WD Catalog 2018

Chapter 8

– Troubleshooting & Service Procedures

8-16

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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 insula-

tion material. Operate the system and check per-

formance.

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 refrigerant, then check AC opera-

tion and performance.

100

200 300

400

500

HIGH

TEMPERATURE

LOW

TEMPERATURE

150

120

System High Pressure Side Restriction

LOW SIDE LOW

HIGH SIDE NORMAL-TO-HIGH

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 restriction. The hose or line may be cool to the

touch near the restriction.

Cause:

There could be a kink in a line, or other restric-

tion in the high side of the system.

Figure 8-11

Gauge reading, system high

pressure side restriction.