Carrier 50BV020-064 Unit Troubleshooting, Problem, Possible Cause, Correction Procedure

Table 28 — Unit Troubleshooting

PROBLEM	POSSIBLE CAUSE	CORRECTION PROCEDURE
Unit Will Not Start.	Loss of unit power	Check power source.
		Check fuses, circuit breakers, disconnect switch.
		Check electrical contacts.
	Unit voltage not correct	Check and correct.
	Open fuse	Check for short circuit in unit.
	Open protection device	Check relays (phase monitor option), contacts, pressure switches.
	Unit or motor contactor out of order	Test and replace if necessary.
Fan Does Not Operate.	Contactor or relay overload or out of order	Test and replace if necessary.
	VFD not running	Perform VFD diagnostic test.
	Motor defective	Test and replace if necessary.
	Broken belt	Replace belt.
	Loose electrical contact	Tighten contact.
Compressor is Noisy, But	Under voltage	Check and correct.
Will Not Start.
	Defect in compressor motor	Replace compressor.
	Missing phase	Check and correct.
	Compressor seized	Check and replace if necessary.
Compressor Starts,	Compressor or contact defect	Test and replace if necessary.
But Does Not Continue
	Unit is under charged	Check and correct any leaks. Add refrigerant.
to Run.
	Unit is too big	Check load calculation.
	Compressor is overloaded	Check protection device and replace.
		Check for missing phase.
		Check TXV.
		Check temperature in suction discharge line.
Unit is Noisy.	Compressor noise	Check TXV and replace if necessary.
		Compressor rotation incorrect; check and correct.
		Check internal noise.
	Tube vibration or condenser water problem	Check and correct.
	Unit panel or part vibrating	Check and tighten appropriate part.
Unit Runs Continuously,	Unit is too small	Check load calculation.
But Has Low Capacity.
	Low refrigerant or noncondensing gas present	Check for leaks and add refrigerant or gas as necessary.
	Compressor defect	Check pressure and amps. Replace if necessary.
	Insufficient flow of refrigerant in evaporator	Check filter drier and replace if necessary.
		Check TXV and adjust or replace if necessary.
		Check position of TXV bulb and equalizer.
	Oil in evaporator	Drain evaporator.
	Low airflow	Check filters, and clean or replace as necessary.
		Check coils, and clean as necessary.
		Check for restrictions in ductwork.
		Check fan rotation and adjust.
		Check fan motor.
		Check belts for wear.
High Discharge Pressure.	Low waterflow in condenser	Purge air.
	Dirty condenser tubes.	Clean condenser.
	High temperature in condenser water	Check water tower fans and pumps.
	Overcharged	Check and reclaim excess charge.
		Adjust subcooling.
	Noncondensing gas present	Verify and correct.
LEGEND

TXV — Thermostatic Expansion Valve

VFD — Variable Frequency Drive

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