Lennox VRF VMDB Series Installation Instruction page 19

Relocate T1 Return Air Sensing
Relocate the unit return air sensing from inside the unit
to a location within the conditioned zone whenever the
return is pulling air from above the ceiling or if fresh air is
being introduced and mixed into the return. The T1 sen-
sor cannot accurately read the space temperature under
these conditions if the sensing remains located inside of
the unit.
Two methods of relocating the return air sensing are:
1. Set return air sensing to the wired local controller. See
the specific controller's installation and user manual
for instructions.
2. Relocate physical T1 sensor. Instructions below.
Relocate Physical T1 Sensor Instructions
This sensor can be extended with 18 AWG stranded
shielded cable.
1. Identify the T1 connection on the main board - CN4.
(white wires soldered to PCB)
Figure 26. Identify T1 Sensor Connection on PCB
2. Identify where the white wire is plugged into the black
wire.
Figure 27. Identify White Plug into Black Wire
3. Cut the black wire between the plug and the sensor
thermistor. Leave adequate room for making wiring
connections on each end.
Figure 28. Cut the Black Wire
4. Prepare the 18 AWG stranded shielded extension
cable.
5. Solder the extension cable to the black wire on each
end or use the VRF accessory V0SNSR00P to splice
in the extension cable.
6. Locate the return air thermistor to the conditioned
area of which the indoor unit serves.
Figure 29. Sensor Thermistor
Avoid installing sensor in high load or heat loss areas
such as exterior walls or walls that are against uncondi-
tioned spaces, near entry doors and windows, or where
direct sunlight may be present.
19
IMPORTANT