99 Toyota Camry - AC is not conditioning

The AC is out of on our camry. What are the steps I need to follow to figure out why? I can’t really afford to pay the $200 it costs to figure it out from the auto center.

It does blow air and it heats it fine. A mechanic my fiance knew “fixed it” for about 3 weeks last summer. She doesn’t know what he did.

with hood open and AC on check to see if AC clutch is engaged and compressor is turning with no noise.(I conclude the belt is present and not slipping. IT my be easier if you watch the compressor and someone else works the switch. Make sure all electrical connections are hooked-up. Get a set of AC gagues and note the pressures(here is where the cost start)If pressures are way low (like low side pulling a vacuum you have lost your refridgerant sometimes you can see the leak area or the damaged part(hole in condensor) you can start charging system maybe you will see the place that is leaking. You may have to charge pratically full with some dye that is visible under UV light. Or you can get hold of a electronic leak tester and locate your leak that way. In a system with correct pressures and correct charge weight that still blows warm your looking at some kind of temp control or blend door concern.Only a very small amount of dye needs to be added but refridgerant charge must be correct to draw conclusions from pressure data