Empowering DIYers A/C High Pressure vs. Low Pressure Port Basics

80-100 psi with the engine off is OK. The system just settles out and the pressure equalizes. When you start the engine and when the compressor turns on the 15 ... Certified A/C tech and body man here. The port behind your engine is the low pressure port. The high pressure port is under the black plastic ... LOW, LOW, Add Refrigerant. ; LOW, HIGH, Need service, possible blockage of the expansion valve or orifice tube. ; HIGH, LOW, Needs service, possibly faulty ... the low pressure port is the one near the dryer. the high pressure is the port near the compressor. ... LP & HP are Too High 3:34 Learn how to spot the issues in any AC climate system using r134A, just by reading the pressures of the system. #### A/C pressure switches are installed in the high pressure side of the system, between the compressor and the receiver/drier. The objective is to ... Start at the A/C compressor. It's attached to the front of the engine and powered by a belt and pulley. It can be at the top or down along the side of the ... The typical low pressure side PSI is between 20 and 50, so 70 is on the high side...although not likely dangerously high. If you're not getting ... After the compressor stops, pressure from the high side bleeds over to the low side via the TXV, or orifice tube. Pressure on the high side ... Low (suction)side is the larger of the two lines, high side is smaller. Suction line should be cool or cold, high side is hot.