1994 Camry A/C

Could be:

-lack of refrig charge (low head-pressure) due leaking or just too many
years without a system check/eveac/recharge

- too much head-pressure, altho this usually come and goes as the AC system
experiences an overheat on a hot for example.

- the thermostat has thrown in the claw, refusing to tell the AC control the
car cabin temp is too high

- an electrical fault somewhere in the system, such as a break or open
circuit

-  compressor clutch has failed

You will need a manual to easily do these checks:

I'd start by checking for volts (battery=+12v0 at the compressor clutch. If
its there then the clutch is knackered. If not, then you need to check for a
fuse failure (get a manual for quick location of said fuse-box). If the
supply is OK,..next check for relay problems tho these rarely fail,..barring
that, check for probs in the control system ie thermostat failed, or a
protective shutdown is in effect etc...

Jason

One other possibility that occurred when my AC went out and the clutch
seemed like it wasn't engaging is that the compressor's shaft snapped!  I
hope this isn't the case for you because it was $$$.

Doug

It could be as simple as the dashboard switch, see if the ac is getting
12 volts