AC R-12 to R134a retrofitting

[NAJ]

Our cars do not use an orifice tube, they use an expansion valve.Usually when they fail the low side will go into a vacuum, the compressor will be engaged and no cooling, we see it on Jeeps all the time.
The controller only controls the ground side of the A/C clutch relay and and will turn the relay off under high load conditions such as high boost, wot, etc. It should not affect the A/C at idle.

[irocelectric93]

Fun fun. Im going to be doing this this weekend. I had a couple of questions before going about this. Im going to pump down my compressor....anyway of checking to see if the compressor is bad before going any further? Another thing.....the oil. I read on here to only use Ester oil....do i need to do that when i pump down the compressor or do i just pump it down change the fittings and then pump in new refrigerant? If i need to add oil do i need to get all the old oil out and if so how? Temps here are getting into the 90s now and i cant go without a/c for another summer.

[Realest]

rule of thumb
for high side operating pressures is double ambient (F) temperature plus or minus 10%.
for low side operating pressure is 10% of high side pressure plus or minus 10%

also after reviewing the thread i've noticed nobodies talked about leak detection methods.
three methods are:
- electronic sniffers
-dye and UV light
-dry nitrogen and soapy water

my opinions..electronic sniffers are CRAP...dye and UV works good, and my favorite is dry nitrogen and soapy water, its inexpensive and faster.