Insufficient Cooling

TROUBLE DIAGNOSIS PROCEDURE FOR INSUFFICIENT COOLING SYMPTOM:
- Insufficient cooling




INSPECTION FLOW

Part 1 Of 2:

Part 2 Of 2:

PERFORMANCE TEST DIAGNOSES

PERFORMANCE CHART
The Nissan A/C system uses a thermal expansion valve to provide a restriction which causes a pressure change and also controls refrigerant flow through the evaporator.
The best way to diagnose a condition in the refrigerant system is to note the system pressures (shown by the manifold gauges) and the clutch cycle rate and times.
Then, compare the findings to the charts.
- The system pressures are low (compressor suction) and high (compressor discharge).
- A clutch cycle is the time the clutch is engaged plus the time it is disengaged (time on plus time off).
- Clutch cycle times are the lengths of time (in seconds) that the clutch is ON and OFF.




Test Condition
Testing must be performed as follows

Test Reading

Recirculating-to-discharge Air Temperature Table

Ambient Air Temperature-to-operating Pressure Table

TROUBLE DIAGNOSES FOR ABNORMAL PRESSURE
Whenever system's high and/or low side pressure is abnormal, diagnose using a manifold gauge. The marker above the gauge scale in the following tables indicates the standard (normal) pressure range. Since the standard (normal) pressure, however, differs from vehicle to vehicle, refer to "Ambient Air Temperature-to-operating Pressure Table".




Both High and Low-pressure Sides are Too High.




High-pressure Side is Too High and Low-pressure Side is Too Low.




High-pressure Side is Too Low and Low-pressure Side is Too High.




Both High- and Low-pressure Sides are Too Low.




Low-pressure Side Sometimes Becomes Negative.




Low-pressure Side Becomes Negative.