Remove Fan Motor; Cleaning Coil; Two-Speed System; Cautions And Warnings - Carrier R-22 Application Manual And Service Manual

with an isolated compressor compartment, greatly reduces the
overall sound level of the unit. The unit utilizes front and back
seating valves. The heat-pump heating piston is a Chatleff-type.
(See Fig. 33.)
Step 2—Remove Fan Motor
1. Turn off power to unit.
2. Remove air-inlet grille.
3. Measure distance from outside top edge of fan blade to outside
edge of fan deck. (See Fig. 34.)
4. Remove fan blade.
5. Loosen cinch bolt holding bellyband around motor.
6. Unplug motor leads.
7. Spread bellyband and remove motor.
8. Reverse order to reinstall.
NOTE: When installing fan blade on motor, use dimension
measured in item 3.
SERVICE
VALVE
PISTON
WITH
ORIFICE
Fig. 33—Heat-Pump Service Valve/Piston
OUTSIDE EDGE OF
FAN DECK
OUTSIDE EDGE
OF GRILLE
Fig. 34—Fan Position
Step 3—Cleaning Coil
Coil should be washed clean with water or blown clean with
compressed air. The blow-through design causes dirt and debris to
build up on the inside of coil.
Clean coil annually or as required by location or outdoor air
conditions. Inspect coil monthly and clean as required. Fins are not
TEFLON SEAL
SCREEN
CAP
A92069
FAN BLADE
DIMENSION FROM
OUTSIDE TOP EDGE OF
BLADE TO OUTSIDE EDGE
OF FAN DECK.
A92070
continuous through coil sections. Dirt and debris may pass through
first section, become trapped between the rows of fins, and restrict
condenser airflow. Use a flashlight to determine if dirt or debris
has collected between coil sections. Clean coil as follows:
1. Turn off power to unit.
2. Flush coil from the outside to remove dirt using water from a
hose or other suitable equipment. Be sure to flush all dirt and
debris from drain holes in base of unit.

TWO-SPEED SYSTEM

Step 1—Cautions and Warnings
For proper unit operation and reliability, the 2-speed units
must be installed with the factory-supplied balance port, hard
shutoff TXV. Do not install with indoor coils having piston or
capillary-tube metering devices.
Do not install equivalent interconnecting tubing lengths
greater than 100 ft. Do not decrease or increase interconnect-
ing tubing diameters.
To avoid electrical shock, bleed resistor must be connected
across run capacitor. Replace if missing or damaged.
Contactor is mechanically interlocked. Do not disable me-
chanical interlock. Compressor damage may occur.
Contactor control voltage is 240vac.
Do not attempt to operate this equipment below 55°F outdoor
ambient temperature.
NOTE: Sections that follow describe the 38TDA and 38YDA
products, which started production March, 1994. For 38TD and
38YD products, refer to the Split-System Service Manual dated
3-94, Catalog No. 563–799.
Step 2—System Functions
COOLING OPERATION
The 2-speed products utilize a 2-stage-cooling indoor thermostat.
With a call for first-stage cooling (Y1), the outdoor fan and
low-speed compressor are energized. If low speed cannot satisfy
the cooling demand, high speed will be energized (Y1 and Y2) by
the second stage of the indoor thermostat. The thermostat has a 2°
differential between first and second stages. After second stage is
satisfied, the unit returns to low-speed operation until first stage is
satisfied or until second stage is again required.
HEATING OPERATION (HEAT PUMP ONLY)
The 2-speed products utilize a 2-stage-heating indoor thermostat.
The first stage of heating is heat-pump operation (Y1). Auxiliary
backup heat is controlled by second stage (W2). There is a 2°
differential between first and second stage. The control board
determines the compressor speed based on ambient temperature.
See Table 15 for ambient temperatures at which speed changes
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