good morning guys,

with the hood opened and car running...i turned the a/c on. the interior fan engaged properly. when i looked under the hood, the compressor did dot turn on. is the unit shot or could it be the pulley/clutch? the belt and other pulleys are working properly...not sure what I should be looking at to diagnose the prob: fuses, switches, the compressor itself?

 

have you check the econ. button on the dash, that shuts the compressor off

 

hey drows, i have tried multiple combinations w/ the control unit...always ensuring that auto is on but i will check on the econ setting to make sure it's off. thank you.

 

Had the AC been working OK before hand? Reason I ask is I believe if its low on refrigerant it will not engage to protect itself. Unless a big leak appeared all of the sudden though you would have noticed a decrease in you AC performance before it leaked out enough to stop engaging

 

hey JD, the A/C hasn't worked in years...the car sat for a long time, its been on the road for a year but A/C comp hasnt engaged...i'm certain its out of coolant so I have a tank to recharge it but figured id ask for some advice prior to doing that. could the lack of coolant be the reason the compressor isn't engaging? does that affect the pulley/clutch? i made sure it was on AUTO and not ECON, unfortunately, thats not the problem.

 

Yes, if the system is low on freon, the compressor will not cycle. Really the only way to tell if the compressor is still good or not, would be to charge the system with freon and see if the compressor engages once the right amount of freon has been added.

If the compressor works after a system charge, great! Until the freon leaks out again. They now sell freon with dye built in to help locate the leaks.

 

there is a low pressure switch next the receiver/drier, if you jump that out and the compressor clutch locks up that is your problem. But you will have to pull a complete vacuum on the system to charge it correctly.

 

thanks Lord, i have a can of R-134a....will that work to test? I've heard it's not compatible with freon sytems....

 

The Discovery uses R-134a so you are good there. I think the term freon anymore gets used as a generic term for all refrigerants. I think somewhere in the early 90's it was made mandatory that all US cars sold use R134a. I cant exactly remember but one can might be enough to check if you can get the compressor to engage but it might take a little more than that

 

If the one can gets the compressor going, cool. But it may be short lived depending on the size of the leak. Once the leak has been repaired, it is strongly advised to replace the accumulator/receiver drier (the material inside will absorb moisture from the environment) then have the system vacuum tested and filled to the proper capacity.