GPG16M Service Manual

SERVICING
49
AUX. LIMIT
HIGH VOLTAGE!
Disconnect ALL power before servicing
or installing this unit. Multiple power
sources may be present. Failure to do so
may cause property damage, personal injury
or death.
1. Remove the wires from the auxiliary limit control termi-
nals.
2. Using an ohmmeter, test for continuity across the two
terminals. No reading indicates the control is open. Push
the red reset button, test again - if still open, replace the
control.
VOLT / OHM
METER
RED
RESET
BUTTON
COLOR
IDEN TIFYING
TAB
TESTING AUXILIARY LIMIT CONTROL
S-302 CHECKING FLAME ROLLOUT SWITCH
APG/GPG units are equipped with a temperature-activated
manual reset control. This control is mounted to the manifold
assembly and is wired in series with the auxiliary limit and
gas valve. The control is designed to open should a flame roll
out occur. An over firing condition or flame impingement on
the heat shield can also cause the control to open.
If the rollout control has opened, the circuit between the
ignition control and gas valve will be interrupted and the
ignition control module will go into lockout. The servicer
should reset the ignition control by opening and closing the
thermostat circuit. The servicer should look for the ignitor
glowing which indicates there is power to the ignition control.
The servicer should measure the voltage between each side
of the rollout control and ground while the ignition control is
try to power the gas valve.
VOLT / OHM
METER
RED
RESET
BUTTON
COLOR
IDENTIFYING
TAB
CHECKING FLAME ROLLOUT SWITCH
Limit Switch Operation (Applies to Primary, Auxiliary,
and Roll Out Limits) DSI systems.
If a limit switch opens, the indoor blower is energized on heat
speed and the induced draft blower is energized. The LED
on the control flashes "4" to indicate an open limit switch.
The blower and inducer remain on while the limit switch is
open. The gas valve is de-energized. Power to the thermo-
stat "R" is removed while the limit switch is open.