Troubleshooting, Fault Code | Carrier 40QNC, 40QNQ specs

TROUBLESHOOTING

See Table 12 and Table 13 for troubleshooting information.

Fault Code

Once a failure occurs with the indoor unit in operation, the green LED on the indoor unit flashes at intervals of 0.5 seconds. The fault code is deduced from the number of times the green LED flashes, blocking unit operation. Between one flash cycle and the next one, a pause of 3 seconds elapses.

	Table 12 – Green LED (Indoor Unit Fault)

CODE	DESCRIPTION
3	Room Air Sensor Fault
4	Indoor Unit Coil Sensor Fault
14	Outdoor Unit Air Sensor Fault

Table 13 – Troubleshooting

PROBLEM	POSSIBLE CAUSE	SOLUTION
	Unit not energized	Check the main power connection.
Compressor and Fan of the Outdoor	Main switch is set to OFF	Check and put it to ON position.
Compressor and Fan of the Outdoor	Main switch fuses are blown	Replace fuses.
Unit Will Not Start	Compressor cycling protection is on	Wait for 3 minutes.
	Main power voltage is too low	Check and set to the correct voltage.
	Electrical connections are too loose or are wrong	Check and tighten or correct connections.
Compressor Will Not Start, But Out-	Electrical connections of compressor are loose or	Check and tighten or repair compressor.
door Fan is Operating	wrong	Check and tighten or repair compressor.
door Fan is Operating	wrong
	Compressor burnt out; seized or protection device	Check for the cause and replace compressor if neces-
	on	sary.
	Wrong refrigerant charge in unit (excessive or low)	Drain refrigerant, evacuate and recharge. CAUTION: Do
	or air or other non ---condensable gasses in the	not vent refrigerant to the atmosphere; use refrigerant
	circuit	recovery equipment.
Compressor Stops Due to Over---tem-	Main voltage is too high or too low	Check voltage setting and adjust if necessary.
Compressor Stops Due to Over---tem-	Condenser coil obstructed	Remove obstruction.
perature	Outdoor fan off	Check cause and resume operation or repair.
	Wrong indoor unit thermistors	Replace thermistors.
	Refrigerant circuit clogged	Check and remove obstructions.
	Reversing valve faulty on heat pump models	Replace reversing valve.
		Drain refrigerant, evacuate and recharge. CAUTION: Do
	Expansion device clogged or covered with ice	not vent refrigerant to the atmosphere; use refrigerant
		recovery equipment.
	Unit selected is too small for application require-	Contact a qualified service technician for a system evalu-
	ments	ation.
	Indoor temperature setting too low or too high	Check temperature setting.
Compressor Runs Continuously	Outdoor unit fan faulty	Replace outdoor fan.
Compressor Runs Continuously	Air or other non ---condensable gasses in the cir-	Drain refrigerant, evacuate and recharge. CAUTION: Do
		Drain refrigerant, evacuate and recharge. CAUTION: Do
		not vent refrigerant to the atmosphere; use refrigerant
	cuit	not vent refrigerant to the atmosphere; use refrigerant
	cuit	recovery equipment.
		recovery equipment.
	Obstructions at air intake or dirty indoor unit filters	Remove obstruction and/or clean filter.
Frequent Ice ---Build---Up on Outdoor	Outdoor fan is stopped	Check cause and repair.
Coil	Outdoor fan is stopped	Check cause and repair.
Coil
	Outdoor coil dirty or obstructed	Clean or remove obstructions.
	Condenser fan faulty	Replace condenser fan.
Discharge Pressure Too High	Indoor temperature setting too low or too high	Check temperature setting.
Discharge Pressure Too High	Air or other non ---condensable gasses in the cir-	Drain refrigerant, evacuate and recharge. CAUTION: Do
		Drain refrigerant, evacuate and recharge. CAUTION: Do
		not vent refrigerant to the atmosphere; use refrigerant
	cuit	not vent refrigerant to the atmosphere; use refrigerant
	cuit	recovery equipment.
		recovery equipment.
Discharge Pressure Too Low	Indoor temperature setting too high or too low	Check temperature setting.
Discharge Pressure Too Low	Outdoor coil dirty or obstructed	Clean or remove obstructions.
	Indoor unit air filter dirty	Clean filter.
Suction Pressure Too High	Indoor temperature setting too high or too low	Check temperature setting.
Suction Pressure Too High	Reversing valve faulty or internal leak	Replace reversing valve.
	Reversing valve faulty or internal leak	Replace reversing valve.
	Indoor temperature setting too high or too low	Check temperature setting.
	Evaporator coil covered with ice	Air circulation on the evaporator not sufficient; check and
Suction Pressure Too Low	Evaporator coil covered with ice	repair.
Suction Pressure Too Low		repair.
	Expansion device or suction line clogged	Check and repair.
	Outdoor fan does not stop during defrost periods	Check electrical parts.
	Electrical connection loose	Check connections.
Outdoor Fan Cycling Due to Over---	Fan motor burn out	Replace.
Outdoor Fan Cycling Due to Over---	Fan bearing seized	Check and repair.
Temperature Protection		Drain refrigerant, evacuate and replace.
	Expansion device clogged or covered with ice	CAUTION: Do not vent refrigerant to the atmosphere; use
		refrigerant recovery equipment.

40QNQ, 40QNC specifications

The Carrier 40QNC and 40QNQ are advanced rooftop packaged units designed for efficient heating and cooling in commercial applications. These units are particularly known for their reliability, versatility, and energy-efficient performance, making them a preferred choice for building owners and HVAC professionals alike.

One of the standout features of the Carrier 40QNC and 40QNQ units is their variable-speed technology. This innovative system allows for precise control of airflow and temperature, ensuring that indoor environments maintain consistent comfort levels while minimizing energy consumption. The variable-speed compressor operates at different speeds based on the cooling demand, leading to reduced energy costs and improved overall efficiency.

In terms of energy performance, both models boast high Seasonal Energy Efficiency Ratios (SEER) and Heating Seasonal Performance Factors (HSPF). This not only contributes to lower energy bills but also helps in meeting energy efficiency standards and regulations in various regions. This makes the 40QNC and 40QNQ ideal for environmentally conscious building projects aiming for sustainability.

Another notable feature is the advanced microchannel coil technology utilized in these units. Microchannel coils are lighter, more compact, and provide enhanced heat exchange capabilities compared to traditional coils. This technology contributes to a more efficient refrigerant flow and ultimately leads to improved performance and durability of the unit.

Moreover, both models come equipped with a robust control system that enhances user interface. With smart thermostat compatibility, users can easily manage their building's climate remotely, ensuring optimal comfort and energy management. These systems are designed to integrate seamlessly with building management systems (BMS), allowing for greater control and optimization.

The construction of the Carrier 40QNC and 40QNQ also deserves mention. The units are built with durable materials designed to withstand harsh weather conditions, providing longevity and reliability. Additionally, the low sound levels produced by these units make them suitable for noise-sensitive settings, ensuring comfort without disruptive operation.

In summary, the Carrier 40QNC and 40QNQ are exemplary rooftop packaged units that combine advanced technology, energy efficiency, and reliable performance. Their variable-speed operation, microchannel coil technology, and robust control systems make them ideal solutions for commercial heating and cooling needs, catering to both comfort and sustainability.