Operation below 0F Outdoor Temperature

IN ALL THREE RESET METHODS DESCRIBED ABOVE, A FIVE MINUTE TIME DELAY WILL TAKE PLACE AFTER THE RESET BEFORE THE UNIT WILL RESTART.

8.Supplemental electric heat (if installed) will be controlled by second stage TH2 of the thermostat. The supplemental electric heat circuit is controlled through low voltage termi- nals W, 60 and 66. The standby portion of electric heat (controlled through low voltage terminal 53) cannot operate because relay 4R is energized, opening the circuit to termi- nal 53, whenever the compressor is operating.

9.When second stage heating TH2 is satisfied, the supple- mental heaters will be de-energized.

0DEFROSTCYCLE

1.Adefrost cycle will be initiated by the defrost control board's timed defrost feature.

2.When the defrost cycle is initiated, the unit operates as fol- lows:

a.The reversing valve solenoid is energized through the defrost control board causing the unit to switch to the cooling cycle.

b.Defrost control board de-energizes 2M contactor, caus- ing the outdoor section fan(s) to shut down.

c.Supplemental electric heat (if installed) will be ener- gized through defrost control board. Only that portion of electric heat controlled through low voltage control ter- minal 66 will be energized by the defrost cycle. The op- eration of supplemental electric heat during unit defrost will prevent cold drafts in the conditioned space.

3.The defrost cycle will be terminated when:

a.the liquid temperature exceeds 55°F, or

b.10 minutes have passed since defrost initiation.

The 10 minute cycle time (independent of liquid line tem- perature)!1)is controlled by the defrost control board.

4. At defrost termination, the unit returns to the normal heat- ing operation.

OPERATION BELOW 0°F OUTDOOR

TEMPERATURE

1. At 0°F outdoor temperature, the low temperature compres- sor cutoff thermostat 1TH contacts 1 and 3 will open, de- energizing contactor 1M which shuts down the compres- sor. Contacts 1 and 2 of thermostat 1TH are closed when contacts and 3 are open. This feature allows the standby electric heat (if installed) to operate under control of first stage heating TH1 of the room thermostat whenever the compressor is shut-down by the 1TH control. The supple- mental electric heat will continue to be controlled by the second stage TH2 of the room thermostat same as de- scribed under Item 8 of HEATING OPERATION.

2. The indoor section blower operation will be controlled by the first stage heating TH1 of the room thermostat if the fan switch is in the “AUTO” position.

0EMERGENCY+.=HEAT;%OPERATION,

1.The emergency heat light on the room thermostat will be energized.

2.Compressor will not operate because the Y circuit of the room thermostat cannot be energized.

3.Supplemental and standby electric heat (if installed) will be controlled by first stage heating TH1 of room thermostat.

4.Indoor section blower will also be controlled by first stage heating TH1 if fan switch is in the “AUTO” position.

14	Unitary Products Group