Carrier 50VL---A Continuous Fan Operation, Cooling Sequence Of Operation, Interface Fan Board IFB

50VL-- A

HIGH

STD DEHUM

LOW

COM

QC5

QC4

QC3

KZ

KL

QCR

DCR

R13

C8

R11

Q1

C

CDM/C

07

09

0L0

08

ALO

D2

QC1

Q3

AL2

24VAC/R

C9

C4

G1

RL

01

G2

3AMP

QIL

Z2

06

04

A7

R9

AB

A15

C0

F1

U1

Z1

C3

R4

RL4

D5

D3

C7

JWZ

P3

R2

JW5

R3

R5

R6

P2

JW3

QCB

P4

SDL

Y

R

W2 Y

C

W3 W3 W2 W2 C

JW4

SSTZ-8

P1

Y2

Y1

W3 W2

G

C

R

DH

Y

A09059

Fig. 11 - Interface Fan Board (IFB)

SINGLE SPEED COOLING WITH HIGHER ELECTRIC HEAT SPEED

This unit can also be configured to operate with single speed cooling and a higher speed for an accessory electric heater.

1.Using Fig. 11, move the two pin DEHUM jumper from the “STD” position to the “DEHUM” position.

2.See Table 2 for minimum airflow for electric heat operation. Add electric heater and filter pressure drop to duct system static pressure to determine total external static pressure.

3.Select speed tap from Table 4 that will achieve required airflow from Table 2.

4.Remove the vinyl cap off of the desired speed tap wire (Refer to Table 3 for color coding).

5.Connect the desired speed tap wire to the “HIGH” terminal on the interface fan board (IFB).

!CAUTION

UNIT OPERATION HAZARD

Failure to follow this caution may result in unit component damage or improper operation.

To use this mode, a speed connection must be made on the “HIGH” terminal that meets or exceeds the minimum airflow found in Table 2.

Table 3 – Color Coding for Indoor Fan Motor Leads

Black = High Speed

Orange = Med--High Speed

Red = Med Speed

Pink = Med--Low Speed

Blue = Low Speed

!WARNING

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal injury or death.

Disconnect electrical power to the unit and install lockout tag before changing blower speed.

CONTINUOUS FAN OPERATION

When the DEHUM feature is not used, the continuous fan speed will be the same as cooling fan speed. When the DEHUM feature is used, the continuous fan will operate on IFB “LOW” speed when the DH control lead is not energized, or IFB “HIGH” speed when the DH lead is energized (see Fig. 11).

COOLING SEQUENCE OF OPERATION

With the room thermostat SYSTEM switch in the COOL position and the FAN switch in the AUTO position, the cooling sequence of operation is as follows:

When the room temperature rises to a point that is slightly above the cooling control setting of the thermostat, the thermostat completes the circuit between thermostat terminal R to terminals Y and G. These completed circuits through the thermostat connect contactor coil (C) (through unit wire Y) and time delay relay (TDR) (through unit wire G) across the 24-V secondary of transformer (TRAN).

The normally open contacts of energized contactor (C) close and complete the circuit through compressor motor (COMP) to condenser (outdoor) fan motor (OFM). Both motors start instantly.

A set of normally open contacts on the interface fan board (IFB) are closed which energizes a circuit to the indoor fan motor (IFB).

NOTE: Once the compressor has started and then has stopped, it should not be started again until 5 minutes have elapsed.

The cooling cycle remains on until the room temperature drops to a point that is slightly below the cooling control setting of the room thermostat. At this point, the thermostat breaks the circuit between thermostat terminal R to terminals Y and G. These open circuits deenergize contactor coil C and IFB. The condenser and compressor motors stop. After a 90-second delay, the blower motor stops. The unit is in a standby condition, waiting for the next call for cooling from the room thermostat.

14