Carrier Access Thermidistat Control Troubleshooting, Vacation Dehumidification

	Thermidistat Control Troubleshooting
SYMPTOM	WHAT TO CHECK
No display	Open Thermidistat Control. Check for 24vac between R and C at screw terminals on mounting base. Reassemble, making
	sure pins on board engage sockets in mounting base. If display does not appear, replace Thermidistat Control.
"--" in place of room temperature	Thermidistat Control cannot properly read room temperature. Replace Thermidistat Control.
"E3" or "--" in place of outdoor temperature	Thermidistat Control cannot properly read outdoor temperature. Check outdoor sensor and its wiring.
"E4" or "E5"	Internal failure. Replace Thermidistat Control.
"E6"	System is stuck in defrost. Check wiring and heat pump defrost control board.
"Clean Filter" icon displayed	Filter timer has expired. Clean or replace filter and then press VACATION and HOLD/END buttons together to reset.
Cooling or heating will not come on	See Installer Setup to force heating or cooling. Check for 24vac at equipment terminals. If not present, check wiring.
Humidify or dehumidify will not come on	See Installer Setup to force HUM or DEHUM. Check for 24vac at equipment terminals. If not present, check wiring.

Vacation Dehumidification

Normal Dehumidify, Cool to Dehumidify, and Dehumidify OFF, are all available in vacation mode, and selection of 1 of these can be different from that of occupied. Vacation dehumidification selection and set points are remembered the next time vacation is used.

Cool to dehumidify operates slightly differently, allowing the home to be cooled to as low as 70°F when trying to achieve dehumidify set point. The balance between dehumidify and temperature set point adjustments is 1 percent set point increase per degree of overcooling for temperatures below 76°F. For example, at 74°F dehumidify set point is raised 2 percent, and at 72°F dehumidify set point is raised 4 percent. At temperatures above 76°F, dehumidify set point is not changed.

OPERATIONAL INFORMATION

FIVE-MINUTE COMPRESSOR TIMEGUARD

This timer prevents compressor from starting unless it has been off for at least 5 minutes. It can be defeated for 1 cycle by simultaneously pressing FAN button and INCREASE TEMPERA- TURE 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 hr. This timer is defeated for 1 cycle when desired temperature is manually changed. It can also be defeated for 1 cycle by simultaneously pressing FAN button and INCREASE TEMPERA- TURE button.

FIFTEEN-MINUTE STAGING TIMER

In multistage heating or cooling, this timer prevents any higher stage from turning on until preceding stage has been on for 15 minutes. This timer is defeated if temperature error is greater than 5°F (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. If the set point is changed, this timer is automatically canceled, allowing the equipment to turn off imme- diately when the demand is removed.

HEAT/COOL SET POINTS (DESIRED TEMPERATURE)

A minimum difference of 2° is enforced between heating and cooling desired temperatures. This is done by allowing 1 setting to "push" the other, to maintain this difference. This difference is adjustable via Configuration Option 14.

EQUIPMENT ON INDICATORS

When cooling equipment is on, a COOL icon preceded by a small triangle is displayed below cool set point. While cooling equip- ment turn on is delayed by a staging or cycle timer, triangle will flash. The same is true for HEAT icon and its preceding triangle

located under heat set point. These 2 arrows are also used to indicate state of humidify and dehumidify outputs. See next section.

HUMIDIFY AND DEHUMIDIFY INDICATORS

The humidity screen (selected by pressing the HUMIDITY button) uses the same triangles referenced in the above paragraph to indicate the state of the HUM and DHUM outputs. When humidification or dehumidification is active, the triangle under its set point is turned on.

AUTO CHANGEOVER

When 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 set point is changed, 20-minute requirement is deleted.

EMERGENCY HEAT MODE

When Thermidistat Control is configured as a heat pump and emergency heat 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 display are turned on for a few seconds. Following this, temperature display indicates model/configuration via 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 3-stage auxiliary heat, dFÐdual fuel, d2Ðdual fuel with 2-speed.

ERROR CODES

"--" Ð If Thermidistat Control cannot properly read room tem- perature, display will indicate -- and all outputs (except fan if on) will turn off.

E1, E2 Ð There is no E1 or E2 error message.

E3 Ð If Thermidistat Control cannot properly read outdoor temperature, and it is needed for proper operation, display will indicate E3.

E4 Ð If Thermidistat Control's internal memory fails, E4 will be displayed. Replace Thermidistat Control.

E5 Ð If Thermidistat Control cannot properly read humidity, E5 will be displayed. Replace Thermidistat Control.

E6 Ð If defrost cycle continues for longer than 15 minutes. E6 will be displayed. Check heat pump wiring or for failed heat pump defrost control.

SMART RECOVERY

With Smart Recovery selected, transition out of setback begins a fixed time period before selected recovery time and gradually adjusts room temperature so desired temperature will be achieved at selected recovery time. The fixed time period is 1.5 hr. It operates in both heating and cooling. This only applies to programmable operation.

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