GM9S80 Service Manual

SERVICING
34


-

-

RED
RESET
BUTTON
COLOR
IDENTIFYING




-


A temperature activated manual reset control is mounted to
the manifold assembly on 80% furnaces.




   -

shield may also cause the control to open. If the rollout control
opens, the air circulation blower will run continuously.
On single-stage 80% the ignition control diagnostic light will

some models this also indicates an open control board fuse)


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 glowing
which indicates there is power to the ignition control. Mea-
sure 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
control and ground during the ignition attempt. Refer

RED
RESET
BUTTON
COLOR
IDENTIFYING


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 con-
trol 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
operation.