Carrier 69NT20-531-300 manual Valve Override Controls

under load conditions. The important advantages of a analyzer are its ability to locate capacitors that have failed to hold their microfarad ratings, or those that are breaking down internally during operation. It is also useful in identifying capacitors when their microfarad rating marks have become unreadable.

6.19 VALVE OVERRIDE CONTROLS

CAUTION

DO NOT disassemble piston from NEW suc- tion modulating valve powerhead assembly. Doing so may result in damage to piston.

Controller function code Cd41 is a configurable code that allows timed operation of the automatic valves for troubleshooting. Three test sequences are provided. The first, capacity mode (CAP), allows alignment of the unloader and economizer solenoid valves in the standard, unloaded and economized operating configurations. The second, SMV % Setting (SM) allows opening of the suction modulating valve to various percentages and the third, Oil Valve Setting (OIL) and Liquid Valve Setting (LIV) allows opening or closing of the oil return solenoid valve and the liquid injection solenoid valve. A fourth selection is also provided to enter a time period of up to three minutes, during which the override(s) are active. If the timer is active, valve override selections will take place immediately. If the timer is not active, changes will not take place for a few seconds after the timer is started. When the timer times out, override function is automatically terminated and the valves return to normal machinery control. To operate the override, do the following:

a.Press the CODE SELECT key then press an ARROW key until Cd41 is displayed in the left window. The right window will display a controller communica- tions code.

b.Press the ENTER key. The left display will show a test name alternating with the test setting or time re- maining. Use an ARROW key to scroll to the desired test. Press the ENTER key and SELCt will appear in the left display.

c.Use an ARROW key to scroll to the desired setting, and then press the ENTER key. Selections available for each of the tests are provided in the following table.

d.If the timer is not operating, follow the above proce- dure to display the timer. Use an ARROW key to scroll to the desired time interval and press ENTER to start the timer.

e.The above described sequence may be repeated dur- ing the timer cycle to change to another override.

Right Display	Available Selections
CAP	AUtO
(Capacity Mode)	(Normal Control)
	UnLd
	(Unloader = Open
	Economizer = Closed)
	Std
	(Unloader = closed
	Economizer = closed)
	ECOn
	(Unloader = closed
	Economizer = open)
SM	AUtO
(SMV % Setting)	(Normal Control)
	0
	3
	4
	6
	12
	25
	50
	100
OIL	AUto
(Oil Valve Setting)	(Normal Control)
	CLOSE
	OPEn
LIV	AUto
(Liquid Valve Setting, if	(Normal Control)
applicable)	CLOSE
	OPEn
tIM	0 00 (0 minutes/0 Seconds)
(Timer)	In 30 second increments to
	3 00 (3 minutes/ 0 seconds)

6.20 SUCTION MODULATION VALVE

On start up of the unit, the valve will reset to a known open position. This is accomplished by assuming the valve was fully open, driving it fully closed, resetting the percentage open to zero, then opening to a known 10% staging position.

FROM COIL 2-1/8 inch Nut

TO COMPRESSOR

FROM UNLOADER

Figure 6-17 Suction Modulation Valve (SMV)

6-13 T-309