Rick's Free Auto Repair Advice

Normal Car AC manifold gauge readings

What are normal car AC manifold gauge readings?

What should my AC manifold gauges read?

Car AC manifold gauges can help you diagnose an AC issue. There’s no single reading for all temperature humidity levels and the readings will change depending on whether you perform a loaded versus unloaded performance test.

How to conduct an UNLOADED performance test

1) Perform the test in a shaded area (not in direct sunlight).

2) Front windows CLOSED

3) HVAC set to MAX RECIRCULATE MODE

4) Blower fan on HIGH

5) Hood left open

7) Run engine at 1,000 RPM for 10 mins to allow the system to stabilize.

6) Measure the ambient temperature 1-ft. in front of the grille. Do NOT use weather service temp readings.

7) Measure the air temp at the center duct.

8) AC manifold gauge readings based on center duct temperature.

car ac manifold gauge readings

Car AC manifold gauge readings

Since the windows are closed and the system is set to recirculate, you’re measuring the system’s performance with already cooled dry air passing across the evaporator.

How to perform a loaded performance test.

1) Perform the test in a shaded area (not in direct sunlight).

2) Front windows OPEN

3) HVAC set to AC (recirculation OFF)

4) Blower fan on HIGH

5) Hood left open

7) Run engine at 1,500 RPM for 10 mins to allow the system to stabilize.

6) Measure the ambient temperature 1-ft. in front of the grille. Do NOT use weather service temp readings. Obtain relative humidity readings from the weather service.

7) Measure the air temp at the center duct.

8) AC manifold gauge readings based on ambient temperature in front of vehicle, relative humidity and center duct temperature.

©, 2018 Rick Muscoplat

Posted on by Rick Muscoplat



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