Carrier 50FK, JK034-074, 48FK specifications Operating Information, Sensor Resistance Values

Table 18 Ð Sensor Resistance Values

TEMP	RESISTANCE	TEMP	RESISTANCE	TEMP	RESISTANCE
(F)	(Ohms)	(F)	(Ohms)	(F)	(Ohms)
−60	362,640	45	11,396	150	1,020
−55	297,140	50	9,950	155	929
−50	245,245	55	8,709	160	844
−45	202,841	60	7,642	165	768
−40	168,250	65	6,749	170	699
−35	139,960	70	5,944	175	640
−30	116,820	75	5,249	180	585
−25	98,420	80	4,644	185	535
−20	82,665	85	4,134	190	490
−15	69,685	90	3,671	195	449
−10	58,915	95	3,265	200	414
−5	50,284	100	2,913	205	380
0	42,765	105	2,600	210	350
5	36,475	110	2,336	215	323
10	31,216	115	2,092	220	299
15	26,786	120	1,879	225	276
20	23,164	125	1,689	230	255
25	19,978	130	1,527	235	236
30	17,276	135	1,377	240	219
35	14,980	140	1,244
40	13,085	145	1,126

3.Quick Test Steps 2.4.-3.3. Ð Output Relay Check

These quick test steps allow microprocessor to check output signals from relay boards in unit control system. In ad- dition, operation of all the condenser fans, compres- sors, and economizer (if equipped) are checked at each step.

Normal display for Steps 2.4. through 2.8. is 1. In Steps

2.9.through 3.2., each compressor and unloader is started and allowed to run for approximately 10 seconds. At start- up, a 0 will appear on the display followed by a 1 (Steps

2.9.and 3.2.) in a few seconds. Steps 3.0. and 3.1. will always be 0 since there are unloaders, and Step 3.3. will always be zero since it is not used.

At end of the 10-second time period, a 0 will return to the display board indicating that test step has been success- fully completed (Steps 2.9. and 3.2.). The 1 indicates that was tested.

Fan and compressor operating sequence for quick test Steps 2.4. through 3.3. are shown in Table 17.

If the quick test steps do not operate as described above, a defect exists in one or more of the following: relay being tested, electronic control, or unit wiring. Determine problem and correct.

OPERATING INFORMATION

Digital Display Ð The VAV control system uses a 2-digit LED display located on the display board to display opera- tional information and diagnostic codes.

CODES 0 THROUGH 8, CAPACITY STEPS Ð These codes indicate the number of cooling stages active at the time the display button is pressed. The highest code indicated on the display will be 6 for the 034,038 and 048-088 units, 4 for the 044 units, and 8 for the 104 units.

Capacity steps are directly related to pin terminal connec- tor J6 output. At step zero, the unit has no mechanical cool- ing on, and the economizer may or may not be operating (depending on the outdoor air conditions). Once a cooling load is detected (T1 thermistor reads above the supply-air set point), the economizer will begin modulating to meet the

load if the outdoor enthalpy is good. As long as the outdoor- air enthalpy is acceptable, no mechanical cooling will take place until the economizer dampers are fully open. The rest of the steps and the operational sequence vary due to the number of compressors and unloaders. Refer to Operating Sequence section on page 35 for the unit stages of operation.

CODES 20 THROUGH 30 AND 88, OPERATIONAL STA- TUS Ð These codes indicate special operational modes, such as initialization, morning warm-up, temperature reset, de- mand limit, or an internal failure of the board. Codes 23-25 and 27-29 are not used on these units.

Initialization Ð When the control is turned on, the display shows a 20 for approximately 2 minutes to indicate that the

control is in the initialization mode. During this time, the economizer dampers open and close to determine the resis- tance range of the economizer position potentiometer (P2) for full economizer operation. The processor loads the nec- essary constants for proper unit operation and checks the ther- mistors and other potentiometers for their values and valid- ity. After the initialization period, the display screen goes blank until the display button is pressed. If the display but- ton is pressed during the 2-minute initialization period, the control goes into the Quick Test mode.

Temperature Reset Ð If the unit is equipped with the ac- cessory temperature reset package, and DIP switch 2 is in the ON position, the unit will reset the supply-air tempera- ture to a calculated value when necessary. When this con- dition is in effect, a 21 will appear in the display.

Demand Limit Ð If the unit is equipped with the accessory demand limit control module or the ®eld-supplied, single- step demand limit potentiometer, and DIP switch 5 is in the ON position, the unit will limit the capacity stages to a pre-

determined value. When this condition is in effect, a 22 will appear in the display.

Morning Warm-Up ÐIf the morning warm-up heat routine is enabled using DIP switch 4, and conditions of the occu- pied space warrant, the unit will begin the morning warm-up

routine. When this condition is in effect, a 26 will appear in the display.

Internal Failure Ð If the unit detects an internal fault (such as a time measurement failure), or detects an incorrect volt- age on an input channel, a 30 will be displayed, and the unit will shut down.

Quick Test Ð If the display button is pressed during the initialization period of the processor, the unit will run its self- diagnostic routine. When this is in effect, an 88 will appear in the display screen.

CODES 51 THROUGH 87, DIAGNOSTIC INFORMA- TION Ð These codes indicate diagnostic information when there is a unit problem such as a faulty thermistor, potenti- ometer, or compressor fault. Refer to Diagnostic Codes sec- tion on page 45 for more details. Codes 53, 54, 57, 58, 61, 62, 65-69, 73, 74, and 77-80 are not used on these units.

Under normal operation, only the stage number is dis- played when the display button is pressed. If a status or over- load code is displayed, the display will rotate every 2 sec- onds and will display up to 3 codes. Overload information takes priority over all other codes. The codes are stored in the microprocessor as long as the board remains energized.

34