Section 18. Sequence Of Operation - Trane GAF2A0A36M31EC Installer's Manual

Section 18. Sequence of Operation

18.1 Sequence of Operation
GAF2-36M Sequence of Operation:
Abbreviations
• ER = Electronic Relay
• EVC = Expansion Valve Control
• EEV = Electronic Expansion Valve
• YI = Y signal into the EVC from the comfort control
• YO = Y signal out of the EVC from the comfort control
See unit, electric heat, and field wiring diagrams for additional
information.
Continuous Fan
IMPORTANT: If the indoor air exceeds 60% relative
humidity or simply feels uncomfortably humid, it is
recommended that the indoor fan only be used in the
AUTO mode.
1. R-G contacts close on comfort control sending 24VAC to
the G terminal on the fan ER
2. Low speed contacts close in the ER and send 24VAC on
terminal labeled "LOW'.
3. Blower motor will now run on low speed. Speed is field
selectable.
Heat Pump OD (cooling)
1. R-Y contacts close on the comfort control sending 24VAC to
Y terminal on ER and the YI (Y In) terminal on the EVC.
2. R-G contacts also close on the comfort control sending
24VAC to the G terminal on the ER. (The combination of
24VAC on terminals Y and G on the ER will close the high
speed contacts of the ER)
3. R-O contacts on the comfort control close sending 24VAC
to the O terminal on the EVC. This signals the EVC that
the unit is in cooling mode. The EVC will control the EEV
to maintain the correct superheat.
4. Normally closed contacts on the EVC will pass 24VAC to
the YO terminal providing power to the outdoor unit control
circuit
5. The blower motor will now run on high speed. Speed is field
selectable.
Heat Pump OD (heating)
1. R-Y contacts close on the comfort control sending 24VAC to
Y terminal on ER and the YI (Y In) terminal on the EVC
2. R-G contacts also close on the comfort control sending
24VAC to the G terminal on the ER. (The combination of
24VAC on terminals Y and G on the ER will close the high
speed contacts of the ER) The blower motor will now run
on high speed.
3. The combination of 24VAC on the Y terminal and zero volts
on the O terminal signals the EVC that the unit is in heat-
pump heating mode.
4. Normally closed contacts on the EVC will pass 24VAC to
the YO terminal providing power to the outdoor unit control
circuit
5. The blower motor will now run on high speed
30
Cooling OD
1. R-Y contacts close on the comfort control sending 24VAC to
Y terminal on ER and the YI (Y In) terminal on the EVC
2. R-G contacts also close on the comfort control sending
24VAC to the G terminal on the ER. (The combination of
24VAC on terminals Y and G on the ER will close the high
speed contacts of the ER)
3. R-O jumper on the low voltage terminal board sends 24VAC
to the O terminal on the EVC. This signals the EVC that
the unit is in cooling mode. The EVC will control the EEV
to maintain the correct superheat.
4. Normally closed contacts on the EVC will pass 24VAC to
the YO terminal providing power to the outdoor unit control
circuit
5. The blower motor will now run on high speed
Electric Heating
1. R-W contacts close on the comfort control sending 24VAC
to the W terminal on the ER. 24VAC is also sent to
energize the heat relay.
2. R-G contacts close on the comfort control sending 24VAC
to the G terminal on the ER. (The combination of 24VAC
on terminals W and G on the ER will close the high speed
contacts of the ER)
3. WJ contacts on the ER close providing an interlock circuit to
allow the electric heat relays to operate.
The comfort control must be setup to control R-G contacts with
a call for electric heat. This closes the interlock circuit and
allows the heat relay circuit to be energized.
Optional Condensate Switch
1. An optional OEM condensate switch can be installed within
the unit. This switch is only available through the National
Distribution Center or Global Parts.
2. Switch contacts are normally open and close when water
level rises. The closed switch will interrupt current flow to
the YO terminal and de-energize the OD unit.
3. Switch is only operational during cooling mode. Condensate
overflow is not operational during heating or defrost
modes.
Standard aftermarket condensate switches cannot be used
within the unit but can be installed exterior of the unit.
The 3rd party condensate overflow switch must be wired
between Y of the thermostat and YI of the EEV control.
Freeze Protection
1. The EVC control has the ability to sense when the coil is
beginning to ice. When this event occurs, the contacts to
the YO circuit will open and de-energize the OD unit.
2. The indoor blower motor will continue to run to aid in
defrosting the coil. After the coil has sufficiently defrosted,
the YO contacts will close and cooling operation will begin
again.