be evacuated, recycled, measured for what came out, checked for holding vacuum, check for leaks with a short charge and repaired, a 134 conversion may be the way to go.

[spinne1]

You risk messing up your ac system and wasting money. You need to properly diagnose the system by:

having the r12 recovered, then by having the system evacuated with a vacuum pump to see if it will hold vacuum (if not you have a leak). Then by having the system refilled and tested for specific leak locations (an electronic leak tester is the easiest and best way). Then by having the leaks fixed and parts replaced (most likely the compressor or evaporator will leak, and the accumulator MUST be replaced), then evacuated again, and then recharged. As part of this process switching to R134a is highly recommended because of the much lower cost of the refrigerant. If you do retrofit, you don't need to change your hoses unless they leak. You DO need to flush the system and add new oil (ester is best if you don't change your compressor).

You should NEVER have to jump the low pressure switch to charge the system. The compressor will kick on on its own as the refrigerant is sucked into the vacuum created by the evacuation process. It may take most of a 12 oz. can for the compressor to kick in, but it will. Also, using a container of hot water to put your can of freon in will speed up the process of charging. You cannot measure the freon in your system without removing it, and even then it is not easy. You must have expensive equipment to recover r12, and I'm not even sure if that equipment will measure the amount. You hook up to the sides that your r12 gauge set fit on. It will only go on one way. You cannot use a 134 gauge set (at least not in its default way). Your high port is on the tubing near the condensor and your low side port is on the tubing just outside the accumulator.

Again, you have a leak and therefore are likely going to waste your precious r12 if you attempt to charge your system with it. Have the system done right or do it yourself with the right tools and machinery. Cheapest way to do it yourself (if you don't have a friend who is a mechanic)? Do what I did:

Go to Buick dealer (dealers are one of the few places now that can or will recover r12) and have them recover your r12. It cost me $65. They do not even recharge r12 at this dealer anymore. They will ONLY retrofit on broken ac systems. Why? The cost of r12 is too high for them because they have to buy in a large container. They do not even have a supply on hand where I went.

Now, get an electronic leak tester from ebay (expect to pay $100 at least). Then buy a 134 gauge set. Buy a bottle of Nylog from ackits.com or acsource.com. It is vital for preventing leaks on fittings. Also get an o-ring kit and IF you need a new compressor, and IF the compressor uses sealing washers, then you need to get them before installling the new compressor. Also get a new orifice tube and a new accumulator (ackits.com is a great place to get parts). Also get a flush kit either online or from a good ac store (hard to find).

Go to Auto Zone and get a vacuum pump on their tool rental program (you buy it and get all your money back when you return it). Hook up the gauge set and the vacuum pump and run it for 20 minutes. After that, see if the system will hold the vacuum of 29 for at least 10 minutes without going down. If it goes down you have a leak. If you have a leak, open the system, flush the condensor and evaporator (but NOT the compressor or tubing with the muffler or the orifice tube), then put 8 ounces of ester oil in and reshut the system. Charge with 30 ounces of 134. Now use the leak tester to find the leak. Pay close attention to the compressor and the evaporator (yes, it is buried so do it last after all other places have checked out as NOT leaking). After leak testing replace the parts that are leaking. Now, have the system recovered again (but this time the 134, which can be done at any oil change place or garage), then repeat the process of vacuum pumping and then charging. This time it should work and you are done.