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Sherri BrownAug 13, 2025
What does ROOM mean on McQuay Thermostat display?
- CCarol MartinezAug 13, 2025
If your McQuay Thermostat displays 'ROOM', it means the room temperature offset is not zero.
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If your McQuay Thermostat displays 'ROOM', it means the room temperature offset is not zero.
How to fix incorrect room temperature on McQuay Thermostat?
To correct the room temperature reading on your McQuay Thermostat, ensure the wall hole behind the thermostat is plugged with putty or insulation. You can also calibrate the thermostat.
Why does my McQuay LIA266 fan run continuously?
If the fan runs continuously on your McQuay Thermostat, check the fan On/Auto switch. If it's in the ON position, the indoor fan will run continuously.
What to do if McQuay Thermostat turns on and off too frequently?
To address frequent on/off cycling of your McQuay Thermostat, adjust the temperature differential.
How to troubleshoot McQuay Thermostat with no display?
If your McQuay Thermostat has no display, check for 24 VAC/VDC at the thermostat. The display will be blank if 24 VAC/VDC is not present.
Why is my McQuay Thermostat system fan not working properly?
If the system fan on your McQuay Thermostat isn't working correctly, verify the wiring and check the configuration.
What does 'Er' mean on my McQuay LIA266?
If your McQuay Thermostat displays 'Er', it indicates a sensor error. Check the S1 & S2 connections, inspect the remote sensor wire and connections, and ensure you are using shielded wire for the remote sensor.
What to do if my McQuay LIA266 Thermostat has an unlisted problem?
If you're experiencing an unlisted problem with your McQuay Thermostat, press the Reset button once. This will refresh the display and reset the anti-short cycle timing to zero.
Wiring diagram for McQuay single circuit board.
Wiring diagram for McQuay dual circuit board.
Details the various settings available in configuration mode.
Wiring diagram for McQuay single circuit board.
Wiring diagram for McQuay dual circuit board.
Details the various settings available in configuration mode.
The McQuay Auto-changeover Electronic Thermostat (Part No. 668375401, LIA266) is a sophisticated control device designed for 2-stage heat and 2-stage cool systems. This hardwired thermostat offers both auto and manual changeover capabilities, making it versatile for various HVAC applications, particularly McQuay WSHP (Water Source Heat Pump) units.
The thermostat's primary function is to regulate room temperature by controlling heating and cooling systems. It operates as a two-stage heat, two-stage cool thermostat, activating the first stage of heating when the room temperature falls below the heat set temperature (by a configurable differential) and the second stage if the temperature continues to drop. Similarly, for cooling, it activates the first stage when the room temperature exceeds the cool set temperature (by a configurable differential) and the second stage if the temperature continues to rise. The heat and cool outputs can be configured to stage off independently or simultaneously.
It supports multiple operating modes:
The indoor fan can be manually activated in any operating mode using the Fan switch (Auto/On).
The McQuay Auto-changeover Electronic Thermostat is designed for reliable and precise temperature control in commercial and industrial HVAC systems, offering flexibility through its configurable settings and user-friendly interface.
General| Brand | McQuay |
|---|---|
| Model | LIA266 |
| Category | Thermostat |
| Language | English |
