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Wiring Diagram

Configuration Mode

The configuration mode is used to set the McQuay 668811101 thermostat to match your heating/cooling system. 

The McQuay 668811101 thermostat functions with heat pump, air conditioning, gas, oil or electric heat systems.

1.  To enter the configuration mode, simultaneously hold down the   and   buttons while 

the McQuay 668811101 thermostat is in OFF mode.

2.  Press the   or   button to change settings within each screen.
3.  Press the 

PROG button to advance to the next screen.

 

 

Note: The MODE button will return you to the previous screen.

4.  To exit configuration mode, hold the 

PROG button for 6 seconds.

2.  Differential (1°F - 5°F) (1°C - 3°C) – Set the number of degrees between your “turn on” 

temperature and your “setpoint” temperature.

  Press the   or   button to set differential value.
  Press the 

PROG button to advance to the next screen.

3.  Deadband (1°F - 9°F) (1°C - 5°C) – Set the minimum number of degrees between 

your heating system activation and your cooling system activation.

  Press the   or   button to set deadband value.
  Press the 

PROG button to advance to the next screen

1.  Temperature scale (F or C) – Choose Fahrenheit or Celsius.
  Press the   or   button to select.
  Press the 

PROG button to advance to the next screen.

Configuration Mode Settings

4.  Heat pump – Press the   or   button to configure as heat pump, or non-heat pump 

system.

  • ON = Heat pump system – 4 minute time delay with heat and cool
  • OFF = Non-heat pump system – 4 minute time delay with cool only
  Press the 

PROG button to advance to the next screen

5.  Lockout (0-8°, NITE, COOL-HEAT) – Select the number of degrees set temperature 

can be changed during keypad lockout or select to lockout during NITE period only. 

COOL-HEAT lockout allows adjustment of the set temperatures to the maximum heat set 

temperature selected in Step 6 and minimum cool set temperature selected in Step 7.

 

  

Note: The mode cannot be changed when the thermostat is locked.

  Press the   or   button to select.
  Press the 

PROG button to advance to the next screen

6.  Maximum Heat Setpoint (45°F - 90°F) (7°C - 32°C) 
  Adjust to control the maximum heat set temperature allowed.
  Press the   or   button to select.
  Press the 

PROG button to advance to the next screen

7.  Minimum Cool Setpoint (45°F - 90°F) (7°C - 32°C) 
  Adjust to control the minimum cool set temperature allowed.
  Press the   or   button to select.
  Press the 

PROG button to advance to the next screen

ON

Starting the Thermostat

8.  Room temperature offset (+9°F to - 9°F) (+5°C to -5°C).
  Adjust to calibrate displayed room temperature to match actual room temperature.
  Press the 

PROG button to advance to the next screen.

9.  Maximum compressor cycles allowed per hour (d, 2-6). 
    – – = as many as needed, 2-6 = maximum cycles/hour
  Press the 

PROG button to advance to the next screen.

10.  Status indicator light (ON, OFF). 
 

Press the   or   button to select.

 

To exit configuration mode, press the 

PROG button for 6 seconds.

 

Note:  First button press activates backlight only.

1.  Move the Fan Auto/On switch to the Auto position.
2.  Press the 

MODE button to enter desired operating mode.

3.  Press 

PROG to select program or non-program option.

Testing the Thermostat

Once the thermostat is installed, it should be thoroughly tested.

Cool Test

1.  Press mode button until cool mode is displayed. 
2.  Adjust set temperature so it is 5 degrees below room temperature.
3.  Air conditioning should come on. Green LED turns ON.
4.  Adjust the set temperature 2 degrees above the room temperature and the A/C should 

turn off. There may be a fan delay on your system.

 

 

Note: There is a four-minute time delay to protect the compressor after it turns off.  

Heat Test

1.  Press mode button until heat mode is displayed.
2.  Adjust the set temperature so it is 5 degrees above the room temperature.
3.  Heat should come on. Red LED turns ON.
4.  Adjust the set temperature 2 degrees below the room temperature and the heat 

should turn off. There may be a fan delay on your system.

