3Com 43506 • Fresh Air Damper Assembly, Flame Should Groundengulf Sensor Strap Igniter

FIGURE 5

FLAME SHOULD

GROUNDENGULF SENSOR STRAP

IGNITER

SENSOR

MIS-1067

FIGURE 6

HEAT

EXCHANGER

SECTION

NO LIFTING AWAY FROM BURNER PORTS

OUTER CONE

INNER

CONE

SECTION 7 • AIR CONDITIONING START UP PROCEDURE CRANKCASE HEATERS

Single and three phase models have an insertion well-type heater located in the lower section of the compressor housing. This is a self-regulating type heater that draws only enough power to maintain the compressor at a safe temperature.

Some form of crankcase heat is essential to prevent liquid refrigerant from migrating to the compressor, causing oil pump out on compressor start-up and possible valve failure due to compressing a liquid.

The decal in Figure 7 is affixed to all outdoor units detailing start-up procedures. This is very important. Please read carefully.

FIGURE 7

IMPORTANT

These procedures must be followed at initial start-up and at any time power has been removed for 12 hours or longer.

To prevent compressor damage which may result from the presence of liquid refrigerant in the compressor crankcase.

1.Make certain the room thermostat is in the “off” position (the compressor is not to operate).

2.Apply power by closing the system disconnect switch. This energizes the compressor heater which evaporates the liquid refrigerant in the crankcase.

3.Allow 4 hours or 60 minutes per pound of refrigerant in the system as noted on the unit rating plate, whichever is greater.

4.After properly elapsed time, the thermostat may be set to operate the compressor.

5.Except as required for safety while servicing—Do not open system disconnect switch.

7961-061

SECTION 8 • FRESH AIR DAMPER ASSEMBLY

The fresh air damper assembly permits outside fresh air to be introduced to the building whenever the main unit comfort air blower is operating. The damper blade may be set to one of four positions: 1) full open, 2) 50% open, 3) full closed, or 4) automatic (barometric) operation. In the latter set-up the damper blade will open and close as the main comfort air blower cycles on and off. Reference Figure 8 for details on damper positions.

There is also a cleanable filter installed at the bottom opening of the fresh air damper that requires periodic cleaning. The cleaning interval will be dependent upon frequency of unit operation and local air conditions. See Figure 3 for Fresh Air Damper and filter locations.

FIGURE 8

FULL OPEN

NORMAL BAROMETRIC

POSITION

50% OPEN FIXED POSITION. (2) ADDTIONAL CANOE CLIPS ARE TAPED TO THE INSIDE OF

DAMPER ASSEMBLY

TOTALLY CLOSED

POSITON

MIS-957

Manual 2100-279 Page 10