Inverter Basics
What type of compressor changes speed instead of turning on/off?
Inverter compressor
What valve changes the direction of refrigerant flow?
Reversing valve
What does VRV stand for?
Variable Refrigerant Volume
What type of communication is used between VRV units?
Communication bus / daisy chain
What is the first thing to check on any system?
Power
What component converts AC power to DC, then back to variable frequency AC?
Inverter drive / PCB
In heating mode, what coil becomes the condenser?
Indoor coil
What component controls refrigerant flow into each indoor unit?
EEV (Electronic Expansion Valve)
What happens if communication is lost between units?
System fault / shutdown
What do most VRV systems rely on for diagnostics?
Error codes
What is the main benefit of inverter
Energy efficiency / capacity modulation
What is defrost mode used for?
To remove ice from outdoor coil
What allows simultaneous heating and cooling?
Heat recovery system / branch selector box
What does DC stand for?
Direct Current
Why is checking airflow important
It affects system performance
What happens to amp draw as compressor speed increases?
It increases
What temperature condition typically triggers defrost?
Low outdoor temp + coil icing
What is used to split refrigerant piping to multiple indoor units?
Refnet / Y-joint
What tool is commonly used to diagnose inverter boards?
Multimeter
What happens if an EEV fails closed?
No refrigerant flow / low cooling
What type of signal controls compressor speed?
Frequency (Hz)
What happens to system pressures in heating vs cooling?
They reverse roles (high/low sides switch)
What must be configured so the system recognizes each indoor unit?
Addressing
What can cause erratic inverter operation?
Voltage issues / poor connections / bad board
Why shouldn’t you rely only on gauges with inverter systems?
System modulates—pressures vary constantly