SERVICING
117
To aid in identifying these controls, color coded labels are
attached to the back of the controls. Refer to the Auxiliary
Limit Charts in furnace Technical Manual for color codes
and temperature settings.
S-302 CHECKING FLAME ROLLOUT CONTROL
A temperature activated manual reset control is mounted to
the manifold assembly on 80% & 90% furnaces, as shown
in the following illustrations.
ROLLOUT
SWITCH
Flame Rollout Switch Location
(80% Upflow Furnace Shown, Downflow Similar)
*
*
*
**
*
*
2
FLAME
ROLLOUT
SWITCHES
Flame Rollout Switch Location
(90% Upflow Furnace Shown, Counterflow Similar)
The control is designed to open should a flame roll out oc-
cur. An over firing condition or flame impingement on the
heat shield may also cause the control to open. If the rollout
control opens, the air circulation blower will run continu-
ously.
On single-stage 80% and 90% models, the ignition control
diagnostic light will flash (6) six times indicating a trip of the
rollout switch.
On two-stage 80% and 90% models the ignition control the
diagnostic light will flash (4) four times indicating a trip of the
rollout switch. These symptoms are identical to a trip of the
primary limit control.
To aid in identifying these controls, color coded labels have
been affixed to the back of these controls. Refer to the Rollout
Limit Charts in furnace Technical Manual for temperature set-
tings and color codes.
The circuit between the ignition control and gas valve will be
interrupted when the rollout switch opens up.
LINE VOLTAGE NOW PRESENT
WARNING
1. Remove the burner compartment door to gain access to
the rollout switch(es) mounted to burner bracket.
The servicer should reset the ignition control by opening and
closing the thermostat circuit. Then look for the ignitor glow-
ing which indicates there is power to the ignition control.
Measure the voltage between each side of the rollout control
and ground while the ignition control tries to power the gas
valve.
2. Measure the voltage between each side of the rollout con-
trol and ground during the ignition attempt. Refer to the
following figure.
VOLT / OHM
METER
GN
D
RED
RESET
BUTTON
COLOR
IDENTIFYING
TAB
Checking Flame Rollout Switch
( 80% & 90% Furnaces )
a. If no voltage is measured on either side of control it
indicates ignition control or wiring to control problem.
b. If voltage is measured on one side of the control and
not the other it indicates the control is open.
c. If voltage is measured on both sides of the control the
wiring to gas valve or valve is at fault.
3. After check and/or replacement of rollout switch, rein-
stall burner compartment door and verify proper unit op-
eration.
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