537 / 948
FATC
49
e) PRESSURE TEST
USING
MANIFOLD
GAUGES
This is a method where trouble is detected and re-
paired by using manifold gauge. The manifold gauge
indicates the refrigeration cycle high and low pres-
sure side pressures on the respective gauge.
NOTE
Make sure following conditions are fulfilled before
getting the correct gauge readings (after engine has
warmed –up
)
Engine speed
1500rpm
A/C inlet temperature
(Ambient Temperature)
30° - 35° C (86° - 95°
F)
Blower speed
High
Temperature Control
Full cold
Reference value be-
fore AC operation at
both high and low
pressure sides
5-8 kg/ cm
2
(0.5 - 0.8
MPa)
Based on the values the following conclusions can be inferred and further troubleshooting can be done.
Low Pressure side
in kg/cm
2
( M Pa)
High Pressure side
in kg/cm
2
( M Pa)
Remarks
Symptoms
Possible rea-
sons
1.5-2.5
(0.15-0.25)
14-16
(1.37-1.57)
System pressure
is normal
Normal cooling
AC system work-
ing normal
0.5-1.0
(0.05-0.1)
7-10
(0.69-0.98)
Pressure low
Insufficient cool-
ing
1. Refrigerant
quantity too
small.
2. Gas leakage.
Vacuum
5-6
(0.5-0.6)
Refrigerant fails to
circulate
No cooling expe-
rienced
Clogging of AC
cycle.
Initially 1.5-2.5
(0.15 -0.25) and
later vacuum
Initially 14-16 (
1.37-
1.57)and later
7-10
(0.69-0.98)
Moisture present
in system.
Initially works
normally but later
no cooing experi-
enced
Freezing of ex-
pansion valve due
to presence of
moisture.
4-6
(0.4-0.6)
7-10
(0.69-0.98)
Pressure on low
pressure side is
high and pressure
on high pressure
side is low.
No cooling.
Compressor De-
fective.