Quote Originally Posted by jick.cejoco View Post
to check compressor integrity, run the engine with the compressor clutch engaged at at around 2500 rpm, the suction pressure should drop below 28 psig. to check the high side, unplug or disable the condenser fan. the pressure should rise to around 200 psig at idle, around 230 or higher at around 2500 rpm. to retrofit, remove the compressor and drain the oil and replace with either polyol ester (POE) or polyalkylene glycol (PAG) oil. change the receiver drier to X7, change all the o-rings to the green ones (HNBR)and change the thermostatic expansion valve designed for R134a. add more airflow to the condenser by either to a bigger CFM fan or add either a pull or push fan whichever is applicable.
the problem is that it does not have an service valve on the high side. only on the low side. cycling clutch system.

the AC tech actually did what you just mentioned, but without a tachometer. he said the compressor is ok that time based on the suction reading he made.