I have a refrigertion unit that is not working properly. First there was a problem with the solenoid valve and then a compresser replacement. Unit is still not working. The pressures with unit runnig is 4 psi suction and 200 head, R-22. Unit has plenty of refrigerant because unit is running as the safties are all closed. The compresser does not run hot it is rather comfortable to the touch. I believe the TXV is the culprit. Testing the sensing bulb with hot and cold water should this be done with the unit on?

With the pressure reading of 4/200 it sounds like metering device is restricted, but the compressor would over heat and shut off from the low refrigerant flow coming back to it. With a restriction that bad (at 4 psi on suction) the head pressure should be a lot higher if you had a full charge(around 350 and 450) You may have two problems a restricted metering device or drier and a refrigerant leak.

There is no leak on the system for sure. All safeties are working properly

First there was a problem with the solenoid valve

If this is a pump down system I would revisit the selonoid and controler to check for proper operation and flow..