Troubleshooting With Manifold Pressure Gauges

Read the manifold gauge pressure with the following established conditions:
1. Temperature at the air inlet is 30-35°C (86-95°F).
2. Engine running at 2000 rpm.
3. Blower speed set at HIGH.
4. Temperature control lever set at COOL.

NOTE: Gauge indications may vary slightly due to ambient temperature conditions.




Normally functioning refrigeration system gauge reading:

Low pressure side: 1.5-2.0 kg/cm2 (21-28 psi, 147-196 kPa)
High pressure side: 14.5-15.0 kg/cm2 (206-213 psi, 1,422-1,471 kPa)







Moisture Present In Refrigeration System

Condition: Periodically cools and then fails to cool.







Insufficient Refrigerant

Condition: Insufficient cooling.







Poor Circulation Of Refrigerant

Condition: Insufficient cooling.







Refrigerant Overcharge Or Insufficient Cooling Of Condenser

Condition: Does not cool sufficiently.







Expansion Valve Improperly Mounted Or Heat Sensing Tube Defective (Opens Too Wide)

Condition: Insufficient cooling.







Air Present In Refrigeration System

Condition: Does not cool sufficiently.

NOTE:These gauge indications are shown when the refrigeration system has been opened and the refrigerant charged without vacuum purging.







Refrigerant Does Not Circulate

Condition: Does not cool (Cools from time to time in some cases).







Insufficient Compression

Condition: Does not cool.