Adjust Thermostat Heat Anticipator; Check Safety Controls - Carrier 59SC2D Installation, Start-Up, Operating And Service And Maintenance Instructions

WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Reinstall manifold pressure tap plug in gas valve to prevent
gas leak.
CAUTION
!
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.

Adjust Thermostat Heat Anticipator

Mechanical thermostat: Set thermostat heat anticipator to match
the amp draw of the electrical components in the R- -W circuit.
Accurate amp draw readings can be obtained at the wires normally
connected to thermostat subbase terminals R and W.
thermostat anticipator should NOT be in the circuit while
measuring current.
1. Remove thermostat from subbase or from wall.
2. Connect an amp meter across the R and W subbase termi-
nals or R and W wires at wall. See Fig. 65.
3. Record amp draw across terminals when furnace is in low
heat and after blower starts.
4. Set heat anticipator on thermostat per thermostat instruc-
tions and install on subbase or wall.
5. Install blower access door.
Electronic thermostat: Set cycle rate for 3 cycles per hr.
THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
(ANITICIPATOR, CLOCK, ETC.,
MUST BE OUT OF CIRCUIT.)
R Y W G
10 TURNS
FROM UNIT 24-V
CONTROL TERMINALS
EXAMPLE: 5.0 AMPS ON AMMETER
10 TURNS AROUND JAWS
Fig. 65 - - Amp. Draw Check with Ammeter

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.
The
HOOK-AROUND
AMMETER
= 0.5 AMPS FOR THERMOSTAT
ANTICIPATOR SETTING
A96316
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 es-
tablished 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
low pressure switch is functioning properly, hot surface
ignitor should NOT glow and control diagnostic light
flashes a status code 31. If hot surface ignitor glows when
inducer motor is disconnected, shut down furnace immedi-
ately.
e. Determine reason low pressure switch did not function
properly and correct condition.
f. Turn off 115- -v power to furnace.
g. Reconnect inducer motor wires, replace door, and turn on
115- -v power.
h. Blower will run for 90 sec before beginning the call for
heat again.
i. Furnace should ignite normally.
Checklist
1. Put away tools and instruments. Clean up debris.
2. Verify that the jumper is removed from the TEST/TWIN
terminal. Verify that there is nothing plugged into the PLT
connector. (Note: If there is a jumper connector plugged
into PLT, remove it and discard.) See Fig. 37.
3. Verify that the Blower/Heat Off Delay jumpers are set as
desired. See Fig. 37 and 73.
4. Verify that the blower (lower door in upflow position) and
control ("Main" or upper door in upflow position) doors are
properly installed.
5. Verify that the Status LED glows. If not, check that the
power supply is energized and that the blower door is
secure. See Fig. 66 to interpret diagnostic codes.
6. Cycle test furnace with room thermostat to be sure that it
operates properly with the room thermostat. Check all
modes including Heat, Cool and Fan.
7. Check operation
instructions.
8. Review Owner's Manual with owner.
9. Attach entire literature packet to furnace.
58
of accessories per manufacturer's