Quest – Sunlight Supply Quest PowerDry 4000 Pro Dehumidifier User Manual

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Quest PowerDry 4000 Pro

Installation, Operation and Maintenance Instructions


Evaporator coil frosted continuously, low dehumidifying capacity.

1. Defrost thermistor loose or defective

2. Low refrigerant charge

Compressor runs with POWER button OFF.

1. Defective relay

2. Defective control board

3. Upper housing not sealed to tower

4.4 Refrigerant Charging

If the refrigerant charge is lost due to service or leak, a new charge must be accurately weighed in. If any of the old
charge is left in the system, it must be removed before weighing in the new charge. Refer to the unit nameplate for
the correct charge weight and refrigerant type.

4.5 Blower Replacement

The blower has a PSC motor and internal thermal overload protection. If defective, the complete assembly must be

1. Unplug power cord

2. Remove the front cover

3. Remove the 5 screws attaching blower inlet ring

4. Remove the 4 screws mounting impeller to underside of base plate

5. Disconnect the blower leads

6. Reassemble the new blower using the above procedure in reverse

4.6 Thermistor Replacement

The defrost thermistor probe is inserted into the coil measuring coil temperatures and reacts accordingly.

To replace thermistor:

1. Remove top cover and filter

2. Remove 5 screws holding front filter bracket

3. Remove the filter bracket and foam block underneath

4. Remove the 4 screws holding the control panel in place

5. Pull the thermistor probe from the evaporator coil, reinsert the new probe into the existing hole

6. Route the thermistor wire along the side of the heat exchanger

7. Detach and remove old thermistor wire from board

8. Attach thermistor probe wire onto board

9. Reassemble unit