Carrier 58MVP Installation, Start-up, And Operating Instructions Manual

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Carrier 58MVP Installation, Start-up, And Operating Instructions Manual Manual pdf 38 page image

c. Check all return and supply ducts for excessive restrictionscausing static pressure greater than 0.5-in. wc.d. Ensure bypass humidifier switch (BPH) setup switch SW-3on control center is in ON position when a bypasshumidifier is used. (See Fig. 25 for switch location.)e. Check Troubleshooting Guide for Gas-Fired CondensingFurnaces.SET THERMOSTAT HEAT ANTICIPATORThe thermostat heat anticipator must be set to match the amp drawof the components in the R-W/W1 circuit. Accurate amp drawmeasurements can be obtained at the thermostat subbase terminalsR and W.Fig. 48 illustrates an easy method of obtaining thermostat ampdraw measurements. The amp reading should be taken after theblower motor has started and furnace is operating in low heat.1. To operate furnace in low heat, turn setup switch SW-2 to ONposition (See Fig. 25) and connect ammeter leads acrossthermostat subbase R-W.2. See the thermostat manufacturer’s instructions for adjustingthe heat anticipator and for varying the heating cycle length.NOTE: When using an electronic thermostat, set the cycle rate for3 cycles per hr.3. Return setup switch SW-2 to OFF position and replacethermostat on subbase.CHECK SAFETY CONTROLSStep 1—Check Primary Limit ControlThis control shuts off the combustion control system and energizesthe air-circulating blower motor if the furnace overheats.1. The recommended method of checking this limit control is togradually block off the return air after the furnace has beenoperating for a period of at least 5 minutes.2. As soon as the limit control has shut off the burners, a 33 faultwill appear on the control center.3. The return-air opening should be unblocked to permit normalair circulation.By using this method to check the limit control, it can beestablished that the limit is functioning properly and the furnacewill operate safely if there is a restricted return-air supply or motorfailure. If the limit control does not function during this test, thecause must be determined and corrected.Step 2—Check Pressure SwitchThis control proves operation of the draft inducer. Check switchoperation as follows:1. Turn off 115-v power to furnace.2. Remove control access door and disconnect inducer motor12-pin wire harness at inducer motor.3. Turn on 115-v power to furnace.4. Set thermostat to "call for heat." When the pressure switchesare functioning properly, fault code 42 will flash on thecontrol center approximately 10 sec after the thermostatswitch is closed. If either fault code 31 or 32 is flashed whenthe ICM inducer motor is disconnected, the furnace will shutitself down immediately. Determine the reason the pressureswitches did not function properly and correct the condition.5. Turn off 115-v power to furnace.6. Reconnect inducer motor wire harness. Reinstall furnaceaccess door.7. Turn on 115-v power to furnace.8. Reset thermostat to desired temperature.CHECKLIST1. Put away tools and instruments. Clean up debris.2. Verify manual reset switch has continuity.3. Verify that blower and control access doors are properlyinstalled.4. Cycle test furnace with room thermostat.5. Check operation of accessories per manufacturer’s instruc-tions.6. Review User’s Manual with owner.7. Leave literature packet near furnace.Fig. 48—Amp Draw Check with AmmeterA80201R Y W G10 TURNSTHERMOSTAT SUBBASETERMINALS WITHTHERMOSTAT REMOVEDHOOK-AROUNDVOLT/AMMETEREXAMPLE: 5.0 AMPS ON AMMETER10 TURNS AROUND JAWS = 0.5 AMPS FOR THERMOSTAT SETTINGFROM UNIT 24-VOLTTERMINAL BLOCK38

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