Disconnect the electrical power before changing the speed
tap. Failure to follow this warning could result in personal
injury.
d. To change blower motor speed selections for heating mode
remove blower motor lead from control board HEAT
terminal. (See Fig. 13.) Select desired blower motor speed
lead from 1 of the other terminals and relocate it to HEAT
terminal. See Table 10 for lead color identification. Recon-
nect original lead on SPARE terminal.
Follow this same procedure for proper selection of COOL
speed selection.
If Model 58ZAV115-22 is installed in 0.50-in. wc or lower
static pressure ductwork, evaporator coil condensate blow off
can occur during cooling operation. When installed in this
msnner, do not use high blower speed tap for cooling.
Recheck temperature rise. It must be within limits specified
on unit rating plate. Recommended operation is at midpoint of
rise or above.
3. Set thermostat heat anticipator.
The thermostat heat anticipation must be set to match the amp
draw of the electrical components in the R-W circuit. Accurate
amp draw readings can be obtained at thermostat subbase
terminals R and W. Fig. 19 illustrates an easy method of
obtaining the actual amp draw. The amp reading should be
taken after the blower motor has started. See the thermostat
manufacturer’s instructions for adjusting the heat anticipator
and for varying the heating cycle length.
NOTE:
When using an electronic thermostat, set cycle rate for 3
cycles per hr.
CHECK SAFETY CONTROLS
The flame sensor, gas valve, and pressure switch were all checked
in the Start-up Procedures section as part of normal operation.
1. Check primary limit control.
This control shuts off the combustion control system and
energizes the circulating-air blower motor if the furnace
overheats.
The preferred method of checking the limit control is to
gradually block off the return air after the furnace has been
operating for a period of at least 5 minutes. As soon as the
limit has shut off the burners, the return-air opening should be
unblocked. By using this method to check the limit control, it
can be established that the limit is functioning properly and
operates if there is a motor failure.
2. Check draft safeguard switch.
The purpose of this control is to permit the safe shutdown of
the furnace during certain blocked vent conditions.
a. Disconnect power to furnace and remove vent connector
from furnace outlet collar. Be sure to allow time for vent
pipe to cool down before removing.
b. Restore power to furnace and set room thermostat above
room temperature.
c. After normal start-up, allow furnace to operate for 2
minutes, then block flue outlet 100 percent. Furnace should
cycle off within 2 minutes.
d. Remove blockage and reconnect vent pipe to furnace outlet
collar.
e. Wait 5 minutes and then reset draft safeguard switch.
3. Check pressure switch.
This control proves operation of draft inducer blower.
a. Turn off 115-v power to furnace.
b. Remove control door and disconnect inducer motor lead
wires from wire harness.
c. Turn on 115-v power to furnace.
d. Set thermostat to "call for heat" and wait 1 minute. When
pressure switch is functioning properly, hot surface ignitor
should NOT glow and control board diagnostic light
Table 10—Speed Selector
COLOR
SPEED
FACTORY-
ATTACHED TO
Black
High
COOL
Yellow (When
present)
Medium-High
SPARE
Blue
Medium-Low
HEAT
Red
Low
SPARE
White
Common
C
OM
Fig. 19—Amp Draw Check With Ammeter
A80201
R
Y W G
10 TURNS
THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
HOOK-AROUND
VOLT/AMMETER
EXAMPLE:
5.0 AMPS ON AMMETER
10 TURNS AROUND JAWS
= 0.5 AMPS FOR THERMOSTAT SETTING
FROM UNIT 24-VOLT
TERMINAL BLOCK
18
