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What do you do to check if blower motor is getting power?

While the T-Stat is on or off, You use the jumper wire from 24 volt on furnace to fan on furnace. If the blower motor comes on then you have power to blower motor.


What is the recommended height to position a thermostat?

5 Feet.


Preliminary System Diagnostics for a clean and check: (List at least five).

-Check thermostat.
-Check condensate drain.
-Check filters.
-Check indoor coil for cleanliness.
-Check indoor blower motor.
-Check the wiring for indoor unit.
-Check outdoor blower motor.
-Check outdoor coil for cleanliness.
-Check the wiring for outdoor unit.


What steps should be taken if the compressor is having problems starting up?

-Check for power.
-Check starting relay.
-Check capacitor.
-Check compressor windings.
-Check refrigerant levels for proper charge.


What could cause the system to run continuously?

-High heat load.
-Undersized unit.
-System undercharged.
-Dirty condenser.
-Outdoor fan not operating up to speed on condenser.
-Time delay relay is stuck closed.


High superheat could be caused by:

-High heat load.
-Dirty condenser.
-Clogged filter drier.


Low superheat is caused by:

-Poor airflow across evaporator.
-Overcharged system.
-Low heat load.


High subcooling could be caused by:

-High heat load.
-Overcharged system.
-Dirty condenser.
-Clogged filter drier.


Low subcooling could be caused by:

-Undercharged system.
-Low heat load.


When obtaining accurate superheat or subcooling, one must:

-Make sure the system has been running for at least 15 minutes.

-Make sure there is a 15-25 degree difference across the evaporator coil. Preferably 18-22.


Suction line P-T measurements are needed to determine the:

-Air temperatures entering and leaving the evaporator coil.
-Amount of refrigerant in the system.
-Subcooling of refrigerant leaving a condensing coil.
-Superheat in the refrigerant leaving an evaporator.


How to calculate Superheat

1. Check suction pressure at the suction service valve.
2. Convert the suction pressure to temperature on the manifold set.
3. Place a temperature probe on the suction line near suction service valve.
4. The difference between step 2 and 3 is the superheat!


How to determine subcooling:

1. Check high side pressure at the liquid line access port.
2. Convert liquid line pressure to temperature on the manifold set.
3. Place temperature probe on the liquid line leaving the condenser.
4. The difference between steps 2 and 3 is your subcooling!


Make sure the supply voltage is within _______ when starting the equipment.

+ or - 10%.


What electrical checks should you do when dealing with a compressor?

-Compressor amperage. (Amps)
-Compressor windings. (Continuity)