What are the steps for checking automotive air conditioning pressure?
2 Answers
Steps for checking automotive air conditioning pressure: 1. Before inspection, first check and clean the inspection connectors of the air conditioning system and the high/low pressure connection connectors on the air conditioning pressure gauge; 2. Inspect the air conditioning pressure gauge to ensure both high and low pressure valves are properly closed and all connection connectors are securely fastened; 3. Connect the high and low pressure hoses of the air conditioning pressure gauge to the high and low pressure service diagnostic connectors via quick-connect fittings respectively - the air conditioning must be turned off during connection; 4. After connection, start the engine and turn on the air conditioning to read and record the high and low pressure values; 5. Upon completion of inspection, first turn off the air conditioning and engine before disconnecting the air conditioning pressure gauge from the service diagnostic connectors; 6. After disconnection, inspect the service diagnostic connectors on the vehicle's air conditioning refrigeration system for any potential leaks.
I've been repairing cars for many years and am quite familiar with checking car AC pressure. First, park on level ground, start the engine, turn the AC to maximum cooling, and let the compressor run for a few minutes to stabilize. Wear protective gloves and goggles—this is crucial because refrigerant leaks can harm skin and eyes. Locate the high and low-pressure ports in the engine bay: the high-pressure port is usually marked 'H' or in red near the compressor, while the low-pressure port is marked 'L' and often blue on the piping. Prepare the pressure gauge and connect it to the ports gently to avoid accidental fluid spray. After starting the AC, observe the readings: normal low pressure should be between 25 to 40 PSI, and high pressure between 150 to 250 PSI. If pressure is too low, it may indicate a refrigerant leak; if too high, the radiator or fan might be faulty. After testing, turn off the engine before disconnecting the gauge. Routine maintenance checks are helpful, especially before summer to avoid misreadings due to high temperatures. If readings are abnormal, avoid adding refrigerant yourself—take it to a professional shop for safety.
