Carrier 040-420 specifications Example 2 Reading Current Operating Modes, Keypad Display

Example 2 - Reading Current Operating Modes

KEYPAD	DISPLAY		COMMENTS
ENTRY	I RESPONSE	I

m H (Analog Inputs) - This subfunction displays analog inputs, if any. Enter m Fi , then use the q . The

p-lH

c4 l

c+ l

TUE 15:45

LOCAL ON

COOL 1

0 ALARMS

2MODES LOCAL ON M O D E 8

Keypad has not been used for at least 10 minutes Rotating summary display appears on screen

There are 2 modes currently in effect

Unit is on by chiller on/off switch

Temperature reset is in effect

transducer supply voltage, 4-20 mA reset signal can be dis- played. This is useful for problem diagnosis prior to using the test function.

m(I bin p u t s ) - This subfunction displays status

(ON/OFF) of input switch where applicable. Status of dual set point switch, and demand limit switches 1 and 2 can be displayed. This is useful for problem diagnosis prior to us- ing the test function.

~~ (Outputs) - This function displays ON/OFF sta-

l-ii 1;;;;1 (Stage) - This subfunction displays the capac-

ity stage number. See Tables 4A-4D for compressor load- ing sequence. To enter the STAGE subfunction, press

p--&q and use the q to display the stage number.

Additional m provides the following information:

Percent of total unit capacity being utilized. Percent of each circuit capacity being utilized.

Demand limit set point in effect (can be any value be- tween 0% and 100%).

Load limit set point in effect. This is a CCN function for controlling operation of multiple units between 0% and 100% of total capacity of all units combined.

Status of each compressor relay. When a compressor is on, the number of that compressor is displayed. If a com- pressor is off, a 0 is displayed. For example: In a given circuit, if compressors 1 and 3 are running, and 2 and 4 are not running, 0301 is displayed for that circuit.

Load/Unload factor for compressors. This factor is an in- dication of when a step of capacity is added or sub- tracted. Its value can range from slightly less than -1 .O to slightly more than + 1 .O. When load/unload factor reaches + 1.0, a compressor is added. When the load/ unload factor reaches -1 .O, a compressor is subtracted. If compressor unloaders are used, at -.6 a compressor is unloaded and at + .6, a compressor is loaded up.

mF[ (Set Point) - This subfunction displays leaving

water temperature and leaving chilled water set point. If unit is programmed for dual set point, the chilled water set point currently in effect (either occupied or unoccupied) is displayed. If reset is in effect, the unit operates to the mod- ified chilled water set point. This means the leaving water temperature may not equal the chilled water set point The modified chilled water set point can also be displayed in the Status function. To enter the set point subfunction, de-

press mb[ and use the q to display modified leaving

chilled water set point followed by leaving water set point and actual cooler leaving fluid temperature.

F[(Temperature)F[- The temperature subfunction dis-

plays the readings at temperature sensing thermistors.

To read a temperature, enter Fi Fi , then scroll to de-

sired temperature using the m key. See Table 9 for the order of readouts.

flH (Pressure) - This subfunction displays suction,

discharge and net oil pressure at lead compressor of each circuit of unit.

tus of alarm relay, all fan relays, and chilled water pump relay. It also displays ON/OFF status of compressor unload- ers (if used). The position of each EXV (in percent open) can be displayed.

TEST FUNCTION - The test function operates the diag- nostic program. To initiate test function, the LOCAL/ ENABLE-STOP-CCN switch must be in STOP position.

To reach a particular test, enter its subfunction number, then scroll to desired test by pressing the ( key. Press B to start a test. Press q or q or H to terminate or

exit a test. Pressing the q key after a test has started ad-

vances system to next test, whether current test is operating or has timed out, Once in the next step, you may start

test by pressing H or advance past it by pressing I)I .

While the unit is in test, you may leave test function and access another display or function by pressing appropriate keys. However, a component that is operating when an- other function is accessed remains operating. You must

re-enter test function and press the ) key to shut down

the component. Components with a timed operating limit time out normally even if another function is accessed.

Keypad entry riF[ allows the operator to make the

following checks by using m :

LID display check. Propezisplay is 8.8.8.8.8.8.8.8 . Operation of remote alarm.

Operation of condenser fans. Operation of chilled water pump.

Operation of EXVs. To drive EXV fully open, enter m m m (100% open). To drive EXV fully closed, en-

ter u (0% open).c

K e y p a d e n t r y. -mH Iaccesses the compressor and

compressor unloader operational tests.

During compressor operational tests, compressor starts and runs for 10 seconds. Compressor service valves must be open. Energize crankcase heaters 24 hours prior to performing compressor tests.

Since test function checks only certain outputs, it is good practice to also check all inputs and outputs accessible

through the status function. These are located at F\ F[ , m H, and mm (see Table 9). If keypad is not used

for 10 minutes, unit automatically leaves test function and resumes rotating display. See Example 3.

38