I've got a 93 LT1. About 3 years ago the evap drain plugged up and water leaked on the carpet. I cleaned the drain and stored the car that year. The next time I got it out the AC did not work. I did not bother with it again until this year. I discovered it was out of Freon. I decided to do a conversion to R134. I changed out the fittings and vacuumed the system. It held a vacuum for an hour. So I added about 10 oz of 134. Then started the car and started adding more. The low pressure shot up to about 65. I shut it down. When I restarted I was getting a 09 code for low Freon. The low pressure was still high I disconnected the battery to reset and added a bout another 10 oz of Freon and the low pressure shot up to over 100. I was not getting a high pressure reading, but found the reason for that was the fitting they gave me was wrog. Too tall and would not allow the gauge fitting to reach the schraeder valve to open it. I will replace that this morning. I released some of the freon to lower the pressure to about 50 on the low side. All it does now is flash the 09 code. When I reset it the fan comes on and the clutch kicks in then after a few minutes the code 09 sets again. The kit I used has the oil in it and a stop leak. I'm wondering if the orifice tube might be plugged. I also wondered if the plugged evap drain might have caused any problems. Any thoughts or suggestions greatly appreciated. Doing a road trip Wednesday in 90-100 degree heat-air would be nice

Thanks!

 

Never mind. I got it going.

 

and you accomplished this by ?

 

Never use stop leak..they should really call it..stop up...

 

I got up this morning, went out and started the car and the low pressure would cycle the compressor on at about 15 and off at about 45. So I jumped the low pressure switch and started adding freon again. It slowly started rising as I added and I began getting cool air. It was 85 and humid and it was blowing about 60 degrees at the center outlet. I hooked the switch back up and the air stayed on steady. The low pressure was around 40. I left it at that as I had to go. I still need to get the right port adapter so I can check the high pressure. Why it was acting like it did last night I do not know as I changed nothing.

I also found out too late on the stop leak. I hope I don't pay the price for that error and will not use it again in the future.

 

Glad you fixed it. Your initial Low Side readings can only be occasioned by: 1. Compressor isn't engaged so pressures are static and equalized. 2. Compressor is engaged and there's a hole in the orifice or the Accumulator/Drier has fallen apart and is plugging up the suction side or it's grossly overcharged and the high limit has failed - stand back, there will shortly be a hole in the hood.