Carrier 58MVP - Manual (Page 5)

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
A dehumidification input is provided via a 1/4-in. male quick-
connect terminal labeled DEHUM, located next to the transformer
secondary connections. The DEHUM input acts differently de-
pending on which style of variable speed furnace control you have.
The older style variable speed furnace control (shown in Fig. 1)
DOES NOT have a DE connection while the newer style variable
speed furnace control (shown in Fig. 1) has a DE connection. The
newer style variable speed furnace control is expected to be
available by mid 1998. Both of these variable speed furnace
controls function the same except the DEHUM logic is reversed.
This logic reversal has come about from historical use of a
standard humidistat to do dehumidification since the contacts open
on high humidity, thus removing the 24-v signal to initiate
dehumidification.
On the older style variable speed furnace controls, a field supplied
relay is required between the thermidistat or humidistat control and
furnace. The relay coil is connected between DHUM output on the
thermidistat control and C
OM terminal on the furnace control or the
humidistat output and C OM terminal on the furnace control. Its
normally closed contact is connected between R and DEHUM
terminals on the furnace control. (See Fig. 1 and Fig. 2). When a
dehumidify demand exists, relay is de-energized, and normally
closed contacts supply 24-v to the furnace DEHUM terminal. As
a result, the furnace control reduces the blower airflow by 15
percent to 340 CFM per ton during continuous fan or cooling
operation.
On newer style variable speed furnace controls, a field supplied
relay IS NOT required. The DEHUM output on the thermidistat
control or the humidistat output is connected directly to the
DEHUM terminal on the furnace control. In addition, the DE
jumper located next to the DEHUM terminal must be removed to
enable the DEHUM input. (See Fig. 1 and Fig. 3). When a
dehumidify demand exists, the furnace control reduces the blower
airflow by 21 percent to 315 CFM per ton during continuous fan
or cooling operation.
This blower speed reduction compensates for high humidity
conditions during cooling operation on all furnace model sizes.
Reference Thermidistat™ Control Installation, Start-up, and Op-
erating Instructions for further details.
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.
Fig.2—Without DE Connection
A98294
24 VAC HOT
DEHUMIDIFY
24 VAC COMM
R R
DHUM
DEHUM
C
Com
THERMIDISTAT
VARIABLE-SPEED
CONDENSING
FURNACE
Fig. 3—With DE Connection
A98295
24 VAC HOT
DEHUMIDIFY
24 VAC COMM
R R
Com
DHUM DEHUM
C
DE
NOTE 1
THERMIDISTAT
VARIABLE-SPEED
CONDENSING
FURNACE
NOTE 1 - Remove DE Connection
To Enable DEHUM Input
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