Carrier instruction manual → Thermostat Troubleshooting, → Operational Information

→OPERATIONAL INFORMATION

Five-minute Compressor Timeguard

This timer prevents the compressor from starting unless it has been off for at least 5 minutes. It can be defeated for 1 cycle by simultaneously pressing the FAN mode button and the INCREASE TEMPERATURE button.

Fifteen-minute Cycle Timer

This timer prevents the start of a heating or cooling cycle until at least 15 minutes after the last start of the same cycle. Its function is to assure that equipment is not cycled more than 4 times per hour. This timer is defeated for 1 cycle when the desired temperature is manually changed. It can also be defeated for 1 cycle by simultaneously pressing the FAN mode button and the INCREASE TEMPERATURE button.

Fifteen-minute Staging Timer

In multistage heating or cooling, this timer prevents any higher stage from turning on until the preceding stage has been on for 15 minutes. This timer is defeated if the temperature error is greater than 5ÊF (usually due to a large change in desired temperature).

Three-minute Minimum On Time

In normal operation, when a stage turns on, it will not turn off for a minimum of 3 minutes.

Heat/Cool Set Points (Desired Temperatures)

A minimum difference of 2 degrees is enforced between heating and cooling set points. This is done by allowing one setting to "push" the other, to maintain this difference.

Auto Changeover

When the auto changeover mode is selected, a change from heat to cool (or vice versa) will not occur until an opposite mode demand has existed for 20 minutes. If the setpoint is changed, the 20 minute requirement is deleted.

Emergency Heat Mode

When thermostat is configured as a heat pump and emergency heat mode is selected, all Y signals are locked out and W becomes energized upon a call for heat.

Power On Check

When AC power is first applied, all segments of the display are turned on for a few seconds. Following this, the temperature display indicates the model/configuration via the following 2 digit code:

ACÐ1-speed air conditioner, HPÐ1-speed heat pump, A2Ð2-speed air conditioner, H2Ð2-speed heat pump, HSÐ1-speed heat pump with Intelligent Heat staging (3-stage auxiliary heat).

Error Codes

--Ð If the thermostat cannot properly read room temperature, the display will indicate "--" (2 dashes) and all outputs (except the fan if on) will turn off. This is to prevent operation of the equipment if the thermostat has failed.

E2 Ð If the AC line voltage drops below a minimum (brownout) level, all outputs are turned off and the display indicates E2. This condition will remain for 15 seconds after proper line voltage is restored. If the AC line voltage disappears completely, the display will immediately go blank.

E3 Ð If thermostat cannot properly read outdoor temperature, and/or it is needed for proper operation, (i.e. Option 8 is ON with no sensor attached), E3 will alternate with room temperature on the room temperature display and the outdoor temperature will read "--".

Outdoor Temperature

When an outdoor temperature sensor is attached, outdoor temperature can be read by pressing up and down buttons together. While it is displayed, the letters "od" also appear in the heat set point display.

Smart Recovery

With Smart Recovery selected, the transition out of a heating setback begins 90 minutes early, gradually adjusting room temperature so that the desired temperature will be achieved at the selected time.

→Thermostat Troubleshooting

SYMPTOM	WHAT TO CHECK
"--" on temperature display	Temperature sensor reading out of range. Check sensor for damage. If recycyling power
	does not clear display, thermostat should be replaced.
"E2" on temperature display	Brownout condition or too low of voltage to thermostat. Double check wiring and check for
	24 VAC between R and C. E2 will clear 15 seconds after proper voltage is restored.
"E3" on temperature display	Outdoor temperature reading out of range and needed for Option 8. Check outdoor tem-
	perature sensor and its wiring.
"Clean Filter" on temperature display	After the selected number of hours of blower operation "clean filter" will display on LCD.
	This is to remind the homeowner to "check" filter. Press "reset filter" button to clear dis-
	play and reset timer to 0.
	Select COOL mode. Decrease cooling setpoint to 10 degrees below room temperature.
Cooling will not come on	Simultaneously press FAN and INCREASE TEMPERATURE buttons to defeat timers.
	Check for 24 VAC at Y/Y2 terminal. If present, thermostat is OK and problem is with
	equipment or wiring. If not present, replace thermostat.
	Select HEAT mode. Increase heating setpoint to 10 degrees above room temperature.
Heating will not come on	Simultaneously press FAN and INCREASE TEMPERATURE buttons to defeat timers.
	Check for 24 VAC at Y/Y2 (with HP) or W/W1 (with AC) terminal. If present, thermostat is
	OK and problem is with equipment or wiring. If not present, replace thermostat.

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