Originally Posted by saumil

3. Now read the temperature (degF) corresponding to whatever low-side pressure you have from the gauge. There is s seperate dial marking for temperature corresponding to the R134a on the gauge.
4. You will need a infra-red thermometer or a thermometer that you can wrap around the low pressure hose near the low pressure valve. Measure the low pressure hose temp (degF)
5. Adjust the pressure on the low side by charging or discharging until the temp measured on the hose is between 15 to 20 degF lower than what is read from the gauge.