Carrier 50PTH, PTV Operate ECM Interface Board, Cooling Settings, Dehumidificaton Mode Settings

Step 10 — Operate ECM Interface Board

STANDALONE — NO DDC CONTROLS — The ECM fan is controlled by an interface board that converts thermostat inputs and field selectable cfm settings to signals used by the ECM (electronically commutated motor) controller. See Fig. 32.

NOTE: Power must be off to the unit for at least three seconds before the ECM will recognize a speed change. The motor will recognize a change in the CFM Adjust or Dehumidification mode settings while the unit is powered.

There are four different airflow settings from lowest airflow rate (speed tap 1) to the highest airflow rate (speed tap 4). Tables 9-13 indicate settings for the ECM interface board, fol- lowed by detailed information for each setting.

CAUTION

When the disconnect switch is closed, high voltage is pres- ent in some areas of the electrical panel. Exercise caution when working with energized equipment.

Cooling — The cooling setting determines the cooling (nor- mal) cfm for all units with ECM motor. Cooling (normal) set- ting is used when the unit is not in Dehumidification mode. Tap 1 is the lowest cfm setting, while tap 4 is the highest cfm set- ting. To avoid air coil freeze-up, tap 1 may not be used if the Dehumidification mode is selected. See Table 9.

	Table 9 — Cooling Settings
TAP SETTING		DIP SWITCH
		SW1	SW2
1		ON	ON
2		ON	OFF
3		OFF	ON
4		OFF	OFF

Heating — The heating setting determines the heating cfm for 50PTH,PTV,PTD units. Tap 1 is the lowest cfm setting,

Dehumidification Mode — The dehumidification mode setting provides field selection of humidity control. When op- erating in the normal mode, the cooling airflow settings are de- termined by the cooling tap setting in Table 12.

Table 12 — Dehumidificaton Mode Settings

TAP SETTING	DIP SWITCH
	SW9
NORM	ON
Dehumid	OFF

When dehumidification is enabled, there is a reduction in airflow in cooling to increase the moisture removal of the heat pump. The Dehumidification mode can be enabled in two ways:

1.Constant Dehumidification mode: When the Dehumidifi- cation mode is selected via DIP switch, the ECM will operate with a multiplier applied to the cooling CFM settings (approximately 20 to 25% lower airflow). Any time the unit is running in the Cooling mode, it will oper- ate at the lower airflow to improve latent capacity. The “DEHUM” LED will be illuminated at all times. Heating airflow is not affected.

NOTE: Do not select Dehumidification mode if cooling setting is tap 1.

2.Automatic (humidistat-controlled) Dehumidification mode: When the Dehumidification mode is selected via DIP switch AND a humidistat is connected to termi- nal DH, the cooling airflow will only be reduced when the humidistat senses that additional dehumidification is required. The DH terminal is reverse logic. Therefore, a humidistat (not dehumidistat) is required. The

“DEHUM” LED will be illuminated only when the hu- midistat is calling for Dehumidification mode. Heat-

ing airflow is not affected.

NOTE: Do not select Dehumidification mode if cooling setting is tap 1.

while tap 4 is the highest cfm setting. See Table 10.

Table 10 — Heating Settings

TAP SETTING		DIP SWITCH
	SW3		SW4
1	ON		ON
2	ON		OFF
3	OFF		ON
4	OFF		OFF

CFM Adjust — The CFM Adjust setting allows four selec- tions. The NORM setting is the factory default position. The + or – settings adjust the airflow by ±15%. The + or – settings are used to “fine tune” airflow adjustments. The TEST setting runs the ECM at 70% torque, which causes the motor to operate like a standard PSC motor, and disables the cfm counter. See Table 11.

Table 11 — CFM Adjust Settings

1/4" SPADE

CONNECTIONS

TO COMPLETE C OR DELUXE D BOARD

THERMOSTAT

CONNECTIONS

DEHUMIDIFICATION

LED

TB1 R C Y2 Y1 G O W C R DH AL1 A A AL1

G Y1 Y2 O W

G G G G R

				CFM	Y
G		SW2 SW3 SW4 SW5 SW6 SW7 SW8 SW9	SW1
DEHUM	OFF ON			S1	J1

THERMOSTAT

INPUT LEDS

CFM COUNTER

1 FLASH PER 100 CFM

ECM MOTOR

LOW VOLTAGE

CONNECTOR

TAP SETTING		DIP SWITCH
	SW7		SW8
TEST	ON		ON
–	ON		OFF
+	OFF		ON
NORM	OFF		OFF

FAN SPEED SELECTION DIP SWITCH

Fig. 32 — ECM Interface Board Physical Layout

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