About six months ago I attempted to switch my A/C system from R-12 to R-134a using an off the shelf kit after my A/C stopped blowing cold. So I removed the valve stem to make sure the R-12 was all out and then I put it back after nothing came out. When I tried to put in the R-134a there was so much pressure already built up that I wasn't able to use much out of the can. So I tried to start up the A/C anyhow and the compressor clutch would only engage for about 1 sec and then disengage for 2 more secs and then engage for another second, etc... So I took all the R-134a out and I haven't touched it since.

I have been told that the reason for the compressor not working was due to air in the system.

Anyone with thoughts?

Thanks

 

you say you removed the valve stem and put it back? if you did what i think you did thats where your problem lies. remove the stem and leave it out. the new fittings for the 134 should have fittings in them. if you leave the orig. valve in and attempt to put on the new fitting the two valves will fight against themselves so it will not take a charge and your pressures will be sky high. its like clamping a garden hose at the end and expecting water to come out. also when converting r12 to 134 exspecially on a gm be sure you vaccum the system so there is no trace of r12 or oil in the system,use the correct oil for the conversion it is called ester oil. the two oils do not mix and will blow compessors if not done correctly.