MTC-50
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Testing must be performed as follows:
TEST READING
Recirculating-to-discharge Air Temperature Table
Ambient Air Temperature-to-operating Pressure Table
*1: With blower control dial in the "1" position
*2: With blower control dial in the "4" position.
TROUBLE DIAGNOSIS FOR ABNORMAL PRESSURE
Whenever system’s high and/or low side pressure(s) is/are abnormal, diagnose using a manifold gauge. The
marker above the gauge scale in the following tables indicates the standard (usual) pressure range. Since the
standard (usual) pressure, however, differs from vehicle to vehicle, refer to above table (Ambient air tempera-
ture-to-operating pressure table).
Vehicle condition Indoors or in the shade (in a well-ventilated place)
Doors Closed
Door window Open
Hood Open
TEMP. Max. COLD
Mode control dial (Ventilation) set
Intake door lever (Recirculation) set
Blower speed Max. speed set
Engine speed Idle speed
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)
7.2 - 9.1 (45 - 48)
25 (77) 11.4 - 13.8 (53 - 57)
30 (86) 15.5 - 18.4 (60 - 65)
35 (95) 20.3 - 23.7 (69 - 75)
60 - 70 20 (68)
9.1 - 10.9 (48 - 52)
25 (77) 13.8 - 16.2 (57 - 61)
30 (86) 18.4 - 21.3 (65 - 70)
35 (95) 23.7 - 27.1 (75 - 81)
Ambient air
High-pressure (Discharge side)
kPa (bar, kg/cm
2 , psi) Low-pressure (Suction side)
kPa (bar, kg/cm2 , psi)
Relative humidity
% Air temperature
°C ( °F)
50 - 70 20 (68)
843 - 1,036 *1
(11.08 - 13.63, 8.6 - 10.6, 122 - 150) 159.0 - 194.0
(1.59 - 1.94, 1.62 - 1.98, 23.1 - 28.1)
25 (77) 1,094 - 1,338 *1
(10.94 - 13.38, 11.2 - 13.6, 159 - 194) 196.3 - 240.0
(1.96 - 2.40, 2.00 - 2.45, 28.5 - 34.8)
30 (86) 1,298 - 1,590 *1
(12.98 - 15.90, 13.2 - 16.2, 188 - 231) 248.0 - 302.7
(2.48 - 3.03, 2.53 - 3.09, 36.0 - 43.9)
35 (95) 1,383 - 1,688 *2
(13.83 - 16.88, 14.1 - 17.2, 201 - 245) 308.8 - 377.4
(3.09 - 3.77, 3.15 - 3.85, 44.8 - 54.7)
40 (104) 1,628 - 1,988 *2
(16.28 - 19.88, 16.6 - 20.3, 236 - 288) 377.4 - 461.2
(3.77 - 4.61, 3.85 - 4.70, 54.7 - 66.8)
Revision: May 2010 2011 Versa
MTC-52
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Both High- and Low-pressure Sides are Too Low
Low-pressure Side Sometimes Becomes Negative
Low-pressure Side Becomes Negative
Gauge indication Refrigerant cycle Probable causeCorrective action
Both high- and low-pressure
sides are too low. • There is a big temperature dif-
ference between liquid tank
outlet and inlet. Outlet tem-
perature is extremely low.
• Liquid tank inlet and expan- sion valve are frosted. Liquid tank inside is slightly
clogged.
• Replace liquid tank.
• Check oil for contamination.
• Temperature of expansion valve inlet is extremely low as
compared with areas near liq-
uid tank.
• Expansion valve inlet may be
frosted.
• Temperature difference oc- curs somewhere in high-pres-
sure side. High-pressure pipe located be-
tween liquid tank and expansion
valve is clogged.
• Check and repair malfunc-
tioning parts.
• Check oil for contamination.
Expansion valve and liquid tank
are warm or only cool when
touched. Low refrigerant charge.
↓
Leaking fittings or componentsCheck refrigerant for leaks.
Refer to
MTC-92, "
Checking of
Refrigerant Leaks" .
There is a big temperature dif-
ference between expansion
valve inlet and outlet while the
valve itself is frosted. Expansion valve closes a little
compared with the specification.
↓
1. Improper expansion valve
adjustment.
2. Malfunctioning expansion valve.
3. Outlet and inlet may be clogged. • Remove foreign particles by
using compressed air.
• Replace expansion valve.
• Check oil for contamination.
An area of the low-pressure pipe
is colder than areas near the
evaporator outlet. Low-pressure pipe is clogged or
crushed.• Check and repair malfunc-
tioning parts.
• Check oil for contamination.
Air flow volume is not enough or
is too low. Evaporator is frozen.• Check thermo control amp.
Refer to MTC-38, "
Magnet
Clutch Circuit (If Equipped)"
.
• Replace compressor.
• Repair evaporator fins.
• Replace evaporator.
•Refer to MTC-34, "
Front
Blower Motor Circuit" .
AC353A
Gauge indication Refrigerant cycleProbable causeCorrective action
Low-pressure side sometimes be-
comes negative. • Air conditioning system does
not function and does not cy-
clically cool the compart-
ment air.
• The system constantly func-
tions for a certain period of
time after compressor is
stopped and restarted. Refrigerant does not discharge
cyclically.
↓
Moisture is frozen at expan-
sion valve outlet and inlet.
↓
Water is mixed with refrigerant.
• Drain water from refrigerant
or replace refrigerant.
• Replace liquid tank.
AC354A
Revision: May 2010 2011 Versa
