Both my truck and car have a/c but when you turn on the a/c the compressor is not engaging.

Could this be due to a low refrigerant charge?

Also out of curiosity as long as an a/c unit never leaks it will not ever need recharging....am I right? Or do even the best a/c's need recharging from time to time? If so how often?

what year car and truck?

97 S-10
84 Regal

likely low charge. apply power directly to the compressor and see if the clutch engages. you can also disconnect at the pressure switch and cross the two wires there to see if the clutch engages.

Also out of curiosity as long as an a/c unit never leaks it will not ever need recharging....am I right? Or do even the best a/c's need recharging from time to time? If so how often?
Yes, you are right but probably 75% of all the mobil A/C systems and 10% of stationary units do have leaks. (that guess may be a little high)
Refrigerant doesn't get used up or worn out, if the system gets low there is a leak.

easiest test....

First make sure the switch is getting power. Then, unplug it, bend up a paper clip, and put it in the switch-plug, this is bypassing the switch. If this doesnt turn it on, then the compressor is bad.

Most likely it is out of freon. If it was just low on freon it would do short-cycles of engaging. just find the fill-port for the freon, you'll see a "shrader valve" (same valve as your tires) just put on that and see if alil freon comes out.

Don't run the ac without a charge. Get a charging kit from the local auto parts store. Start out with one can of leak detector and sealer. Sometimes it works, sometimes not. It also has a red dye in it that you can use a black light buld to detect.

The charging kit...I've never used one before....what does this consist of? And whats a ball park price?

The kit consists of a gauge, adapter for the can and a hose to connect to the LOW side of the system along with instructions. Easy. I think the cost is less then $20?

Thanx....I found the recharge kit you speak of but it was a little higher than $20 ($37 to be exact).....the only thing is they only sell R134a.....which was great for the truck....but the Regal uses R-12....I don't think anyone sells it anymore....

Guess I could convert the Regal to R134a but I have no idea what has to be done to set it up for this.....:(

to convert, you have to take out the compressor and drain all the oil out, this can take a day or so. And it would be smart to put the system under a vacuum.

The only thing that has to change is the oil used, and you cant mix 134a oil with r12 oil, so you have to get all that r12 oil out. Mixing them will make alot of problems. Then they just make 134a fittings that go over the existing r12 fittings. Its a real easy job ive done it a 100 times.

But they do sell fake r12 you could use. The stuff we use is called "freeze 12" it works fine is about the same price as 134a.

Or you could convert, whatever you want