Adjust Blower Off Delay (Heat Mode); Set Thermostat Heat Anticipator; Check Safety Controls - Carrier 58MTB Installation, Start-Up, And Operating Instructions Manual

Table 17–Speed Selection
LEAD COLOR SPEED
White Common
Black High
Yellow Med-High
Orange† Med
Blue Med-Low
Red Low*
* Continuous blower speed
† Available on 5-speed blowers only
For low-heat, the following connections can be made at LO
-HEAT on control:
a. Med (Orange) -Available only on 5-speed motors
b. Med-Low (Blue)
c. Low (RED) - Factory setting.
To change blower motor speed selections for heating mode,
remove blower motor lead from control HI-HEAT terminal. (See
Fig. 37.) Select desired blower motor speed lead from one of the
other motor leads and relocate it to HI-HEAT terminal. See Table
17 for lead color identification. Reconnect original lead on SPARE
terminal. Follow this same procedure for proper selection of
LO-HEAT and COOL speed selection.
Set Blower Off Delay
a. Remove Blower Access Door if installed.
b. Turn Dip switch 2 and 3 ON or OFF for desired blower off
delay. See Table 11A and B or Fig. 36 and 37.

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. See Table 11 for position of switches and
Fig. 36 or 37 for location of switches on control center.

SET THERMOSTAT HEAT ANTICIPATOR

When using a nonelectronic thermostat, the thermostat heat-
anticipator must be set to match the amp draw of the electrical
components in R-W/W1 circuit. Accurate amp draw readings can
be obtained at thermostat subbase terminals R and W.
Fig. 54 illustrates an easy method of obtaining actual amp draw.
The amp reading should be taken after blower motor has started
and furnace is operating in low heat. To operate furnace in
low-heat, first move SW-1 to ON position, then connect ammeter
wires as shown in Fig. 54. The thermostat anticipator should NOT
be in the circuit while measuring current. If thermostat has no
subbase, the thermostat must be disconnected from R and W/W1
wires during current measurement Return SW-1 to final desired
location after completing the reading.
See thermostat manufacturer's instructions for adjusting heat
anticipator and for varying heating cycle length.
When using an electronic thermostat, set cycle rate for 3 cycles per
hour.
Step 6—Check Safety Controls
This section covers the safety controls that must be checked before
the installation is complete. The flame sensor, gas valve, and
pressure switch were all checked in the Start-up procedure section
as part of normal operation.
1. Check Primary Limit Control
This control shuts off gas control system and energizes
air-circulating blower motor if furnace overheats.
Recommended method of checking this limit control is to
AS SHIPPED
C
OM
Cool
SPARE
High-Gas Heat
Spare/High-Gas Heat
Low-Gas Heat
57
THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
R Y W G
10 TURNS
FROM UNIT 24-VOLT
TERMINAL BLOCK
5.0 AMPS ON AMMETER
EXAMPLE:
10 TURNS AROUND JAWS
Fig. 54—Amp Draw Check with Ammeter
gradually block off return air after furnace has been operating
for a period of at least 5 minutes. As soon as limit control has
shut off burners, return-air opening should be unblocked to
permit normal air circulation. By using this method to check
limit control, it can be established that limit is functioning
properly and operates if there is a restricted return-air supply
or motor failure. If limit control does not function during this
test, cause must be determined and corrected.
2. Check Pressure Switch
This control proves operation of draft inducer. Check switch
operation as follows:
a. Turn off 115-v power to furnace.
b. Remove outer furnace 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 igniter
should not glow, and status code LED flashes a Status
Code 32. If hot surface ignitor glows when inducer motor
is disconnected, shut furnace down immediately. Deter-
mine reason pressure switch did not function properly and
correct condition.
e. Turn off 115-v power to furnace.
f. Reconnect inducer motor leads, reinstall main furnace door,
and turn on 115-v power supply.
HOOK-AROUND
VOLT/AMMETER
= 0.5 AMPS FOR THERMOSTAT SETTING
A80201