Remote Sensor Troubleshooting Guide

Comfort-Set II

Comfort-Set III/Comfort-Set 90/90 Series

Single Stage Models: Verify jumper wire W-22on the back of the thermostat (not the subbase) has been clipped. Multi-stage and Heat Pump Models: Verify jumper wire W-18on the back of the thermostat (not the subbase) has been clipped.

Single Stage Models: Verify jumper wire W-922on the back of the thermostat (not the subbase) has been clipped. You must also enable the remote sensor option in the Installation Instructions, Configuration Menu.

Multi-stage and Heat Pump Models: When installing a remote sensor you must enable the remote sensor option in the Installation Instructions, Installer Menu.

Troubleshooting Chart

To function correctly and read temperature accurately, the thermostat (when set up for a remote as outlined above) must have constant 24-volt power. If the thermostat temperature is steadily dropping, reading low, or reads 08° when a remote sensor is installed, it can be traced to one of the three following conditions.

Condition	Test	Comments
1. Loss of 24-volt power.	On models with batteries, remove the batteries and re-install	For the sensor to read correctly,
	thermostat. If the display is blank, check heating and cooling	the 24-volt system power must
	system to determine why 24-volt power is absent.	be present. Some systems may
		require an isolation relay to pro-
		vide constant power to the
		thermostat. Limit or safety
		devices in the equipment can
		also cause a power interruption.

2. A broken wire on S1,	Disconnect sensor wires at thermostat. Attach a short piece	Repair or replace the 3 wire
S2 and S3 or (+, SA, -)	(2') of three-wire shielded cable to S1, S2 and S3 or (+, SA,	shielded cable. Be sure the
from the thermostat to	-) on the subbase. Bring the remote sensor to the thermostat	remote wire run is not parallel
the remote.	location and attach S1, S2 and S3 or (+, S, -) respectively.	to line voltage wires that carry
	Reattach thermostat. If the temperature begins to climb	heavy inductive loads, or across
	(slowly), it is reading correctly. If it reads correctly with the 2'	fluorescent light ballasts that
	length but improperly when attached to the wire run, it	may cause an inductance to be
	indicates a fault in the wire run.	transmitted to the thermostat.

3. A shorted or	Because it is an electronic sensor, there are no Ohm values	Replace remote sensor.
damaged remote sensor.	to test. If correct conditions as listed in 1 & 2 above and the
	temperature stays at or near 08°, it indicates a shorted or
	damaged remote sensor.

Note: Digital thermostats and remote sensors acclimate very slowly to temperature change. It may take an hour or more for the temperature to acclimate to the room temperature from a low temperature reading as outlined above. To expedite the room temperature display use the reset instructions listed in the installation instructions for the thermostat model you are working with. When reset, the thermostat will default to a room temperature of 70° and begin sensing room temperature. Be sure to reconfigure the installer menu for a remote sensor because the reset function may cancel remote sensing.