Table of Contents
Advertisement
TROUBLESHOOTING
Primary Limit
A primary limit will open due to excessive supply air
temperatures. This can be caused by a dirty filter,
excessive duct static, insufficient air flow, or a faulty limit.
Check filters, total external duct static, blower motor, blower
motor speed tap (see wiring diagram), and limit. This limit
will automatically reset once the temperature falls below a
preset level.
If a limit switch opens, the gas valve is immediately de-
energized, the induced draft and air circulating blowers
are energized. The induced draft and air circulator blowers
remain energized for 5 minutes or until the limit switch re-
closes, whichever happens first.
NOTE: If the primary limit opens three (3) times within
the same call for heat, the ignition control will lock
out for one (1) hour with the air circulating blower
energized at high heat speed.
Flame Detected with Gas Valve Closed
If flame is detected with the gas valve de-energized, the
combustion and air circulator blowers are energized. The
control can be reset by removing the power supply to the
unit or it will automatically reset after one hour. Miswiring is
the probable cause for this fault. The initial lockout period is
5 minutes. After that time, the control continues to monitor
the flame sense input and resumes normal operation when
flame is no longer sensed.
Low Flame Signal
Under some conditions, the fuel or air supply can create a
nearly invisible coating on the flame sensor. This coating
acts as an insulator causing a drop in the flame signal. If
the flame signal drops below a predetermined value, the
ignition control will display an error code of (1) flash on the
amber diagnostic LED. The unit will continue to operate
until the control can no longer detect flame.
Burner Temperature Switch
The burner temperature switch is mounted on the burner
box assembly to monitor the burner box temperature. It is
normally closed (electrically), auto-reset switch. This switch
guards against the burner flames not being properly drawn
into the heat exchanger.
The control senses an open blocked burner switch,
indicating that the burner temperature/pressure has
exceeded its set point. The control de-energizes the gas
valve, energizes the inducer to the pre-purge setting and
energizes the indoor blower. The initial lockout period is
five minutes. After this time elapses, the control evaluates
the state of the blocked burner switch. If the switch is
closed, the control resumes normal operation. The control
will enter a one hour lockout state if the blocked burner
switch fails to reset before the recovery timer has expired.
ID Plug
The control operational parameters are stored in ID Plug
which connects on the circuit board. The control requires a
valid ID plug present to operate in heating mode. If a valid
ID plug is not present the control will not respond to a call
for heat. However, the control will respond to thermostat
inputs "Y" or "G", operating the appropriate fan output.
The cooling delays are ignored in this operating mode.
The control puts the burner into hard lockout and will not
respond to heating requests until the power is cycled with a
valid ID plug installed.
Abnormal Operation - Cooling
Short Cycle Compressor Delay
In the event of intermittent power losses or intermittent
thermostat operation, the control system will delay output
to the compressor contactor for three minutes from the time
power is restored or thermostat call for cooling is restored.
(Compressor is off a total of three minutes).
NOTE: Some electronic thermostats also have a built-
in compressor short cycle timer that may be longer
than the three minute delay given above. If you are
using an electronic thermostat and the compressor
has not started after three minutes, wait an additional
five minutes to allow the thermostat to complete its
short cycle delay time.
High Pressure Switch/Low Pressure Switch
Some models include a high pressure cutout switch and/
or a low pressure switch. The high pressure cutout switch
protects the refrigeration system from excessive operating
pressures. The low pressure switch protects the refriger-
ation system from very low operating pressures due to a
loss of refrigerant. Compressor operation will be disabled if
either of these devices opens.
40
Advertisement
Table of Contents
