Chapter 8- Troubleshooting & Service Procedures
3. If the low side gauge shows a drop again, the valve
is not stuck. Clean the surfaces of the evaporator
outlet and the capillary coil or bulb. Make sure the
coil or bulb is securely fastened to the evaporator
outlet and covered with insulation material. Oper-
ate the system and check performance.
Repair Procedure:
If the test did not result in proper operation of the
expansion valve, the valve is defective and must be
replaced. Recover all refrigerant from the system
and replace the expansion valve and the receiver-
drier. Evacuate and recharge the system with re-
frigerant, then check AC operation and perfor-
mance.
System High Pressure Side Restriction
Figure 8-11
Gauge reading, system high
pressure side restriction.
Tip:
Air from vents in the cab is only slightly cool. Look
for sweat or frost on high side hoses and tubing,
and frost appearing right after the point of restric-
tion. The hose or line may be cool to the touch near
the restriction.
Cause:
There could be a kink in a line, or other restriction
in the high side of the system.
8-16
