Carrier 39L Example 1 Ð Reading Alarm Codes, Example 2 Ð Reading Current Operating Modes

STATUS FUNCTION Ð The status function shows the cur- rent status of alarm (diagnostic) codes, operating modes, set points, all measured system temperatures, output values, and input values. These subfunctions are de®ned on pages 78-80. Refer to Table 11 for additional information.

(Alarms) Ð Alarms are messages that one or more

faults have been detected. Each fault is assigned a code num- ber which is reported with the alarm. (See Table 14 for code de®nitions.) The codes indicate failures that cause the unit to shut down, terminate an option (such as reset), or result in the use of a default value as the set point.

Up to 32 alarm codes can be stored at once. To view

them in numerical sequence, press to enter the

alarm display and then press to move to the individual

alarm displays. Press after a code has been displayed

and the meaning of the code will scroll across the screen. See Example 1.

If an input or output point which has generated an alarm resets (returns to a range within its limits), the alarm code is deleted from the list.

A historical sequence of the last 9 alarms can be found

using the key. See Display Functions, History Func-

tion section for more details.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

(Modes) Ð The operating mode codes are dis-

played to indicate the current operating status of the unit. (See Table 14)

To enter the MODES subfunction, press and use

the key to determine if more than one mode applies.

See Example 2 to read current mode with expansion.

Example 1 Ð Reading Alarm Codes

KEYBOARD	DISPLAY	COMMENTS
ENTRY	RESPONSE
	TUE 12:45	Keyboard has not been used for
	MODE 23	at least 10 minutes; alternating
		summary display appears on
	3 ALARMS
		screen
	3 ALARMS	3 alarms detected
	ALARM 71	First alarm code
	SPACE	Explanation of alarm code
	TEMPERATURE
	LOW LIMIT
	ALARM 76	Second alarm code
	RETURN AIR	Explanation of alarm code
	TEMPERATURE
	HIGH LIMIT
	ALARM 83	Third alarm code
	RELATIVE
	HUMIDITY	Explanation of alarm code
	LOW LIMIT

The modes are explained below:

Temperature Reset (21) Ð Indicates that the unit is using temperature reset to adjust the supply-air set point. The set point is modi®ed based on space temperature (VAV units only). Unit must be con®gured for space temperature

reset ( ). (This mode is enabled by .)

Demand Limit (22) Ð On CV (constant volume) units, this mode indicates that the fan is being held off by the De- mand Limit option. On VAV units, it indicates that the max- imum IGV position is being limited by the Demand Limit option. Units must be con®gured for demand limiting

( ). This mode is enabled by , and is only

available on units connected to the Carrier Comfort Network (CCN).

Unoccupied Heating (23) Ð Indicates that the space tem- perature is below the Unoccupied Heating set point and the unit is on. When the space temperature rises above the set point the unit is turned off.

Unoccupied Cooling (24) Ð Indicates that the space tem- perature is above the Unoccupied Cooling set point and the unit is on. When the space temperature falls below the set point the unit is turned off.

Optimal Start (26) Ð Indicates that the unit is operating in the Optimal Start mode and is trying to achieve the Occupied set point. On VAV units this is referred to as morn- ing warm-up. Unit must be con®gured for optimal start

( ). This mode is enabled by .)

Unoccupied Mode (27) Ð Indicates that the unit is in the Unoccupied mode as determined by its time schedule. In this mode the unit is turned off.

Optimal Stop (29) Ð Indicates that the unit is being con- trolled to its expanded Occupied set points. The space tem- perature is allowed to drift to its expanded Occupied set points during the last portion of the Occupied period.

Unit must be con®gured for Optimal Start ( ). Optimal Stop mode is only applicable to CV units.

Occupied Heating (30) Ð Indicates that the unit is in the Heating mode to satisfy its Occupied Heating set point.

Units must be con®gured for Occupied Heating

( ).

Occupied Heating is available on VAV units only.

Example 2 Ð Reading Current Operating Modes

KEYBOARD	DISPLAY	COMMENTS
ENTRY	RESPONSE
	TUE 12:45	Keyboard has not been
	MODE 31	used for at least 10 min-
		utes; alternating summary
		display appears on screen.
	MODE	Modes subfunction of
		status function
	MODE 31	Mode 31 is in effect
	OCCUPIED COOLING	Explanation of code 31
	MODE 22	Mode 22 is in effect
	DEMAND LIMIT	Explanation of code 22

NOTE: The ®rst mode is the primary operating mode. The second mode is the secondary operating mode, if applicable.

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