Carrier 58MVP Troubleshooting Manual page 4

NOTE: The blower starts at approximately 400-500 RPM. After
20 sec, the motor is turned off for 1/10 of a sec where a coast down
calibration is done to evaluate resistance of the conditioned air
duct system. The microprocessor then determines blower RPM
required to provide proper airflow for heating mode.
NOTE: The continuous fan speed is the same as low-heat speed
unless it is field adjusted to another desired airflow. See Continu-
ous Fan Setup Switches section in Installation, Start-Up, and
Operating Instructions for details. There is also a chart on
schematic diagram shown in Appendix A.
c. Electronic Air Cleaner—The EAC-1 terminal is ener-
gized whenever blower operates, regardless of operating
mode.
2. Operating with continuous fan (R-G) and call for heat
(R-W/W1) is received—Same as heat pump mode except
blower on delay is 10 sec less than the heat mode. After call
for heat (R-W/W1) is terminated, the blower remains operat-
ing at low-heat speed for selected blower off delay before
resuming continuous fan speed.
3. Operating with continuous fan (R-G) and call for cooling
(R-Y/Y2) is received—See Cooling Mode section. After call
for cooling (R-Y/Y2) is terminated, the blower remains
operating at cooling speed for 90 sec before resuming con-
tinuous fan speed.
Step 8—Component Test
All components are functionally operated except gas valve with
component test feature.
This feature helps diagnose a system problem in case of a
component failure.
NOTE: Setup switch SW-1 MUST be in OFF position or Fault
Code 22 (setup error) will occur.
NOTE: NO thermostat signal may be present at control center,
and all blower time delay off periods must be completed.
To initiate component test feature, proceed with the following:
1. Leave 115-v power to furnace turned on.
2. Remove main furnace door.
3. Remove blower access panel.
4. Turn setup switch SW-6 to ON position.
5. Manually close blower access panel door switch.
On some models, blower access panel door switch opens only
24-v power to control center. No component operation can
occur. The 115-v power is still present at control center,
transformer, inducer motor, and main blower motor. Caution
must be taken when manually closing this switch for service
purposes. Failure to follow this warning could result in
personal injury or death.
When items 1-5 have been completed, the following will occur:
1. The control center goes through a brief self test. This self test
takes approximately 2 sec to complete. After door switch is
closed, red (microprocessor) LED briefly comes on. Then
green LED comes on for 1 sec, followed by 1 sec where both
green and yellow LEDs are on. During this time, the micro-
processor is checking itself.
2. Inducer motor operates for 20 sec at low speed, operates 20
sec at high speed, then turns off.
3. Hot surface ignitor is energized for 15 sec, then de-energized.
4. Main blower motor operates for 20 sec at low speed, operates
for 20 sec at high speed, then turns off.
5. After component operation test is completed, 1 or more fault
codes (11, 22, 41, or 42) will flash. See service label on back
of main furnace door or Fig. 1 for explanation of fault codes.
NOTE: To repeat component test, turn setup switch SW-6 to OFF
and then back to ON.
After component test, perform the following:
1. Release blower panel access door switch and turn setup switch
SW-6 to OFF position.
2. If applicable, replace blower access panel and check LED
status by removing plug in blower access panel.
3. Reinstall main furnace door if all LEDs are off, indicating
furnace is ready to operate when a signal from thermostat is
received.
Step 9—Bypass Humidifier Mode
When setup switch SW-3 BPH is in ON position, RPM calculated
for low heat is multiplied by 1.15 for all furnace model sizes. This
compensates for increased return-air temperature caused by by-
passed air supply.
Step 10—Dehumidification Mode
If dehumidification input is energized with a 24-vac input, RPM
calculated for cooling and continuous fan is multiplied by 0.85 for
all furnace model sizes. This compensates for high humidity
conditions during cooling operation.
Step 11—Zone Mode
When setup switch SW-5 MZ is in ON position, blower motor
control is the same as above except with the following exceptions:
1. While blower is operating in either low heat or continuous fan,
the coast down calibration is performed once a minute to
update blower RPM for zone damper position changes during
a given cycle.
NOTE: Boards with date codes of 9506 or later will not perform
a coast down calibration if blower pulse width to blower motor is
greater than 60 percent. This prevents nuisance faults from
occurring when a high continuous fan CFM has been selected.
2. While blower is operating in either high heat or cooling,
blower pulse width to blower motor is frozen when blower
RPM is within 10 percent of calculated blower RPM for 5 sec.
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