Honeywell DH90A1007 Installation Guide - Page 11

For HVAC Installer Only • Installation Guide Fan does not run with ventilation activated. Compressor runs briefly but cycles on & off with humidity control turned to ON. 1. Loose connection in fan circuit. 2. Obstruction prevents fan rotation. 3. Defective fan. 4. Defective fan relay. 5. Defective fan capacitor. Evaporator coil frosted continuously, low dehumidifying capacity. 1. Defrost thermostat loose or defective. 2. Low refrigerant charge. 3. Dirty air filter(s) or airflow restricted. Unit not providing ventilation. 1. Check control wire connections (check connections at fresh air damper also). 2. Defective fresh air damper. 3. Dirty air intake. Clean outside intake hood. Unit removes some water, but not as much as expected. 1. Air temperature and/or humidity have dropped. 2. Humidity meter and or thermometer used are out of calibration. 3. Unit has entered defrost cycle. 4. Air filter dirty. 5. Defective defrost thermostat. 6. Low refrigerant charge. 7. Air leak such as loose cover or ducting leaks. 8. Defective compressor. 9. Restrictive ducting. 10. Optional Condensate Pump Safety Switch open. Unit Test to determine problem: 1. Detach field control wiring connections from main unit. 2. Connect the yellow and green pigtails from the main unit together; only the impeller fan should run. Disconnect the wires. 3. Connect the yellow and blue pigtails from the main unit together; the compressor and impeller fan should run. 4. If these tests work, the main unit is working properly. You should check the control panel and field control wiring for problems next. 5. Remove the control panel from the mounting box and detach it from the field installed control wiring. Connect the blue, yellow, and green wires from the control panel directly to the corresponding colored pigtails on the main unit. Leave the violet, white, and red wires disconnected! 6. Turn on the fan switch; the impeller fan should run. Turn off the fan switch. 7. Turn on the humidity control; the compressor and impeller fan should run. 8. If these tests work, the problem is most likely in the field control wiring. 9.2 Refrigerant Charging If the refrigerant charge is lost due to service or a leak, a new charge must be accurately weighed in. If any of the old charge is left in the system, it must be recovered before weighing in the new charge. Refer to the unit nameplate for the correct charge weight and refrigerant type. 9.3 Compressor/Capacitor Replacement This compressor is equipped with a two terminal external overload and a run capacitor, but no start capacitor or relay. CAUTION-ELECTRICAL SHOCK HAZARD: Electrical power must be present to perform some tests. These tests should be performed by a qualified service person. 11