GSZH5 Service Manual
88
SERVICING
9. Remove the bolts holding the motor bracket to the
blower and slide out of blower shell.
10. Replace the motor and reinstall blower and control box.
11. Reconnect power and test operation.
The MBR/AR*F contains an Electronic Blower Time Delay
delays for the blower motor in cooling and heat pump
heating demands when “G” is energized.
During a cooling or heat pump heating demand, 24Vac is
supplied to terminal “G” of the EBTDR to turn on the blower
motor. The EBTDR initiates a 7 second delay on and then
energizes it’s onboard relay. The relay on the EBTDR
board closes it’s normally open contacts and supplies
power to the blower motor. When the “G” input is removed,
seconds delay expires the onboard relay is de-energized
and it’s contacts open and remove power from the blower
motor.
During an electric heat only demand, “W1” is energized but
“G” is not. The blower motor is connected to the normally
closed contacts of the relay on the EBTDR board. The
other side of this set of contacts is connected to the heat
sequencer on the heater assembly that provides power
sequencer will close it’s contacts within 10 to 20 seconds to
motor through the normally closed contacts on the relay
on the EBTDR. When the “W1” demand is removed, the
sequencer opens it contacts within 30 to 70 seconds and
removes power from the heater element and the blower
motor.
The EBTDR also contains a speedup terminal to reduce
the delays during troubleshooting of the unit. When this
terminal is shorted to the common terminal, “C”, on the
EBTDR board, the delay ON time is reduced to 3 seconds
and the delay OFF time is reduced to 5 second.
Two additional terminals, M1 and M2, are on the EBTDR
board. These terminals are used to connect the unused
board’s operation.
WARNING
If the compressor terminal PROTECTIVE COVER and
gasket (if required) are not properly in place and secured,
there is a remote possibility if a terminal vents, that the
vaporous and liquid discharge can be ignited, spouting
injury to anyone in its path.
This discharge can be ignited external to the compressor
if the terminal cover is not properly in place and if the
Ignition of the discharge can also occur at the venting
contaminant air present in the system and an electrical arc
occurs as the terminal vents.