What should my AC pressure be when off?

That is normal when the compressor is off. When you turn it on, watch the pressures. The low side will drop to 25-40psi, and the high side will go to around 200psi.

What should my AC pressure gauge reading be?

This is the second part of a series on AC pressure gauge readings. If you missed part I, start here. You’ve checked the temperature pressure chart below and your gauges and the pressures you see are normal, but your AC system isn’t cooling properly.

What does a manifold gauge on an AC mean?

A manifold gauge set measures refrigerant pressures inside of an air conditioning system. An automotive air conditioner has a high and low side, divided by a metering device and the A/C compressor.

What should my AC pressure be with the compressor off?

That’s normal with the compressor off. Then watch the pressures when you turn it on. The low side will drop to 25-40psi, and high side should go to around 150-200psi.

Why does my AC pressure gauge not equalize?

1) You haven’t waited long enough for the pressures to equalize, or 2) The orifice tube, expansion valve, compressor reed valves or stuck or there’s a severe restriction somewhere in the system that’s preventing the pressure from equalizing. In that case, you must fix that problem first. Troubleshooting incorrect static pressures

A manifold gauge set measures refrigerant pressures inside of an air conditioning system. An automotive air conditioner has a high and low side, divided by a metering device and the A/C compressor.

What should the temperature be with the AC on?

With the engine running and AC on and an ambient temperature of 75°F, a typical normal reading is around 35/150 Here the gauges show lower than normal pressures on both the high and low sides. This is an indication of a low charge Ambient temp is the outside atmospheric temperature.