Downloaded from www.Manualslib.com manuals search engine 7B-14 Air Conditioning System: Manual Type
ConditionPossible cause Correction
Manifold gauge MPa (kg/cm2) (psi)
Detail
Lo Hi
0.27 – 0.43
(2.7 – 4.3)
(38 – 61) 1.59 – 1.94
(15.9 – 19.4)
(226 – 276)
Normal condition — —
Negative pressure 0.5 – 0.6
(5 – 6)
(71.2 – 85.3) The low pressure side
reads a negative
pressure, and the high
pressure side reads an
extremely low pressure.
Presence of frost around
tubing to and from
receiver/dryer and
expansion valve. Dust particles or water
droplets are either
stuck or frozen inside
expansion valve,
preventing the
refrigerant from
flowing.Clean expansion
valve.
Replace it if it cannot
be cleaned.
Replace receiver/
dryer.
Evacuate the A/C
system and recharge
with fresh refrigerant.
Normal:
0.27 – 0.43
(2.7 – 4.3)
(38 – 61)
↑ ↓
Abnormal:
Negative pressure Normal:
1.59 – 1.94
(15.9 – 19.4)
(226 – 276)
↑
↓
Abnormal:
0.7 – 1.0
(7 – 10)
(100 – 142) During A/C operation, the
low pressure side
sometimes indicates
negative pressure, and
sometimes normal
pressure. Also high
pressure side reading
fluctuates between the
abnormal and normal
pressure.
Expansion valve is
frozen due to
moisture in the
system, and
temporarily shuts off
the refrigeration cycle.
Replace expansion
valve.
Replace receiver/
dryer.
Evacuate A/C system
and recharge with
fresh refrigerant.
0.05 – 0.15
(0.5 – 1.5)
(4.2 – 21.3) 0.7 – 1.0
(7 – 10)
(100 – 142) Both low and high
pressure sides indicate
low readings.
Output air is slightly cold.
Insufficient refrigerant
in system
(Refrigerant leaking).Using leak detector,
check for leaks and
repair as necessary.
Recharge refrigerant
to a specified amount.
If the pressure reading
is almost 0 when the
manifold gauges are
attached, check for
any leaks, repair
them, and evacuate
the system.
0.4 – 0.6
(4 – 6)
(56.9 – 85.3) Pressure on low pressure
side is high.
Pressure on high
pressure side is low.
Both pressure becoming
equal right after A/C is
turned OFF.
Internal leak in
compressor.
Inspect compressor
and repair or replace
as necessary.
