Carrier 58MVP ÐWith DE Connection, ÐWithout DE Connection, ÐBypass Humidifier Mode, ÐZone Mode

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 9ÐBypass 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.

VARIABLE-SPEED

THERMIDISTATCONDENSING FURNACE

24 VAC HOT R R

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 COM terminal on the furnace control or the humidistat output and COM 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.

		VARIABLE-SPEED
THERMIDISTAT		CONDENSING
			FURNACE
24 VAC HOT	R				R
DEHUMIDIFY	DHUM				DEHUM
					DE
				NOTE 1
24 VAC COMM	C			Com

NOTE 1 - Remove DE Connection

To Enable DEHUM Input

DEHUM

Fig. 3ÐWith DE Connection

A98295

DEHUMIDIFY	DHUM	Com
24 VAC COMM	C

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 11ÐZone Mode

Fig.2ÐWithout DE Connection

Step 10ÐDehumidification Mode

A98294

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,

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

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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