Daikin APGM3 Service And Troubleshooting page 7

SYSTEM OPERATION
Cool Mode
1. When the thermostat calls for cooling ("Y"), the control
energizes the cooling speed fan after a 7 second
on delay. The control provides a 3 minute anti-short
cycle protection for the compressor. If the compressor
has been off for 3 or more minutes, the compressor
immediately energizes when the thermostat calls for
cool. If the compressor has not been off for at least
3 minutes when a call for cool occurs, the control
waits until 3 minutes has elapsed from the time
the compressor was last de-energized before re-
energizing the compressor.
2. When the thermostat removes the call for cooling
("Y") the compressor is de-energized and the control
de-energizes the cooling speed fan after a cooling off
delay period of 60 seconds.
NOTE: A call for cooling has priority over continuous
fan. If G is energized while Y is energized, during the
cooling fan on delay, the fan will remain off until the
delay is over.
NOTE: The cooling fan operation will continue to
function while the control is in heat lockout.
NOTE: If a call for heat exist with a call for cooling, the
call for heat shall proceed as normal except the fan
remains energized on cool speed.
Heat Mode
1. CALL FOR HEAT - The thermostat calls for heat by
energizing the "W" terminal. The control checks to see
if the pressure switch is open. If the pressure switch
is closed, the control will flash code "3" on the LED
and wait indefinitely for the pressure switch to open.
The control will lockout the call for heat if the pressure
switch is closed before the induced draft motor is
energized.
2. PRE-PURGE - The control energizes the induced
draft motor, flashes code "2" on LED, and waits for
the pressure switch to close. When the pressure
switch has closed, the control stops flashing the LED
and begins timing the 15 second pre-purge period.
(NOTE: Under normal operation, the LED will not
flash if the pressure switch closes immediately after
energizing the induced draft motor.)
3. IGNITION - The control energizes the gas valve and
spark. If flame is not established within 7 seconds,
the gas valve and spark are de-energized and the
control goes to an inter-purge. If flame is established,
the spark is de-energized and the control goes to heat
blower on delay.
4. Heat Blower On Delay - The control waits for 30
second heat fan on delay and then energizes the
indoor blower heat speed. If the blower is already
energized by a call for cooling or continuous fan, or in
a blower off delay period, the on delay is skipped and
control goes to steady heat.
5. STEADY HEAT - Control inputs are continuously
monitored to ensure limit and pressure switches are
closed, flame is established, and the thermostat call
for heat remains.
6. POST PURGE - When the thermostat demand for
heat is satisfied, the control immediately de-energizes
the gas valve. The inducer output remains on for a 29
second post-purge period.
7. Heat Blower Off Delay - The indoor blower motor is
de-energized after the selected blower off delay time.
Blower timing begins when the thermostat is satisfied.
L2 L2 L2 L2
L1 D1
COOL HEAT L1
UNUSED
Pin Voltage
1 24VAC 24VAC Input (from Transformer)
2 24VAC 24VAC Common (Chassis Ground)
3 24VAC Gas Valve Output
4 24VAC Limit Switch Output
5 24VAC Limit Switch Input (Common with Pin 9)
6 24VAC Pressure Switch Input
7 24VAC Thermostat Fan (G) Input
8 24VAC Pressure Switch Output (Common with Pin 10)
9 24VAC Thermostat "R" (Common with Pin 5)
10 24VAC Thermostat Heat Input (W) (Common with Pin 8)
11 24VAC Thermostat Cool Input (Y)
12 24VAC Compressor Contactor Output
Table 1: PCBAG123 Single Stage Control Circuit
Definitions for 12-Circuit Connector
Blower Off Delay Settings
1
3 2
6 5 4
9 8 7
FS
12 10
11
Transformer
Function
speed up
7