Step 2 Remove Old Thermostat - Honeywell CT3400 Instructions Manual

Acquire tools and items as needed (below).
STEP 2 Remove Old Thermostat
Test to make certain that your heating and
cooling systems are working properly. If either
does not work, contact your local heating/air
conditioning dealer. To avoid compressor dam-
age, do not operate the cooling system when
outdoor temperature is below 50 F (10 C).
Turn off power to system at the furnace, or
at the fuse/circuit breaker panel.
Carefully unpack your new thermostat and
wallplate; save package of screws, instructions
and receipt.
Remove the cover from the old thermostat. If
it does not snap off when pulled firmly from the
bottom, check for a screw used to lock on the
cover.
Loosen screws holding thermostat to sub-
base, wallplate or wall, and lift away.
CROSS-RECESSED
SCREWDRIVER
WIRE CUTTER/STRIPPER OR SHARP
KNIFE, IF NEEDED, TO STRIP WIRES
LEVEL, IF NEEDED, TO LEVEL
THERMOSTAT FOR APPEARANCE
HAND OR POWER
DRILL WITH 3/16 INCH
DRILL BIT, IF NEEDED, TO
DRILL HOLES IN WALL
MASKING TAPE, IF
NEEDED, TO LABEL WIRES
AS DISCONNECTED FROM
OLD THERMOSTAT
3
Disconnect wires from old thermostat or
subbase. As you disconnect each wire, use
masking tape to label it with the old terminal
designation. If there are
only two wires, they do
not need to be labeled.
Wrap wires around
pencil to keep them
from falling back into
the wall, as shown.
Replacing a clock thermostat that has C or
C1 clock terminals?
If you are replacing a Honeywell Chronotherm
Thermostat, you may find one or two wires that
go to the C or C1 clock terminals on the
®
Chronotherm Thermostat wiring wallplate. Do
4
M878B
69-0733—3
WIRES THROUGH
WALL OPENING
69-0733—3
M5136
®