Manifold Gauge Set: Notes

A manifold gauge set is used to determine the system's high-side and low-side pressures, correct refrigerant charge, and operating efficiency. High (discharge) and low (suction) pressures must be compared to determine system operation. Manifold gauge sets for the 2 refrigerant types are basically the same except for fittings at ends of hoses. Fittings are different to ensure connection only to appropriate refrigerant system.

Service hoses on gauge set should have a manual turn wheel or automatic back-flow valves at service port connector ends. This will prevent refrigerant from being released into the atmosphere.

1. Low-Side Gauge & Hose
   
   Low-side gauge, which may have a Blue identifying feature, is used to measure low-side (suction) pressure. Low-side gauge is also called a compound gauge because it can measure pressure and vacuum. Pressure scale ranges from 0 to 150 psi; vacuum scale ranges from 0 to 30 in. Hg. Low-side hose is Blue, with a Black stripe.
2. High-Side Gauge & Hose
   
   High-side gauge, which may have a Red identifying feature, is used to measure high-side (discharge) pressure. Gauge scale ranges from 0 to 500 psi. High-side hose is Red, with a Black stripe.
3. Center Manifold Hose
   
   Center manifold hose is either Yellow or White with a Black stripe. Center hose is used to recover, evacuate and charge refrigerant system. When low-side or high-side pressure valves are opened, refrigerant will escape through the charge hose.