I have a 1988 ford F150 and the and I am trying to fix the AC on it. I changed the dryer and orifice tube filter and evacuated it and when I went to charge it I could only get about 24 lbs on the low side and the high side went to 225 and it does not cool but very little. When you shut the motor off you can hear pressure rushing through the dryer into the unit in the dash for about 10 seconds then it stops. What should I check or do. The compressor is new.