A temperature compensated pressure test for refrigerant piping is critical to assure that no piping leakage exists. While nitrogen is inert, meaning it does not create an oxidative reaction, it does follow the gas laws. If the ambient temperature changes, so does the resulting pressure of nitrogen. For more detail read this article at HVAC School
Prior to testing, sweep the system from the high side backwards to the low side to carry out any air that may be in the system. A continual sweep of nitrogen with a purge/pressure testing regulator is recommended. Removal of the air before testing is critical as when the system is pressurized, if there is air in the system, the moisture in that air can fall out as liquid making it very hard to remove during evacuation.
Use the liquid line temperature and high pressure to complete the testing. Pressure the system to the maximum rated test pressure of the lowest rated component. Many times this will be the evaporator. For example it will say “Max test pressure 250 psi”
Sweep the system, take the system up to the test pressure, allow if 5 to 10 minutes to stabilize, then start the temperature compensated pressure test. When the test is started, the initial pressure, temperature, and date and time stamp will be captured. Allow the test to run for no less than 600 seconds (10 minutes) and longer if required by the manufacturer.
When the test is ended, the final temperature and pressure will be captured and measureQuick will produce a pass/fail result based upon the gas law calculations.
If you are using the Premier features of measureQuick, you can add the results of the test to the measureQuick report in place of the geolocation map.