MPClark did pass the time by typing:
> I have a 97 Jeep Cherokee. Now that it's the summer I want to use my air
> conditioning. However, when I turn on the A/C, no cold air is put out
> and the compressor clutch cycles on and off, as if it were in defrost
> mode. I am sure it is set on max a/c with the fan on high, and still
> the clutch cycles on and off. I also checked the pressure of the Freon
> and that is where it's supposed to be. I was thinking it might be a
> relay of somesort that controls the clutch, maybe it is stuck it the
> defrost position? Any help would be greatly appreciated.

Without actually looking myself it sounds like your slightly low
on refrigerant. That's normal for a system as old as yours. My 93 ZJ
required a kick in the arse (3oz) back in 2000 or so and actually
might need a checkup, hasn't gotten that hot yet.

There are two sensors in the AC system. A low pressure and a high
pressure. the low one is located on the accumulator bottle, the
high one on the ac pump output.

Be careful about how you measure pressure, a correct reading depends on
outside temperature also. My guess is your at the very low edge of
the scale. Also remember to correctly get the pressure you need
to have the compressor running. That's done by jumpering the harness
to the low level switch and settign the AC on max/recirc. Both the hoses
going into the cab should be cold to the touch. If one is cold and the
other warm then your low (or very overfilled). Always trust the pressure
gauge.

If your not familiar with servicing AC systems it might be best to let
a local shop do the work. Around here it's about 90$ for an AC system
service.

For those that quote laws.. here is the EPA read
http://www.epa.gov/ozone/title6/609/recharge.html
The legality depends on the state (or country) you live in.


--
DougW