66
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal injury
or death.
Disconnect 115vac electrical power before changing speed tap.
!
WARNING
For low--heat, the following connections can be made at LO HT on
control:
a. Orange blower motor lead
b. Red blower motor lead -- Factory Setting
(Read following caution before changing taps).
UNIT DAMAGE HAZARD
To avoid operating outside the rise range and avoid
component damage:
Refer to the Air Delivery Tables to determine which airflows
and settings are allowed for proper heating airflow. DO NOT
use the highlighted settings for High--Stage Heating airflow.
The highlighted settings are to be used for Low--Stage Heating
and Cooling ONLY.
CAUTION
!
Change the blower speed taps as required to maintain proper
temperature rise for Heating and Cooling as described above. To
change blower motor speed selections for heating mode, remove
blower motor lead from control HEAT terminal(s). See Fig. 36.
Select desired blower motor speed lead(s) from the other motor
leads and relocate it/them to LO HT (low stage heat, low stage cool
blower tap) or HI HT (high stage heat blower tap) terminal(s).
Reconnect original lead on SPARE terminal.
Adjust Blower Off Delay (Heat Mode)
If desired, the main blower off time delay period may be
lengthened or shortened when operating in the heating mode to
provide greater comfort. For position and location of switches on
control center. See Fig. 36 and 69.
1. Remove blower door if installed.
2.TurnSetupswitchSW--2 andSW--3ONorOFFfor
desired blower off delay. See Table 18 and Fig. 36 and 69.
3. Proceed to “Set Blower Off Delay” before installing blower
door.
Adjust Cooling Airflow
The cooling airflow can be set from the remaining blower speed
taps. Refer to the Air Delivery Tables in these instructions.
If a two--stage air conditioning or heat pump is installed, the Low
Cooling Speed is the same speed tap as the Low Heat speed (LO
HT).
Adjust Continuous Fan Airflow
The Continuous Fan airflow can be set from the remaining blower
speed taps. Refer to the Air Delivery Tables in these instructions.
The Continuous Fan speed can be changed to any other speed tap
by toggling the Fan switch at the thermostat. See the Sequence of
Operation for details.
FURNACE OVERHEATING HAZARD
Failure to follow this caution may result in reduced furnace
life.
Recheck temperature rise. It must be within limits specified
on the rating plate. Recommended operation is at the
mid--point of rise range or slightly above.
CAUTION
!
Adjust Thermostat Heat Anticipator
Mechanical thermostat. Set thermostat heat anticipator to match
the amp. draw of the electrical components in the R--W/W1 circuit.
Accurate amp. draw readings can be obtained at the wires normally
connected to thermostat subbase terminals, R and W. The
thermostat anticipator should NOT be in the circuit while
measuring current.
1. Set SW--1 (LHT) switch on furnace control board to ON.
2. Remove thermostat from subbase or from wall.
3. Connect an amp. meter across the R and W subbase
terminals or R and W wires at wall.
4. Record amp. draw across terminals when furnace is in low
heat and after blower starts.
5. Set heat anticipator on thermostat per thermostat
instructions and install on subbase or wall.
6. Turn SW--1 (LHT) switch OFF.
7. Install blower access door.
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 procedure section as part of normal operation.
1. Check Main Limit Switch This control shuts off
combustion system and energizes air--circulating blower
motor, if furnace overheats. By using this method to check
the temperature limit control, it can be established that the
limit is functioning properly and that the limit will operate if
there is a restricted return--air supply or motor failure. If the
limit control does not function during this test, the cause
must be determined and corrected.
a. Run furnace for at least 5 minutes.
b. Gradually block off return air with a piece of cardboard or
sheet metal until the limit trips.
c. Unblock return air to permit normal circulation.
d. Burners will re--light when furnace cools down.
2. Check Pressure Switch(es)
This control proves operation of the draft inducer blower.
a. Turn off 115--v power to furnace.
b. 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
pressureswitch isfunctioning properly, hot surface igniter
should NOT glow and control diagnostic light flashes a
status code 32. If hot surface igniter glows when inducer
motor is disconnected, shut down furnace immediately.
e. Determine reason pressure switch did not function prop-
erly and correct condition.
f. Turn off 115--v power to furnace.
g. Reconnect inducer motor wires, replace outer door, and
turn on 115--v power.
h. Blowerwill runfor90 secbeforebeginning thecall forheat
again.
i. Furnace should ignite normally.
925TA
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