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: January 20102010 Versa