 

 

Note: For heat pumps, there is a four-minute delay to protect your compressor.

Fan Test

1.  Slide fan switch to ON position. 

Indoor fan turns ON.

2.  Slide fan switch to Auto position. 

Indoor fan turns OFF.

Mode of Operation

The McQuay 668811101 thermostat is a programmable, auto changeover, single stage heat, single stage cool 

thermostat.  It functions with air conditioning, heat pumps, gas, oil or electric heat systems. 

The thermostat activates the heating appliance when the room temperature is below the set heat temperature 

(by the differential temperature) and the red indicator light on the thermostat will light. The McQuay 668811101 

thermostat will stop outputting and the red light will turn off when the call for heat has been satisfied. With heat 

pumps, the thermostat will not let the compressor come on for 4 minutes after it turns off. This protects your 

compressor.

When the room temperature is greater than the set cool temperature (by the differential temperature), the cooling 

device is activated and the green indicator light on the thermostat will turn on. The McQuay 668811101 thermostat 

will stop outputting and the green light will turn off when the call for cooling is satisfied. The thermostat will not let the 

compressor come on for 4 minutes after it turns off. This protects your compressor.

The McQuay 668811101 thermostat has five possible operating modes: OFF, Heat, Cool, Heat & Cool and Program 

mode. In off mode, the thermostat will not turn on heating or cooling devices. The manual fan can be turned on in 

all operating modes using the fan switch and the fan speed can be set in all operating modes using the fan speed 

switch. In heat mode, the thermostat controls the heating system. In the Cool mode, the thermostat controls the 

cooling system. In heat & cool mode, the thermostat controls both the heating and cooling systems. In program 

mode, the thermostat will automatically be controlled by the set program. Program mode can function with heat 

mode, cool mode or heat & cool mode. The clock display alternates with the set temperature display for heat & cool 

mode.

The program schedule can be overridden by changing the set temperature (  or   button). This puts the McQuay 

668811101 thermostat thermostat into a 2 hour temporary hold. After 2 hours, it will automatically return to the 

program schedule.

The McQuay 668811101 thermostat also has a button lockout feature. This enables the thermostat to be set to the 

proper mode and temperature and locked so it cannot be tampered with.

Setting the Time and Day of the Week

The time and day of the week must be set for your program schedule to operate correctly.

1.  Press  the 

MODE button until you are in the OFF mode.

2.  Press  the 

PROG button in for 6 seconds. Time displays.

3.  Press the   or   button to adjust the time.

4.  Press the 

PROG button while the time is displayed. The display shows the day 

currently set on the thermostat (1=Monday, 2=Tuesday, etc).

5.  Press the   or   button to set the correct day of the week that today is.
 

  

Note: Press the PROG button in for 5 seconds to lock values into memory 

and return to the OFF mode or press the 

PROG button once to 

enter programming.  

  • Set time is displayed
8.  Press the   or   button to change set time. 
9.  Press the 

PROG button to advance to the next screen.

 

 

Note: Transitions required after 11:59 PM must be programmed in the next day’s 

MORN transition.

 

• Heat temperature is displayed (45°F to 90°F)

 

10.  Press the   or   button to adjust heat set temperature. 
11.  Press the 

PROG button to advance to the next screen.

 

• Cool temperature is displayed (45°F to 90°F)

 

 

 

Note: Cool cannot be set lower than heat temperature.

12.  Press the   or   button to adjust cool set temperature.
13.  Press the 

PROG button to advance to the next screen.

Repeat steps 1-13 to program each day of the week individually or use the Simpleset

®

 

feature (see Page 14) to program every day the same as Monday.

When programming is complete, press and hold the 

PROG button in for 5 seconds to return to the OFF mode.

PROG must display on the screen for the thermostat to follow the program schedule. If PROG does not appear, 

press the PROG button until PROG displays. 

Programming

Program Overview

The McQuay 668811101 thermostat programmable thermostat has four periods (MORN, DAY, EVE, NITE) that are 

customizable for each day of the week. Each period will have a start time, heat temperature, and cool temperature. 

The McQuay 668811101 thermostat monitors the day and time, while maintaining the specific conditions you have 

chosen for each period in your program.

