Carrier 48FK Controls Operation And Troubleshooting

Carrier 48FK Controls Operation And Troubleshooting Manual pdf 31 page image

START UNITTo start unit:1. Close the unit-mounted ON/OFF switch (located in themain control box).2. Close the field-supplied and -installed timeclock (or con-trol) switch (contacts located at Terminals 1 and 2 (TB3for 034-048, TB4 for 054-104).IMPORTANT: The field-supplied and installed switch(or timeclock) MUST BE CLOSED to put unit inOccupied mode. Unit WILL NOT START until thisis accomplished.3. Initialization mode begins (see Operating Information sec-tion on page 34 for complete description of sequencesand display codes).4. Run Quick Test. If the display button is pressed duringthe initialization mode period, the unit will run its self-88diagnostic routine. When this is in effect, an will ap-pear in the display screen. Refer to Quick Test Programsection below, for instructions on completing the QuickTest program.Quick Test Program — Turn on power to unit.IMPORTANT: The field-supplied switch (or time-clock) must be closed to put unit into the occupied mode.The quick test program utilizes the 2-digit LED display(see Fig. 6) on the set point board to show status of all inputand output signals to microprocessor. Display action and quicktest procedures are described below.The quick test program is a 33-step program that providesa means of checking all input and output signals of controlsprior to unit start-up. This check ensures that all control op-tions, thermistors, and control switches are in proper work-ing order.When unit control circuit is switched to Occupied mode,20a will appear on the display. Immediately press display88button once. An will appear on the display and alarmlight on display board will be energized. This indicates thatcontrol system is ready to run quick test program.IMPORTANT: Do not allow unit control circuit to20remain energized with showing on display for morethan 2 minutes. If display button is not pressed withinthis time period, control will attempt to start unit.For each step of the 33-step program, display button mustbe pressed twice. On first press, step number is displayed;second press initiates required action and appropriate codeis displayed.NOTE: The step number is a numeral followed by a decimalpoint (a 2-digit number has a decimal point after each nu-meral). The action code number is one or 2 digits with nodecimal point(s).IMPORTANT: Once quick test is initiated, display but-ton must be pressed at least once every 10 minutes forcontrol to remain in quick test mode. If button is notpressed within this time, control will attempt to startthe unit.To recheck any step in quick test program, control mustbe recycled by turning unit control switch off for a few sec-onds, and then turning it back on again. Restart quick testprogram as described above and proceed through quick teststeps. Press display button twice for each step until step tobe rechecked is reached.The quick test program is divided into 3 sections as de-scribed below and shown in Tables 15-17.1. Quick Test Steps 1.-1.3. — Unit Configuration and SwitchCheckThe microprocessor in unit control system is programmedby 2 switch assemblies located on processor board(Fig. 1). The configuration header is factory set and can-not be changed in the field. The DIP switch assembly con-tains 8 microswitches that must be set in accordance withthe various options selected by the customer. All DIPswitches should be checked and set to proper position foroptions selected prior to the quick test. See Configurationof Header and DIP Switch Assembly section on page 5for factory switch settings. The DIP switch functions anddisplay codes are shown in Table 15.2. Quick Test Steps 1.4.-2.3. — Thermistor and Set PointPotentiometer CheckIn these steps, the microprocessor checks resistance val-ues of all sensors and set point potentiometers to ensurethat they are functional, connected properly, and set withinproper range for unit configuration.Nominal resistance values for all sensors range from 363,000to 219 ohms in accordance with Table 18. Normal dis-play code for good sensors and potentiometers is 1. A dis-play code of 0 indicates a faulty potentiometer, thermistoror wiring. A 0 display also indicates that option is notbeing used.Table 16 shows thermistor and set point potentiometerfunctions and quick test display codes.31