9
Fan
Fig.4-2
Fan and motor assembly
Fig4-3
Flow-Check Pistons
refrigerant metering device controlling refrigerant flow into the evaporator. Second, it acts as an open
check valve when refrigerant flows in the opposite direction.
PROPER MATCH OF UNIT AND PISTON SIZES
Combinations for indoor and outdoor units using a distributor and flowcheck are shown in the application
Mismatching indoor and outdoor units of split systems affects performance, efficiency, charging and
reliability.
Distributor assy
Fig.4-4
Both compressor types are protected internally against over-current and over-temperature conditions.
the contactor coil.
FAN AND BLOWER MOTORS (Fig. 4-2 and Fig. 4-3)
The outdoor component of split system contains an fan motor. These PSC (permanent split capacitor)
Some scroll compressors have an additional thermostat mounted externally in series electrically with
motors are single speed and drive a propeller fan. The motor mounts to the unit top with the shaft up,
This fan pulls outdoor air through the outdoor coil.
To access the condenser fan or motor, carefully remove the unit top, a service loop is provided on the
motor wiring for easier access.
METERING DEVICES (Fig. 4-4)
One type of refrigerant metering device is the flow-check piston. It has two functions. First it acts as a
When refrigerant enters the device from the square end, the piston seats and forces all refrigerant throug
h
the carefully sized hole in the center of the piston. This orifice functions as a metering device controlling
the amount of refrigerant flow, with flow in the opposite direction, pressure moves the piston off the seat
and liquid refrigerant flows around the piston.
Using too small a piston starves the coils of refrigerant. A piston that is too large floods coils.
Split air conditioning indoor and outdoor units must be carefully matched to balance the heat transfer
indoors with the heat resected or claimed by the outdoor unit. Manufacturer's specification sheets and
installation manuals should be followed to insure proper match. Matched systems are listed on the
internet at ARI. ORG.
table 6-2.
Central Air Conditioner
Model: Cooling Only,
13
SEER
units
