1993 Toyota Corolla My Air Conditioning doesn't cool

Hi,

I last year I bought this car and the A/C was not working. So I checked the pressure on low side valve and saw that there was no coolent in it. At this stage it had R12 valve. I put a r134 valve on it and filled with r134 coolent it was working fine. But now it doesn't cool at all. The compressor start but doesn't cool. I checked pressure and it is in 70psi. Suggest me what shud I do to get it working.

Regards,
Jimmy