Takeuchi TB175W, Руководство по ремонту

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III-84 TB175W
Note: If the expansion valve tests did not cause the low
pressure gauge needle to rise and drop, and if the oth-
er procedures described did not correct the problem,
the expansion valve is defective. You must recover
all refrigerant from the system again, and replace
the expansion valve and receiver-drier. Evacuate and
recharge the system with refrigerant, then check AC
operation and performance.
Expansion Valve (TXV) Stuck Open
Tip: Air from vents in the cab is warm or only slightly cool.
Cause: The expansion valve is stuck open and/or the capillary
tube (bulb) is not making proper contact with the evap-
orator outlet tube. Liquid refrigerant may be flooding
the evaporator making it impossible for the refrigerant
to vaporize and absorb heat normally. In vehicles where
the TXV and sensing bulb are accessible, check the
capillary tube for proper mounting and contact with the
evaporator outlet tube. Then perform the following test.
If the TXV is not accessible, then proceed to Repair
Procedure .
Test: 1. Operate the AC system on it’s coldest setting for
a few minutes. Carefully spray a little nitrogen or
other cold substance, on to the capillary tube coil (bulb)
or head of the valve.
2. The low pressure (suction) side gauge needle should
now drop on the gauge. This indicates the valve has
closed and is not stuck open. Repeat the test, but
first warm the valve diaphragm with your hand.
Manifold Gauge Set Readings
Figure 8-10
Gauge reading, expansion
valve (TXV) stuck open.