Friedrich H)A09K25, V(E Electric Heat Switch Operation, Electric Heat Switch Check Out

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Emergency Heat Switch (Defrost Thermostat) Continuity Check

Electric Heat Switch Operation

(Heat Pumps Only)

The electric heat switch is a dual function control and is shown on the wiring diagram as a defrost thermostat. It may be adjusted using a screwdriver. As the control shaft is rotated counter clockwise a detent will be encountered. Turning the control past the detent will lock out the compressor and acts as an emergency heat switch. Turning the control shaft clockwise will lower the change over point for compressor operation. The control it self is a double throw, single pole switch operated by a bellows and a gas fi lled capillary tube. The capillary tube senses a combination of outdoor coil temperature and outdoor air temperature. As the combined temperatures reach a point that the outdoor coil is iced, where heat pump operation is no longer efficient, the control shuts off the compressor and turns on the electric heat. At its lowest setting the cut off point is approximately 25 degrees, the highest setting is 52 degrees, with a 10 degree differential. It is possible, under certain conditions, for the unit to cycle between compressor and electric heat operation.

Electric Heat Switch Check Out

The switch may be checked out with an ohmmeter. Remove and label the three wires from the switch. Terminal 2 is common and the contacts make to Terminal 3 on temperature rise and to Terminal 1 on temperature fall. With the control set in the emergency heat position continuity should be read between Terminal 2 and Terminal 1 regardless of coil temperature. As the control shaft is rotated clockwise, through the adjustment range, continuity will be read between Terminal 2 and Terminal 3, providing the temperature of the capillary tube is above 25º (± 5%). If the temperature at the capillary tube is above approximately 52 degrees it may be necessary to place the end of the capillary tube in ice water to determine if the control is sensing temperature changes. Should the control lose the gas charge in the capillary tube it will fail to the electric heat position and the compressor will not operate.

 

 

 

SWITCH POSITION

TEMPERATURE AT CAPILLARY

CONTINUITY READ

EMERGENCY HEAT

N/A

1 and 2 = Electric Heat

ANYWHERE IN

ABOVE SET POINT

2 and 3 = Compressor

ADJUSTMENT RANGE

 

 

ANYWHERE IN

BELOW SET POINT

1 and 2 = Electric Heat

ADJUSTMENT RANGE

 

 

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Contents VE,HA09K25 VE,HA09K34 VE,HA12K25 VE,HA12K34VE,HA18K25 VE,HA18K34 VE,HA24K25 VE,HA24K34Table of Contents Introduction Serial Number Identification Guide VERT-I-PAKH Suffix Chassis Specifications VERT-I-PAKE & G Suffix Chassis Specifications VERT-I-PAKA D Suffix Chassis Specifications Refrigeration Assembly Sequence of OperationElectrical Supply Supply CircuitSupply Voltage Control Low VoltageRoom Thermostats Heat AnticipatorsTypical Electrical & Thermostat Wiring Diagrams Typical Electrical & Thermostat Wiring Diagrams Suffix For 208 Volt Models only Move the White Wire AS Shown below Indoor Blower Airflow Condenser Fan MotorsBlower Wheel Inspection CoolingChecking External Static Pressure Checking Approximate AirflowElectric Heat Strips Explanation of charts Ductwork PreparationRefrigerant Charging Method Of Charging Undercharged Refrigerant SystemsOvercharged Refrigerant Systems Restricted Refrigerant SystemsTesting Coil Metering Device Capillary Tube SystemsReversing Valve Description/Operation Electrical Circuit and CoilChecking Reversing Valve Touch Test in Heating/Cooling CycleCompressor Checks From Electrical ShockSingle Phase Resistance Test Recommended Procedure for Compressor ReplacementCapacitors Capacitor ConnectionsElectric Heat Switch Operation Electric Heat Switch Check OutWiring Diagram Index VHA09K25RTG Suffix only Suffix only Suffix only Page Page Page Page Page Page Page Page Page Electrical Troubleshooting Chart Cooling TON Electrical Troubleshooting Chart Cooling Troubleshooting Chart Cooling Electrical Troubleshooting Chart Heat Pump Page Use Factory Certified Parts