A/C Question

I'm sure this is posted elsewhere, but I'm in desperate need of help with this one.

I just recently purchased a 2003 Toyota Celica, manual 5 speed, from a private owner, and the A/C was working fine until a couple of days ago. I tried using it while parked in neutral and it sounded like either the compressor or the pump shuddered quite a bit and shut itself off, and the indicator light on the on/off button flashes on and off. My father checked the pressure on the low pressure side and it was way above where it should be. I have an appointment with my local Toyota service center to have it fixed on April 3rd, and don't want to be spending a lot of money, but really want my A/C to be working again.

Any help is much appreciated!
Thank you.