Owner's Manual

MTC-60
INSUFFICIENT COOLING
Performance Chart
EJS001B9
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
Vehicle location Indoors or in the shade (in a well-ventilated place)
Doors Closed
Door windows Open
Hood Open
TEMP. switch Max. COLD
Mode switch
(Ventilation) set
REC switch
(Recirculation) set
(blower) speed
4-speed
Engine speed 1,500 rpm
Operate the air conditioning system for 10 minutes before taking measurements.
Inside air (Recirculating air) at blower assembly inlet
Discharge air temperature at center ventilator °C (°F)
Relative humidity % Air temperature °C (°F)
50 - 60
20 (68) 6.6 - 8.3 (44 - 47)
25 (77) 10.4 - 12.4 (51 - 54)
30 (86) 14.2 - 16.7 (58 - 62)
35 (95) 18.2 - 21 (65 - 70)
40 (104) 22.0 - 25.2 (72 - 77)
60 - 70
20 (68) 8.3 - 9.8 (47 - 50)
25 (77) 12.4 - 14.4 (54 - 58)
30 (86) 16.7 - 18.9 (62 - 66)
35 (95) 21.0 - 23.6 (70 - 74)
40 (104) 25.2 - 28.1 (77 - 83)
Ambient air
High-pressure (Discharge side) kPa (kg/
cm
2
, psi)
Low-pressure (Suction side) kPa (kg/cm
2
,
psi)
Relative humidity % Air temperature °C
(°F)
50 - 70
20 (68) 961 - 1,187 (9.8 - 12.1, 139 - 172) 108 - 157 (1.1 - 1.6, 16 - 23)
25 (77) 1,295 - 1,599 (13.2 - 16.3, 186 - 228) 161.8 - 215.8 (1.65 - 2.2, 23.5 - 31.3)
30 (86) 1,285 - 1,599 (13.1 - 16.0, 186 - 228) 167 - 216 (1.7 - 2.2, 24 - 31)
35 (95) 1,520 - 1,863 (15.5 - 19.0, 220 - 279) 235 - 284 (2.4 - 2.9, 34 - 41)
40 (104) 1,765 - 2,158 (18 - 22, 256 - 313) 289.3 - 353.1 (2.95 - 3.6, 41.9 - 51.2)