Electric Heat Only Sequence - 24Vac Input; Heat Pump Only Sequence - 24Vac Input; Heat Pump With Electric Heat Sequence - 24Vac Inputs; Test Mode - Trane ACONT900AC43UA Service Manual

Electric Heat Only Sequence – 24VAC Input
• When the W1 and G are present, the control will
energize the 1st heater contactor and blower at the
heating speed selected via the User Interface. (G is
not required)
• When W2 is present, the control will energize the
2nd stage heater contactor.
• When W3 is present, the control will energize the
3rd stage heater contactors.
• When W1, W2 or W3 is removed, the corresponding
contactor will de-energize.
Heat Pump Only Sequence – 24VAC Input
• When Y1 and G are present, the compressor will be
energized along with the blower on high speed in single-
stage operation or low speed in two-stage operation.
• When Y1 and Y2 are present, the 2nd stage
compressor (in two-stage equipment) will energize and
the blower will go to high speed (Air handler must be
set for 2 stage operation).
• When Y2 and Y1 inputs are removed, the 2nd stage
compressor will turn off. When G is removed, the
corresponding compressor stage will cycle off after
the Heat-Off-Delay (selectable) has timed out.
Heat Pump with Electric Heat Sequence
– 24VAC Inputs
• When Y1 and G are present, the compressor will
energize along with the blower on high speed in single-
stage operation or low speed in two-stage operation.
• When Y1 and Y2 are present, the 2nd stage
compressor (in two-stage equipment) will energize and
the blower will go to high speed.
• When any combination W1, W2, and W3 are present
the air handler control will energize appropriate heater
contactor.
• If the cooling CFM is lower than the selected heating
CFM, the motor will run in the heating speed (Air handler
will select highest CFM).
• When any W input is removed, the corresponding
Air Handler
Heat output will be de-energized.
• When Y1 and Y2 inputs are removed, the 2nd stage
compressor will turn off. When G is removed, the
corresponding compressor stage will cycle off after
the Heat-Off-Delay (selectable) has timed out.

Test Mode

The Comfort Control should be switched to "OFF" before
entering the Unit Test Mode via the User Interface. The
Test mode operates the same in Communicating Mode
and 24 Volt Mode.
Note: Unit will exit Test Mode if any one of the
following conditions exists:
• If Air Handler receives a request for operation from
the Comfort Control. (This includes Heating, Cooling
or Blower requests).
• If a fault is detected during any phase of Test Mode
(except 123).
• If any button on the User Interface is pressed.
To access the Unit Test Mode scroll down through the
User Interface Information Menu until you see the Unit
Test option. Press ENTER. When prompted select
YES and press ENTER. When the User Interface
displays ARE YOU SURE? Select YES and press
ENTER to begin the Unit Test.
The Unit Test will perform the following steps
without delays:
(User Interface displays UNIT TEST – BLWR)
• Start Blower at 50% airflow for 10 seconds
• Go to 100% airflow for 10 seconds
(User Interface displays UNIT TEST – COOL)
• Energize Y1 relay for 15 seconds with 100% airflow
• De-energize Y1 relay and go to Electric Heat airflow
(User Interface displays UNIT TEST – HEAT)
• Energize blower interlock and stage 1 heat relay
AH - A 7