1.  Press the 

MODE button until you are in the OFF mode.

2.  Press the 

PROG button for 6 seconds.

3.  Press the 

PROG button twice.

• Day is displayed (1-7) 
4.  Press the   or   button to change the day you want to program 

(1=Monday, 2=Tuesday, etc.).

5.  Press the 

PROG button to advance to the next screen.

 

  

Note:  You can always press the MODE button to return to the 

previous parameter.

• Period is displayed (MORN, DAY, EVE, NITE)

6.  Press the   or   button to change period of day. 
7.  Press the 

PROG button to advance to the next screen.

6-Wire,

MORN

DAY

EVE

NITE

HEAT

HEAT

HEAT

HEAT

COOL

COOL

COOL

COOL

MONDAY

1

MORN

DAY

EVE

NITE

HEAT

HEAT

HEAT

HEAT

COOL

COOL

COOL

COOL

TUESDAY

2

MORN

DAY

EVE

NITE

HEAT

HEAT

HEAT

HEAT

COOL

COOL

COOL

COOL

WEDNESDAY

3

MORN

6:00 AM

DAY

8:00 AM

EVE

6:00 PM

NITE

10:00 PM

HEAT

70°F

HEAT

62°F

HEAT

70°F

HEAT

62°F

COOL

78°F

COOL

85°F

COOL

78°F

COOL

82°F

MONDAY

thru

SUNDAY

Personal Program Schedule

Factory Preprogramming

The McQuay 668811101 thermostat comes preprogrammed with the following schedule:

Use the following personal program schedule to record your settings:

Simpleset® Programming

Lockout Function

After the complete Monday schedule is set (see Programming on Page 12), you are at the Day 2 screen:
1.  Press the   button once. Day 1 screen displays.
2.  Press and hold the   button for 3 seconds.

•  The days of the week will count down from 7 to 1 and this will lock the  

settings into memory.

•  Once the schedule is locked in, you can go through each day and make  

any changes you require. This feature speeds up the programming of  

the standard weekday/weekend schedule.

3.  Press and hold the 

PROG button for 5 seconds to exit program mode and return to the OFF mode.

The McQuay 668811101 thermostat thermostat has a button lockout feature so the settings cannot be 

changed or tampered with. With the lockout activated, any button press will result in “LOC” being displayed.
To activate the LOC function:
1.  Press the 

MODE button and hold it in.

2.  Also press the 

PROG button and keep both depressed for 10 seconds.

3.  LOC will display and all buttons will be disabled.
To deactivate the LOC feature, repeat steps 1 & 2 above.

Simpleset

®

 programming is a convenient method of programming the thermostat. Once the entire Monday (Day 1) 

schedule is set, Simpleset

®

 programming will copy the Monday schedule to every day of the week.

Operating Modes

There are six possible operating modes for the McQuay 668811101 thermostat. Off, Cool, Heat, and Cool & Heat 
modes are accessed by pressing the Mode button. Program mode is accessed by pressing the Prog button. Continuous 
fan mode is accessed by setting the auto/on switch to ON.

Cool and Heat Mode (Auto Changeover)

 – In this mode, the thermostat controls 

the cooling and heating systems, automatically changing over from one to the other as 

needed.

Program Mode

 – In this mode, the program function is on (PROG displays), and the 

thermostat will automatically be controlled by the set program schedule. Program mode can 

function with heat mode, cool mode or heat & cool mode. The program schedule can  be 

overridden by changing the set temperature (  or   button).  After 2 hours, the program 

schedule will automatically be resumed. To manually return to the program schedule, press 

the 

PROG button twice.

Cool Mode

• In this mode, the thermostat controls the cooling system

  

Note: There is a four minute delay for your compressor to restart after it has turned off.

Heat Mode

• In this mode, the thermostat controls the heating system

  

Note:  For heat pumps, there is a four minute delay for your compressor to restart after 

it has turned off.

OFF Mode

• In this mode, the thermostat will not turn on the heat pump.

Continuous Fan Mode

• The indoor fan can be turned on manually in every operating mode by sliding the auto/on switch to ON.

