How to replace the air handling unit in my R Series 20 SEER Single Zone Mini Split Heat Pump System?

Replacing the air handling unit in your R Series 20 SEER Single Zone Mini Split Heat Pump System is a complex task that should be performed by a licensed HVAC technician. The air handling unit, also known as the indoor unit or evaporator, is a critical component of your mini-split system. Replacing it incorrectly can lead to inefficiencies, refrigerant leaks, or damage to your system. Here is an overview of the process, but it's crucial to hire a professional for this job:

1. Hire a Licensed HVAC Technician:
The first and most important step is to hire a licensed HVAC technician with experience in mini-split systems. They have the expertise, training, and equipment necessary to safely and correctly replace the air handling unit.
2. Turn Off the Power:
Before any work begins, the technician will ensure that the power to the mini-split system is turned off. This is done by switching off the circuit breaker or disconnecting the power source to the indoor and outdoor units.
3. Remove the Old Air Handling Unit:
The technician will carefully remove the old air handling unit from the wall or ceiling where it is mounted. This may involve disconnecting electrical wiring, refrigerant lines, and drain lines. The old unit will be uninstalled while taking care not to damage any other components or refrigerant lines.
4. Prepare the New Air Handling Unit:
The new air handling unit should be the correct size and capacity for your R Series 20 SEER Single Zone Mini Split Heat Pump System. The technician will unbox and prepare the new unit, ensuring that it's clean and free from any defects.
5. Position the New Air Handling Unit:
The technician will position the new air handling unit in the same location as the old unit, ensuring that it's level and properly supported. The unit will be secured to the wall or ceiling using the appropriate brackets or hangers.
6. Reconnect Refrigerant Lines:
The technician will reconnect the refrigerant lines to the new air handling unit. Flare connections will be made, and proper torque will be applied to secure them. It's crucial to ensure that there are no refrigerant leaks.
7. Reconnect Drain Line:
The drain line will be reconnected to the new unit, ensuring that it slopes downward to allow proper drainage. If necessary, a condensate pump will be installed to lift and drain condensate if the unit is not near a suitable drain.
8. Connect Electrical Wiring:
The electrical wiring will be reconnected from the power source to the new air handling unit following the manufacturer's wiring diagram. The technician will ensure that all connections are secure and properly insulated.
9. Pressure Test and Leak Detection:
After making all the necessary connections, the technician will pressurize the system with nitrogen to check for leaks. Leak detection tools, such as electronic leak detectors or soap bubbles, will be used to verify that there are no refrigerant leaks.
10. Evacuate and Dehydrate the System:
The technician will use a vacuum pump to remove moisture and air from the refrigerant lines and the new air handling unit. This is essential to prevent performance issues and refrigerant contamination.
11. Recharge with Refrigerant:
Once the system is properly evacuated, the technician will recharge it with the correct type and amount of refrigerant as specified by the manufacturer's recommendations. Achieving the desired pressure and temperature levels is critical.
12. Test and Verify Operation:
After recharging the system, the technician will test the mini-split heat pump to ensure that it's operating correctly. They will check for proper cooling and heating, as well as verify that the system maintains the desired temperature and pressure levels.
13. Final Insulation and Inspection:
The technician will ensure that the new air handling unit is properly insulated to prevent heat gain or loss and condensation. They will conduct a final inspection of the entire system to ensure that all connections are secure, and there are no issues.


Remember that replacing the air handling unit in a mini-split system is a complex task that should only be performed by qualified professionals. Proper installation is crucial for the system's efficiency, performance, and safety. Always prioritize safety and hire a licensed HVAC technician for such tasks.