A/C Compressor Questions

The clutch on my compressor for my 1993 XJ Country 4.0L Auto 2WD isn't kicking in. How do I test my relay using a meter (i.e. what posts do I contact and what should the amps/volts be?). Another question, if it turns out I need a new compressor, is there a place I can go to have mine rebuilt or should I just go ahead and get a replacement? Also, if I get a replacement what do I need to properly convert it over to R-134a. I know it takes more than those retro-fit kits so what else is needed?

To test a relay with a meter you are going to checking resistance across the coil circuit first. The resistance should be fairly high, but not open. Then apply power to the coil (jumper) and check that the drive terminals of the relay go from open to a low resistance. If this checks out then verify power to the terminal block on both supply terminals and that there is a good ground on the one side of the control circuit. after that work your way down line through the clutch coil on down to its ground following the wirring.

If the clutch is not engaging the compressor is still might be good and on most A/C set ups the clutch is replacable as a separate unit. The up side to that is you don't have to deal with emptying and recharging the R12 $$$.

Sorry, I didn't see the question about the 134a conversion at first...
There are 2 ways of going about it. Those kits will work for awhile if you take the rig in and have the system evacuated and put under a vaccum before you install the kit. Basiclly they involve an oil that is compatible between both types of refigerant and some sort of a sealer because 134a is smaller molecularly than R12 so it can leak easier out of old O rings and fittings. For a cheap fix that will last a couple of years this will work and you will get cold air for a season or two.

To do it correctly I have seen shops that will swap out the compressor, evaperator, condensor and the accumulator. This can run into big bucks but will probly work better and last a good deal longer than the cheap conversion kits.

I had one other thought about the A/C system not kicking on, on some systems if the system has no pressure in it there is a pressure switch that will cut off the compressor so it doesn't run without refigerant/ lubricant through the compressor. Check to see if there is any system pressure too.