Carrier 19XL specifications MAINT01, MAINT02, MAINT03, MAINT04, Occdefm, Wsmdefme

If the transducer value is not within the calibration range, the transducer will return to the original reading. If the LID pressure value is within the allowed range (noted above), check the voltage ratio of the transducer. To ob- tain the voltage ratio, divide the voltage (dc) input from the transducer by the supply voltage signal, measured at the PSIO terminals J7-J34 and J7-J35. For example, the condenser transducer voltage input is measured at PSIO terminals J7-1 and J7-2. The voltage ratio must be be- tween 0.80 vdc and 0.11 vdc for the software to allow calibration. Pressurize the transducer until the ratio is within range. Then attempt calibration again.

4.A high pressure point can also be calibrated between 240 and 260 psig (1655 and 1793 kPa) by attaching a regulated 250 psig (1724 kPa) pressure (usually from a nitrogen cylinder). The high pressure point can be cali- brated by accessing the transducer on the Status01 screen,

highlighting the transducer, pressing the SELECT soft- key, and then increasing or decreasing the value to the exact pressure on the refrigerant gage. Press ENTER

to ®nish. High altitude locations must compensate the pressure so that the temperature/pressure relationship is correct.

If the transducer reading returns to the previous value and the pressure is within the allowed range, check the volt- age ratio of the transducer. Refer to Step 3 above. The voltage ratio for this high pressure calibration must be between 0.585 and 0.634 vdc to allow calibration. Change the pressure at the transducer until the ratio is within the acceptable range. Then attempt calibrate to the new pres- sure input.

The PIC will not allow calibration if the transducer is too far out of calibration. A new transducer must be installed and re-calibrated.

TRANSDUCER REPLACEMENT Ð Since the transduc- ers are mounted on Schrader-type ®ttings, there is no need to remove refrigerant from the vessel. Disconnect the trans- ducer wiring by pulling up on the locking tab while pulling up on the weather-tight connecting plug from the end of the transducer. Do not pull on the transducer wires. Unscrew the transducer from the Schrader ®tting. When installing a new transducer, do not use pipe sealer, which can plug the sensor. Put the plug connector back on the sensor and snap into place. Check for refrigerant leaks.

Make sure to use a backup wrench on the Schrader ®t- ting whenever removing a transducer.

Control Algorithms Checkout Procedure Ð The Control Algorithm Status table is in the LID Service menu. The Control Algorithm Status table contains maintenance tables that may be viewed in order to see how the particular control algorithm is operating. The tables are:

MAINT01	Capacity	This table shows all values that
	Control	are used to calculate the chilled
		water/brine control point.
MAINT02	Override	Details of all chilled water control
	Status	override values are viewed here.
MAINT03	Surge/	The surge and hot gas bypass
	HGBP	control algorithm status is viewed
	Status	from this screen. All values deal-
		ing with this control are displayed.
MAINT04	LEAD/LAG	This screen indicates LEAD/LAG
(PSIO	Status	operation status.
Software
Version 09
and Higher)
OCCDEFM	Time	The Local and CCN occupied
	Schedules	schedules are displayed here in
	Status	a manner that the operator can
		quickly determine whether the
		schedule is in the OCCUPIED
		mode or not.
WSMDEFME	Water	The water system manager is a
	System	CCN module which can turn on
	Manager	the chiller and change the chilled
	Status	water control point. This screen
		indicates the status of this system.

These maintenance tables are very useful in determining how the control temperature is calculated, the position of the guide vane, reaction from load changes, control point over- rides, hot gas bypass reaction, surge prevention, etc.

Control Test Ð The Control Test feature can check all of the thermistor temperature sensors, including those on the Options modules, pressure transducers, pumps and their associated ¯ow switches, the guide vane actuator, and other control outputs, such as hot gas bypass. The tests can help to determine whether a switch is defective, or a pump relay is not operating, among other useful troubleshooting tests. During pumpdown operations, the pumps are energized to prevent freeze-up and the vessel pressures and temperatures are displayed. The lockout feature will prevent start-up of the compressor when no refrigerant is present in the chiller, or if the vessels are isolated. The lockout is then terminated by the operator by using the Terminate Lockout function after the pumpdown procedure is reversed and refrigerant is added.

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