
SERVICING
61
Rev. 0
4. After completing check and/or replacement of primary
limit control, reinstall burner compartment door.
5. Turn on electrical power and verify proper unit opera-
tion
To aid in identifying these controls, these controls have a
color coded marking on them. Refer to the following chart
for temperature settings and color codes.
Part Number
01
02
03
04
05
06
07
Open Setting
210
220
160
150
145
170
155
Color Code(s)
Red
Green
Blue
Brown
Yellow
White
Orange
GUCA045AX30
1
GUCA070AX30
1
GUCA070AX40
1
GUCA090AX40
1
GUCA090AX50
1
GUCA115AX50
1
GCCA045AX30
1
GCCA070AX30
1
GCCA070AX40
1
GCCA090AX40
1
GCCA090AX50
1
GCCA115AX50
1
T.O.D. PRIMARY LIMIT (201629__)
S-6 CHECKING AUXILIARY LIMIT CONTROL
Both the GUCA and GCCA furnaces use an additional limit
switch required for safety control of high temperature within
the furnace or duct work.
This control is preset, nonadjustable manual reset, control
mounted in the blower compartment area. The auxiliary limit
control is mounted on the blower deck of the GUCA, and
on the blower housing of the GCCA.
It is connected in series with the primary limit control wiring
to the integrated ignition control. If its temperature should
be exceeded, it will open, interrupting the voltage to the
gas valve causing it to close.
WARNING
Disconnect Electrical Power Supply:
1. Remove blower compartment door to gain access to
the auxiliary limit control located in the furnace blower
compartment area.
2. Remove the wires from the auxiliary limit control termi-
nals.
3. Use an ohmmeter, test for continuity across the two
terminals (see auxiliary limit control figure below). No
reading indicates the control is open. Push the red re-
set button, test again - if still open, replace the control.
Color
Identifing
Tab
Red
Reset
Button
VOLT / OHM
METER
Testing Auxiliary Limit Control
To aid in identifying these controls, color coded labels are
attached to the back of the controls. Refer to the chart be-
low for temperature settings, color codes and the number
of controls used on each unit.
Part Number
06
16
18
19
Open Setting (°F)
160
150
170
160
Color Code(s)
Orange
Red
Blue
Pink
GUCA045AX30
1
GUCA070AX30
1
GUCA070AX40
1
GUCA090AX40
1
GUCA090AX50
1
GUCA115AX50
1
GCCA045AX30
2
GCCA070AX30
2
GCCA070AX40
2
GCCA090AX40
2
GCCA090AX50
2
GCCA115AX50
2
AUXILLARY LIMIT SWITCHES (101235__)
4. After completing check and/or repair of auxiliary limit
control, reinstall blower access door.
5. Reapply power and verify proper operation of the fur-
nace.
S-7 CHECKING BLOWER MOTOR
WARNING
Disconnect Electrical Power Supply:
1. Remove blower compartment door to gain access to
the circulator blower motor.
2. Disconnect the motor wire leads from its connection
point at integrated control module and capacitor if ap-
plicable.
3. Using an ohmmeter, test for continuity between each of
the motor leads.
4. Touch one probe of the ohmmeter to the motor frame
(ground) and the other probe in turn to each lead.