Carrier 50TJ016-028 Installation, Start-up And Service Instructions Manual

Also see for 50TJ016-028: Installation, Start-Up and Service Instructions Installation, Start-Up and Service Instructions

Contents

31ELECTRONIC PROTECTION MODULE FAILUREDETECTION — If the compressor does not operate correctlyduring the functional test, this indicates a disturbance in opera-tion. Perform the following procedure:1. Switch off unit power at the unit mounted disconnectand lock out handle.2. Check the connection of the thermistor leads in the elec-tronic protection module terminal box for a loose connec-tion or possible breakage.3. The resistance of the thermistor chain is measured in acold condition (after the motor has sufficiently cooleddown). Measure resistance of the thermistor at the ther-mistor leads. Disconnect leads from terminals S1 and S2and measure between the leads. The resistance must be1250 ohms or lower. If the thermistor has a higherresistance, it is defective and the compressor must bereplaced.4. If no defect is found with the thermistors, and there is noloose contact or conductor breakage, the electronic pro-tection module should be checked. Before checking themodule, remove the connection at terminal M2, then re-turn control voltage to the module.a. Check for 24-V between the terminals T1 and T2.If no voltage is found, check unit wiring.b. With the R lead connected to either Y1 or Y2 asappropriate, check for 24-V between M1 and chas-sis ground. If voltage is not found, check unitwiring.c. With the thermistor leads removed from terminalsS1 and S2, and 24-V power applied to terminalsT1, T2, and M1, there should not be any voltagebetween terminals T2 and M2. If voltage ispresent, then the module is defective.d. With a jumper across module terminals S1 and S2,and with the R lead connected to either Y1 or Y2as appropriate, there should be 24 v between termi-nals M2 and T2. If not, the module is defective.EVAPORATOR-FAN MOTOR PROTECTION — A man-ual reset, calibrated trip, magnetic circuit breaker protectsagainst overcurrent. Do not bypass connections or increase thesize of the breaker to correct trouble. Determine the cause andcorrect it before resetting the breaker.CONDENSER-FAN MOTOR PROTECTION — Eachcondenser-fan motor is internally protected againstovertemperature.HIGH- AND LOW-PRESSURE SWITCHES — If eitherswitch trips, or if the compressor overtemperature switch acti-vates, that refrigerant circuit will be automatically locked outby the CLO. To reset, manually move the thermostat setting.FREEZE PROTECTION THERMOSTAT (FPT) — An FPTis located on the top and bottom of the evaporator coil. Itdetects frost build-up and turns off the compressor, allowingthe coil to clear. Once the frost has melted, the compressor canbe reenergized.Relief Devices — All units have relief devices to protectagainst damage from excessive pressures (i.e., fire). Thesedevices protect the high and low side.Control Circuit, 24-V — This control circuit is pro-tected against overcurrent by a 3.2-amp circuit breaker.Breaker can be reset. If it trips, determine cause of troublebefore resetting.EconoMi$er LEDs — The EconoMi$er control modulehas an LED for diagnostic purposes. The flash code identifica-tion is shown in Table 20.Optional Hinged Access Doors — When the optionalservice package is ordered or the if the hinged access doorsoption is ordered, the unit will be provided with external andinternal hinged access doors to facilitate service.Four external hinged access doors are provided. All externaldoors are provided with 2 large 1/4 turn latches with foldingbail-type handles. (Compressor access doors have one latch.) Asingle door is provided for filter and drive access. One door isprovided for control box access. The control box access door isinterlocked with the non-fused disconnect which must be in theOFF position to open the door. Two doors are provided for ac-cess to the compressor compartment.Two internal access doors are provided inside the filter/drive access door. The filter access door (on the left) is securedby 2 small 1/4 turn latches with folding bail-type handles. Thisdoor must be opened prior to opening the drive access door.The drive access door is shipped with 2 sheet metal screwsholding the door closed. Upon initial opening of the door, thesescrews may be removed and discarded. The door is then heldshut by the filter access door, which closes over it.Replacement Parts — A complete list of replacementparts may be obtained from any Carrier distributor uponrequest.Use maximum measuring voltage of 3V. Damage to ther-mistor could occur at higher voltages.The voltage should be switched off between voltage tests,in order to avoid short circuiting or accidental touching ofcontacts.