Bryant 548F User Manual download pdf (Page 43)

—

Table 31 — Durablade Economizer Troubleshooting

LEGEND

PROBLEM CAUSE REMEDY

Damper does not

open.

Indoor fan is off. 1. Check to ensure that 24 vac is present at terminal C1 on the IFC or that 24 vac is

present at the IFO terminal. Check whether 24 vac is present at PL6-1 (red wire)

and/or PL6-3 (black wire). If 24 vac is not present, check wiring (see unit label

diagram).

2. Check proper thermostat connection to G on the connection board.

No power to economizer

motor.

1. Check that SW3 is properly making contact with the damper blade. Check that

SW1 is in the NC (normally closed) position.

2. Check diode D18. If diode is not functioning properly, replace circuit board.

3. Confirm that the economizer control board is grounded properly at PL6-4 (brown

wire) and at brown terminal of the economizer control board (brown wire). The

economizer motor must also be grounded properly at the negative motor terminal

(brown wire).

4. Verify SW1 and SW3 are working and wired properly (see unit label diagram).

5. Check for 24 vac input at both PL6-1 (red wire) and PL6-3 (black wire). If 24 vac

not present, check unit wiring (see unit label diagram). If 24 vac is found in both

places, check for 24 vac at the yellow terminal of the economizer control board

(yellow wire). If 24 vac power is not present, replace the economizer control board.

Economizer motor failure. If the indoor fan and economizer motor are energized, verify that there is a minimum

of 18 vdc at the positive motor terminal. If the motor is not operating, replace the

motor.

Economizer operation

limited to minimum

position.

OAT or EC set too high. 1. Set at correct temperature (3 F below indoor space temperature).

2. Check OAT or EC by setting above outdoor temperature or humidity level. If the

OAT or EC switches do not close, replace OAT or EC.

Economizer control board

incorrectly wired or not

functioning.

1. Perform the following tests when OAT or EC is closed. Y1 is called for, and damper

is at minimum position. Confirm 24 vac on gray terminal of the economizer control

board (gray wire). If 24 vac is not present, check wiring (see unit label diagram).

2. Verify that SW1 and SW3 are wired correctly and working properly (see unit label

diagram).

3. Check to ensure that 24 vac exists at PL6-2 (blue wire). If 24 vac is not present,

check wiring (see unit wiring label diagram).

4. Check 24 vac output at PL6-10 (white wire). If 24 vac is not present, replace

economizer control board.

Incorrect SAT wiring or

inoperative SAT.

1. After verifying that the OAT and EC settings and the economizer control board wir-

ing are correct, check to ensure that the 24 vac terminal of the SAT has 24 vac

(white wire). If OAT, EC, and control board are functioning and wired properly and

no 24 vac exists, check wiring (see unit label diagram).

2. If supply-air temperature is greater than 57 F, 24 vac should be found at terminal

T2 on the SAT (pink wire). If 24 vac is not present, replace SAT.

Damper does not

close.

Incorrect economizer

wiring.

1. Verify that SW2 and SW4 are wired and working properly (see unit label diagram).

2. Check diode D19. If diode is not functioning properly, replace circuit board.

Incorrect damper actuator

wiring or inoperative

economizer circuit board.

1. After verifying that the wiring is correct, modulate the damper to the minimum posi-

tion. Remove the calls for G.

2. If the damper does not move, check for 24 vac at PL6-1 (red wire). If 24 vac is not

present, check wiring (see unit label diagram).

3. If damper still does not move, check for 24 vac at blue terminal of economizer con-

trol board (blue wire). If 24 vac is not present, replace the economizer circuit board.

Incorrect SAT wiring or

inoperative SAT.

1. After verifying that the wiring is correct and the economizer control board is func-

tioning properly, place the OAT or EC switch in the closed position. Place a call for

Y1 and open the damper to the fully open position. Confirm that the 24 vac terminal

of the SAT has 24 vac (white wire). If 24 vac is not present, check wiring (see unit

label diagram).

2. If supply-air temperature is less than 52 F, 24 vac should be found at terminal T1

on the SAT (violet wire). If 24 vac not found, replace SAT.

Economizer motor failure. If economizer control board and SAT are functioning properly, verify that there is a

minimum of 18 vdc at the positive motor terminal. If a minimum of 18 vdc is present

and the motor is still not operating, replace the motor.

Economizer damper

does not close on

power loss.

Insufficient battery power,

inoperative economizer

control board.

1. Check voltage potential across batteries. If lower than 14 vdc, replace close-on-

power-loss power supply (9-v alkaline batteries). Check this emergency power sup-

ply on a regular basis or whenever the filters are changed.

2. If the close-on-power-loss and economizer control board are functioning properly,

check for 14 vdc or higher at the blue terminal of the economizer control board

(blue wire) when power is disconnected from unit. If 14 vdc is not present, replace

the control board.

C1 —

Common Power

EC —

Enthalpy Control

IFC —

Indoor Fan Contactor

IFO —

Indoor Fan On

OAT —

Outdoor-Air Temperature

PL —

Plug

SAT —

Supply-Air Thermostat

SW —

Economizer Position Switch

1 2 ... 38 39 40 41 42 43 44 45 46 47 48

Comments to this Manuals

No comments

Bryant 548F User Manual Page 43

Comments to this Manuals

Related products and manuals for Pumps Bryant 548F