Carrier FV4B - PROCEDURE 11-TROUBLESHOOTING ECM MOTOR AND CONTROLS; ECM Motor Troubleshooting

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F. Dehumidify and Super Dehumidify Capabilities

This model fan coil is capable of responding to a signal from indoor system control (Thermidistat, zoning control) to operate in comfort control

modes such as Super Dehumidify Mode. Consult literature provided with indoor system control to determine if these operating modes are available,

and to see control set up instructions. No special setup or wiring of fan coil is required.

PROCEDURE 10—FV4B FAN COIL SEQUENCE OF OPERATION

The FV4B will supply airflow in a range which is more than twice the range of a standard fan coil. It is designed to provide nominal cooling

capacities at a 50°F evaporator temperature and the required airflow which enables it to match with 4 air conditioner or heat pump system sizes.

Table 2 outlines the CFM range for the different FV4B Fan Coil sizes.

A. Continuous Fan

• Thermostat closes circuit R to G.

• The blower runs at continuous fan airflow.

B. Cooling Mode - Single speed

• If indoor temperature is above temperature set point and humidity is below humidity set point, thermostat closes circuits R to G, R to Y/Y2

andRtoO.

• The fan coil delivers single speed cooling airflow.

C. Cooling Mode - Dehumidification

• If indoor temperature is above temperature set point and humidity is above humidity set point, thermostat or Thermidistat™ closes circuits R

to G, R to O, and R to Y/Y2, and humidistat or Thermidistat opens R to DH.

• The fan coil delivers airflow which is approximately 80 percent of the nominal cooling airflow to increase the latent capacity of the system.

D. Cooling Mode - Super Dehumidify Operation (See Fig. 22 for Quick Reference Guide)

NOTE: The indoor control used, such as Thermidistat, must be capable of providing Super Dehumidify operation mode and control must be

configured as outlined in its installation instructions. Consult indoor control literature to determine if control is capable of providing Super

Dehumidify inputs and for configuration instructions.

If the indoor temperature is below the temperature set point and the humidity is above the humidity set point, the Thermidistat closes circuit R

to O, opens circuits R to DH and R to G, and cycles circuit R to Y/Y2 (for single speed system R to Y1, or R to Y1 and Y/Y2 for 2-speed system).

The ECM motor reads the G signal to the fan coil while the heat pump is operating, (circuit R to Y/Y2 for single speed system, R to Y1 or R to

Y1 and Y/Y2 for 2-speed system), closed (24 vac). If circuit R to G is closed (24 vac), the motor will deliver airflow at the full cooling or cooling

plus dehumidify mode requested value. If circuit R to G is open (0 vac) for super dehumidify mode, the motor delivers reduced airflow to maximize

the humidity removal of the system while minimizing overcooling.

E. Electric Heat Heating Mode

• Thermostat closes circuit R to W/W1, or W2.

• The fan coil delivers the selected electric heat airflow.

F. Heat Pump Heating Mode - Single speed

• Thermostat closes circuits R to G and R to Y/Y2.

• The fan coil delivers single speed heat pump heating airflow.

G. Heat Pump Heating with Auxiliary Electric Heat

Thermostat closes circuits R to G, R to Y/Y2 and/or R to Y1 with R to W/W1 or W2 (and R to O in the case of defrost).

In the event that electric heating is called for by the thermostat while the heat pump is also operating in either heating or defrost modes, the motor

will modify its airflow output, if necessary, to provide an airflow which is defined as safe for the operation of the electric heater during heat pump