Refrigerator Troubleshooting Diagram

Archive for the ‘Condensing Unit’ tag

Condensing Unit And Evaporator Not Working

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■     Check the settings on the thermostat. Is unit turned on and is the temperature high enough to be calling for the unit to operate.

■     If unit fails to come on, turn fan control switch of the sub-base to the constant run position. If the fan comes on, low voltage is present in the system. If it doesn’t come on, there is no low volt­age in the system. Check at the transformer for secondary voltage. If not present, check the primary.

No primary voltage —        Check fuse that supplies the unit.

No secondary voltage —    Bad transformer.

Both primary and secondary voltage present – Check at sub-base of thermostat for 24 volts.

Voltage present at sub-base — Replace sub-base and thermostat.

Voltage not present at sub-base — Control wiring from transformer to thermostat defective.

Written by sam

November 15th, 2019 at 8:38 am

Condensing Unit And Evaporator Section

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There are times when everything appears to be operating according to all specifications, yet, insufficient cooling is the

Heat strips energizing with cooling-Check the heat relay in the air handler and see if there is 24 volts being applied to the holding coil.

The resistive heaters would counteract the cooling effect. Sometimes the contacts of a heat relay weld in the closed position, causing this. If 24 volts are found at the relay when the thermostat mode is in cooling, you must check the system circuitry. Disconnecting for the summer is alright; however, you will have to isolate the problem sooner or later. The source should be found in the evaporator section. It is either receiving its voltage from the thermostat or the defrost device in the condensing unit, if it is a heat pump. Sub-bases are sometimes the blame. They distort on an uneven wall surface causing them to crack or short circuit.

Written by sam

December 24th, 2010 at 9:11 am