Carrier 48VT(N) installation instructions 48VT--A, Symptom

Table 11 – Troubleshooting Guide - Cooling or Heat Pump Heating Mode

SYMPTOM	CAUSE	REMEDY
	Power Failure	Call power company.
	Fuse blown or circuit breaker tripped	Replace fuse or reset circuit breaker.
Compressor and Outdoor fan will not	Defective thermostat, contactor, transformer, or control	Replace component.
	relay
start.
	Insufficient line voltage	Determine cause and correct.
	Incorrect or faulty wiring	Check wiring diagram and rewire correctly.
	Thermostat setting too high	Lower thermostat setting below room temperature.
	Faulty wiring or loose connections in compressor circuit	Check wiring and repair or replace.
	Compressor motor burned out, seized, or internal over-	Determine cause Replace compressor.
Compressor will not start but Outdoor	load open
fan runs.
	Defective run/start capacitor, overload, start relay	Determine cause and replace.
	One leg of 3---phase power dead	Replace fuse or reset circuit breaker. Determine
		cause.
Three ---phase scroll compressor makes	Scroll compressor is rotating in the wrong direction	Correct the direction of rotation by reversing the
excessive noise, and there may
		3---phase power leads to the unit.
be a low pressure differential.
	Refrigerant overcharge or undercharge	Recover refrigerant, evacuate system, and recharge
		to capacities shown on nameplate.
	Defective compressor	Replace and determine cause.
Compressor cycles (other than normally	Insufficient line voltage	Determine cause and correct.
	Blocked Outdoor	Determine cause and correct.
satisfying thermostat).
	Defective run/start capacitor, overload or start relay	Determine cause and replace.
	Defective thermostat	Replace thermostat.
	Faulty Outdoor ---fan motor or capacitor	Replace.
	Damaged reversing valve	Determine cause and correct
	Restriction in refrigerant system	Locate restriction and remove.
	Dirty air filter	Replace filter.
	Unit undersized for load	Decrease load or increase unit size.
	Thermostat set too low	Reset thermostat.
	Low refrigerant charge	Locate leak, repair, and recharge.
Compressor operates continuously.	Mechanical damage in compressor.	Replace compressor.
	Air in system	Recover refrigerant, evacuate system, and recharge.
		Check defrost time settings, Reset as necessary
	Frosted coil with incorrect defrost operation	Check defrost temperature switch, Replace as nec-
		essary
	Outdoor coil dirty or restricted	Clean coil or remove restriction .
	Dirty air filter	Replace filter.
Excessive head pressure.	Dirty Indoor or Outdoor coil	Clean coil.
	Refrigerant overcharged	Recover excess refrigerant.
	Air in system	Recover refrigerant, evacuate system, and recharge.
	Indoor or Outdoor air restricted or air short---cycling	Determine cause and correct.
Head pressure too low.	Low refrigerant charge	Check for leaks, repair, and recharge.
	Compressor IPR leaking	Replace compressor.
	Restriction in liquid tube	Remove restriction.
	High heat load	Check for source and eliminate.
Excessive suction pressure.	Compressor IPR leaking	Replace compressor.
	Refrigerant overcharged	Recover excess refrigerant.
	Reversing valve hung up or leaking internally	Replace valve
	Dirty air filter	Replace Filter.
	Low refrigerant charge	Check for leaks, repair, and recharge.
	Metering device or low side restricted	Remove source of restriction.
	Insufficient Indoor airflow	Increase air quantity. Check filter — replace if neces-
Suction pressure too low.		sary.
	Temperature too low in conditioned area	Reset thermostat.
	Outdoor ambient below 55°F (12.8°C)	Install low---ambient kit.
	Field---installed filter ---drier restricted	Replace.
	(Heat) Outdoor coil frosted	Move timer on control board to 30 minutes between
		defrost cycles
Compressor runs but outdoor fan does	NC (normally closed) contacts on defrost board open	Check condition of relay on board Replace if neces-
not		sary

48VT-- A

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