 

CAUTION

Do not energize the air conditioning system when the outdoor temperature is below 50 degrees.  

It can result in equipment damage or personal injury.

All manuals and user guides at all-guides.com

all-guides.com

Summary of Contents for 668811101

Page 1: ...Control Field Calibration Auto Changeover Button Lockout Function SimpleSet Programming Remote Temperature Sensor Capability Title 24 Compliant No Batteries Required Relay Outputs minimum voltage dro...

Page 2: ...nstallation Optional 3 Wiring Diagram 4 Configuration Mode 5 Starting the Thermostat 7 Testing the Thermostat 8 Mode of Operation 9 Operating Modes 10 Setting the Time and Day of the Week 11 Programmi...

Page 3: ...or switching the appropriate circuit breaker to the OFF position before removing the existing thermostat WARNING Always turn off power at the main power supply before installing cleaning or removing...

Page 4: ...ng the appropriate circuit breaker to the OFF position before removing the existing thermostat WARNING ELECTRICAL SHOCK HAZARD Turn off power at the main service panel by removing the fuse or switchin...

Page 5: ...y snapping it in place 6 Turn on power to the system at the main service panel 7 Test thermostat operation as described in Testing the Thermostat Remote Sensor Installation Optional 1 Remove cover fro...

Page 6: ...with heat pump air conditioning gas oil or electric heat systems 1 To enter the configuration mode simultaneously hold down the and buttons while the McQuay 668811101 thermostat is in OFF mode 2 Pres...

Page 7: ...e PROG button to advance to the next screen 3 Deadband 1 F 9 F 1 C 5 C Set the minimum number of degrees between your heating system activation and your cooling system activation Press the or button t...

Page 8: ...T Select the number of degrees set temperature can be changed during keypad lockout or select to lockout during NITE period only COOL HEAT lockout allows adjustment of the set temperatures to the maxi...

Page 9: ...the or button to select To exit configuration mode press the PROG button for 6 seconds Note First button press activates backlight only 1 Move the Fan Auto On switch to the Auto position 2 Press the M...

Page 10: ...For heat pumps there is a four minute delay to protect your compressor Fan Test 1 Slide fan switch to ON position Indoor fan turns ON 2 Slide fan switch to Auto position Indoor fan turns OFF Mode of O...

Page 11: ...ostat will stop outputting and the green light will turn off when the call for cooling is satisfied The thermostat will not let the compressor come on for 4 minutes after it turns off This protects yo...

Page 12: ...ostat will automatically be controlled by the set program schedule Program mode can function with heat mode cool mode or heat cool mode The program schedule can be overridden by changing the set tempe...

Page 13: ...are customizable for each day of the week Each period will have a start time heat temperature and cool temperature The McQuay 668811101 thermostat monitors the day and time while maintaining the speci...

Page 14: ...68811101 thermostat monitors the day and time while maintaining the specific conditions you have chosen for each period in your program 1 Press the MODE button until you are in the OFF mode 2 Press th...

Page 15: ...of the week individually or use the Simpleset feature see Page 14 to program every day the same as Monday When programming is complete press and hold the PROG button in for 5 seconds to return to the...

Page 16: ...the settings into memory Once the schedule is locked in you can go through each day and make any changes you require This feature speeds up the programming of the standard weekday weekend schedule 3 P...

Page 17: ...COOL 78 F COOL 82 F MONDAY thru SUNDAY Personal Program Schedule Factory Preprogramming The McQuay 668811101 thermostat comes preprogrammed with the following schedule Use the following personal progr...

Page 18: ...AT COOL COOL COOL COOL SUNDAY 7 Troubleshooting Symptom Remedy No display Check for 24 VAC at thermostat display is blank when 24 VAC is not present System fan does not come on properly Verify wiring...

Page 19: ...time AM PM check if in 2 hour program override Fan runs continuously Check Fan On Auto switch fan runs continuously in On position Status indicator light not on during call Turn status indicator funct...

Page 20: ...to Form 933 43285Y To find your local McQuay Representative go to www mcquay com This document contains the most current product information as of this printing For the most up to date product inform...

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