Page 14
VI−TYPICAL OPERATING CHARACTERISTICS
A−Blower Operation and Adjustment
NOTE− The following is a generalized procedure and
does not apply to all thermostat controls.
1− Blower operation is dependent on thermostat con-
trol system.
2− Generally, blower operation is set at thermostat sub-
base fan switch. With fan switch in ON position, blower
operates continuously. With fan switch in AUTO posi-
tion, blower cycles with demand.
3− In all cases, blower and entire unit will be off when the
system switch is in OFF position.
B−External Static Pressure
1− Measure tap locations as shown in figure 14.
FIGURE 14
STATIC PRESSURE TEST
MANOMETER
SUPPLY
RETURN
UNIT SHOWN IN
HORIZONTAL DISCHARGE LEFT POSITION
2− Punch a 1/4" (6mm) diameter hole in supply and return
air plenums. Insert manometer hose flush with inside
edge of hole or insulation. Seal around the hose with
permagum. Connect the zero end of the manometer to
the discharge (supply) side of the system. On ducted
systems, connect the other end of manometer to the re-
turn duct as above. For systems with non−ducted re-
turns, leave the other end of the manometer open to the
atmosphere.
3− With only the blower motor running and the evapora-
tor coil dry, observe the manometer reading. Adjust
blower motor speed to deliver the air desired accord-
ing to the job requirements.
4− For best air performance external static pressure
drop must not exceed 0.5" W.C. (1.2 kPa). Refer to
blower data tables for cfm and external static.
5− Seal around the hole when the check is complete.
C−Blower Speed Taps
Change Blower Speed
WARNING
Electric shock hazard! − Disconnect all
power supplies before servicing.
Replace all parts and panels before
operating.
Failure to do so can result in death or
electrical shock.
1. Disconnect all power supplies.
2. Remove the air handler access panel.
3. Locate pin number 2 on the blower relay. Two black
wires are connected to this terminal pin. One connects
to pin number 5 on the blower relay, one connects to an
inline splice connecting to a red or blue wire.
4. Remove the wire going to the 4−pin blower motor con-
nector from the splice.
5. Connect the blower lead [Red (LO), Black (HI)] onto the
splice from the 4−pin blower motor connector.
NOTE − Unused blower speed taps are factory−cov-
ered with plastic caps. Remove this cap from the de-
sired blower speed tap and replace it over the factory−
set blower tap.
6. Replace all panels.
7. Reconnect power.
VII−MAINTENANCE
WARNING
Disconnect power before performing any
maintenance.
At the beginning of each heating/cooling season, the sys-
tem should be checked as follows:
A−Filters
NOTE− Filter access panel must be in place during unit
operation, or excessive warm air may enter the unit re-
sulting in water blow−off problems.
TABLE 5
Unit Air Filter Size Chart
Model
Filter Size
18 / 24
16" x 20"
30 / 36
18" x 20"
42 / 48 / 60
18" x 25"
To remove filter, remove 1/4" head screws holding the fil-
ter panel in place. Slide filter out of the guides on either
side of cabinet, insert new filter and replace panel. Fil-
ters should be inspected monthly and must be replaced
when dirty to ensure proper blower coil operation. See
table 5 for replacement filter sizes.
B−Supply Air Blower
1- Check and clean blower wheel.
2- Motors are prelubricated for extended life; no further lu-
brication is required.
C−Electrical
1- Check all wiring for loose connections.
2- Check circuit breaker located in unit control box.
3- Check for correct voltage at unit (unit operating).
4- Check amp-draw on blower motor.
5- Check to see that heat (if applicable) is operating.