Duty Cycle; Maintenance; Fuse On Powered Type; Commerical Defrost Control - Bryant Preferred 549K 04-06 Service And Maintenance Instructions

Duty Cycle

The unit-powered convenience outlet has a duty cycle limita-
tion. The transformer is intended to provide power on an inter-
mittent basis for service tools, lamps, etc; it is not intended to
provide 15A loading for continuous duty loads (such as electric
heaters for overnight use). Observe a 50% limit on circuit load-
ing above 8A (i.e., limit loads exceeding 8A to 30 minutes of
operation every hour).

Maintenance

Periodically test the GFCI receptacle by pressing the TEST
button on the face of the receptacle. This should cause the in-
ternal circuit of the receptacle to trip and open the receptacle.
Check for proper grounding wires and power line phasing if
the GFCI receptacle does not trip as required. Press the RESET
button to clear the tripped condition.

Fuse on Powered Type

The factory fuse is a Bussmann Fusetron
screw-in (Edison base) type plug fuse.
USING UNIT-MOUNTED CONVENIENCE OUTLETS
Units with unit-mounted convenience outlet circuits will often
require that two disconnects be opened to de-energize all pow-
er to the unit. Treat all units as electrically energized until the
convenience outlet power is also checked and de-energization
is confirmed. Observe National Electrical Code Article 210,
Branch Circuits, for use of convenience outlets.
1. Bussmann and Fusetron are trademarks of Cooper Technologies
Company.
Fig. 30 — Defrost Control Board Location - 549K 04-06 Electro-Mechanical Units
T-15, non-renewable
1
18

COMMERICAL DEFROST CONTROL

On 549K units equipped with electro-mechanical controls or the
optional factory-installed RTU Open controller the Defrost Con-
trol Board (DFB) coordinates thermostat demands for supply fan
control, 1 or 2 stage cooling, 2 stage heating, emergency heating
and defrost control with unit operating sequences. The DFB also
provides an indoor fan off delay feature (user selectable). See
Fig. 29 for board arrangement.
The DFB is located in the main control box of the 549K unit (see
Fig. 30). All connections are factory-made through harnesses to
the UCB (unit control board) to the ECM (direct-drive motor), re-
versing valve solenoids and to defrost thermostats. Refer to
Table 7 for details of DFB Inputs and Outputs.
Fig. 29 — Defrost Control Board Arrangement
DIP
SWITCHES
SPEED-UP
JUMPERS