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Table 31 — Perfect Humidity™ Dehumidification System Subcooling Mode Service Analysis
Table 32 — Perfect Humidity Dehumidification Hot Gas Reheat Mode Service Analysis
PROBLEM CAUSE REMEDY
Subcooling Mode (Liquid Reheat)
Will Not Energize.
No power to control transformer from
evaporator-fan motor.
Check power source and evaporator-fan relay. Ensure all wire
connections are tight.
No power from control transformer to liquid
line solenoid valve.
1. Fuse open; check fuse. Ensure continuity of wiring.
2. Low-pressure switch open. Cycle unit off and allow low-
pressure switch to reset. Replace switch if it will not close.
3. Transformer bad; check transformer.
Liquid line solenoid valve will not operate. 1. Solenoid coil defective; replace.
2. Solenoid valve stuck open; replace.
Liquid line solenoid valve will not open. Valve is stuck closed; replace valve.
Low System Capacity. Low refrigerant charge or frosted evapora-
tor coil.
1. Check charge amount. Charge per Fig. 51-53.
2. Evaporator coil frosted; check and replace low-pressure
switch if necessary.
Loss of Compressor Superheat
Conditions with Subcooling/Reheat
Dehumidification Coil Energized.
Thermostatic expansion valve (TXV). 1. Check TXV bulb mounting, and secure tightly to suction line.
2. Replace TXV if stuck open or closed.
PROBLEM CAUSE REMEDY
Reheat Mode Will Not Energize. No power to control transformer from
evaporator-fan motor.
Check power source and evaporator-fan relay. Ensure all wire
connections are tight.
No power from control transformer to hot
gas line solenoid valve.
1. Fuse open; check fuse. Ensure continuity of wiring.
2. Low-pressure switch open. Cycle unit off and allow low-
pressure switch to reset. Replace switch if it will not close.
3. Transformer bad; check transformer.
Hot gas line solenoid valve will not operate. 1. Solenoid coil defective; replace.
2. Solenoid valve stuck closed; replace.
Low refrigerant charge or frosted evapora-
tor coil.
1. Check charge amount. Charge per Fig. 51-53.
2. Evaporator coil frosted; check and replace low-pressure
switch if necessary.
Loss of Compressor Superheat
Conditions with Subcooling/Reheat
Dehumidification Coil Energized.
Thermostatic expansion valve (TXV). 1. Check TXV bulb mounting, and secure tightly to suction line.
2. Replace TXV if stuck open or closed.
Excessive Superheat. Liquid line solenoid valve will not operate. Valve is stuck; replace valve.
Hot gas line solenoid valve will not close. Valve is stuck; replace valve.