Expansion Valve Adjustment - Hussmann DDS Installation And Service Instructions Manual

07/02/03

EXPANSION VALVE ADJUSTMENT

Expansion valves must be adjusted to fully feed the evaporator. Before attempting to adjust
valves, make sure the evaporator is either clear of / or only lightly covered with frost, and that
the fixture is within 10 F of it's expected operating temperature.
Adjust the valve as follows:
A. Attach a probe to the suction line near the expansion valve bulb.
B. Obtain a pressure reading from the factory installed Schraeder valve. Convert
the pressure reading to a saturated temperature for the appropriate refrigerant
Temperature B minus Temperature A = Superheat
Some "hunting" of the expansion valve is normal. The valve should be adjusted so that during
the hunting the greatest difference between the two temperatures is 3 F to 5 F.
With this adjustment, during a portion of the hunting the temperature difference between the
probes will be less than 3 F (at times as low as 0 F).
Make adjustments of no more than (1/2) turn of the valve stem at a time and wait for at
least fifteen minutes before rechecking the probe temperature and making further
adjustments.
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