WD Catalog 2018

911 / 1003

8-11 - -
Repair Procedure:
Check for leaks with your leak detector. If you
find a leak at a connection, tighten it then add
refrigerant as necessary. If a component or line
is leaking (defective), recover all refrigerant
from the system. Replace the defective part and
then check the compressor oil level and replace
missing oil. Evacuate and recharge with refrig-
erant, then check AC operation and perfor-
mance.
0
100
200 300
400
500
HIGH
TEMPERATURE
LOW
TEMPERATURE
150
120
90
60
30
0
10
20
30
Extremely Low Refrigerant Charge in the System
LOW SIDE LOW HIGH SIDE LOW
Tip: The sight glass is clear or shows oil streaks. The
air from vents in the cab seems warm. If there is
a low pressure or Trinary™ switch in the system
it may have shut off the compressor (clutch).
Cause: Extremely low or no refrigerant in the system.
There is a leak in the system.
Repair Procedure:
Add refrigerant to the system, at least half of the
normal full charge amount. Then perform your
leak test. As an alternative to a refrigerant, add
dry nitrogen gas to the system and then test for
leaks.
Note: It may be necessary to use a jumper wire to
bypass some types of low pressure cutout
switches to operate the compressor (clutch)
when you add refrigerant to the system.
Manifold Gauge Set Readings
Figure 8-6
Gauge reading, extremely
low refrigerant charge in
system.