Carrier T--298 service manual Upper Unit, Powerbox Assembly, Thermostat

3.11.2 Timeguard Timer

A3--minute timeguard is built into the thermostat immediately upon power up, and any time the compressor (output “Y”) turns off. The compressor will not turn on until the timeguard has expired. Pressing UP and FAN buttons simultaneously will override the timeguard for 1 cycle.

3.11.3 Cycle Timer

In normal cooling (and heating) operation the thermostat will not allow more than 4 equipment cycles per hour (or 1 cycle every 15 minutes). Both the “Y” (cooling) and “W” (heating) outputs have a 15--minute timer that starts counting down when the output is turned on, (e.g., if “Y” output is turned on for 9 minutes and then satisfies, it cannout turn back on for another 6

minutes regardless of demand). However, pressing UP and FAN buttons simultaneously or changing the set point will override the timer for 1 cycle.

3.11.4 Minimum On Timer

Once the equipment has turned on, it will remain on for a minimum of 2 minutes regardless of demand. However, the equipment can turn off in less than 2 minutes if a change in set point, or a changein mode occurs.

3.11.5 Error Messages

E4 will be displayed if the thermostat has an internal memory failure. If E4 appears, replace the thermostat.

----(two dashes) will be displayed if the thermostat cannot properly read the room temperature. If ----

appears, replace the thermostat.

UPPER UNIT

Factory Wiring

Field Wiring

	Motor			Comp.
1	2	3	4	2	1

1	2	3	4	J
					L
					N2
					N1
POWERBOX
ASSEMBLY
					1	W

115V AC High Voltage

Power Supply

THERMOSTAT

2	Y
3	GH
4	GL
5	C

Y

GH

GL

R

C

COOL (Compressor)

FAN (High)

FAN (Low)

12VDC LowVoltage

Power Supply

CEILING UNIT

Figure 3-40 Wall Thermostat Wiring Diagram -- Cool Only Model
3-17	T--298