3
REPLACEMENT INSTALLATION
REMOVE OLD THERMOSTAT
1.
Shut off electricity at the main fuse box until installa-
tion is complete. Verify power is off with a voltmeter.
2.
Remove the front cover of the old thermostat. With
wires still attached, remove wall plate from the wall.
3.
If the old thermostat has a wall mounting plate,
remove the thermostat and the wall mounting plate as
an assembly.
4.
Use the Cross Reference Guide to find the thermostat
type you are replacing.
5.
Identify each wire attached to the old thermostat
using the labels enclosed with the new thermo-
stat. Record the identification of the wire on the
corresponding blank in Table 2.
6.
Disconnect the wires from old thermostat one at a
time. Pull at least 6 inches of wire out of the wall. DO
NOT LET WIRES FALL BACK INTO THE WALL.
7.
Install new thermostat using the following proce-
dures.
ATTACH SUBBASE TO WALL
1.
Remove the packing material from the thermostat.
Place the fingers of one hand on the center top and
bottom portion of the thermostat. Grasp the subbase
in the other hand on the top and bottom center, and
gently pull straight out (see fig. 2). The thermostat has
pin and socket connectors. Forcing or prying on the
thermostat will cause damage to the unit.
THIS THERMOSTAT REQUIRES BOTH THE HOT AND
COMMON SIDES OF THE 24 VAC TRANSFORMER TO
BE PRESENT TO THE THERMOSTAT FOR OPERA-
TION.
NOTE
TABLE 2. TERMINAL REFERENCE
LABEL
NUMBER
1F91-71
TERMINAL
DESIGNATION
FUNCTION
OLD THERMOSTAT
TERMINAL
DESIGNATION
G
C
—
R
O
B
—
—
Y1
Y2
W1
W2
W3
Fan output
Transformer 24 VAC common
—
Transformer 24 VAC hot
Changeover output (cool)
Changeover output (heat)
—
—
Stage 1 cool
Stage 2 cool
Stage 1 heat
Stage 2 heat
Stage 3 heat
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
PULL STRAIGHT OUT
Figure 2. Removing thermostat from subbase
TABLE 1. WIRE IDENTIFICATION LABELS
1
G
G
1
9
Y1
Y1
9
2
C
C
2
3
L
L
3
4
R
R
4
5
O
O
5
6
B
B
6
7
E1
E1
7
8
E2
E2
8
10
Y2
Y2
10
11
W1
W1
11
12
W2
W2
12
13
W3
W3
13
14
S1
S1
14
15
S2
S2
15
16
S3
S3
16