HVAC & Refrigeration Troubleshooting Guides
Component-by-component field guides — the most common fault modes, how to confirm each on site, how to repair it, and the failure chain if it is left. Built from real service experience by R-Pro.
Solenoid Valve
Thermostatic Expansion Valve (TXV)
Filter Drier
Compressor
- Compressor Motor Burnout — Winding Short / Ground Fault
- Compressor Mechanical Failure — Bearing/Piston/Valve Damage
- Compressor Short-Cycling — Repeated ON-OFF
- Compressor Liquid Slugging — Liquid Refrigerant Ingestion
- Compressor Overheating — Abnormal Discharge Temperature
- Compressor Won't Start — No Response to Start Signal
Condenser
Evaporator
Four-Way Reversing Valve
- Four-Way / Reversing Valve Coil Burnout (Mode Switching Fails)
- Four-Way Valve Stuck in One Position (Mode Switch Fails)
- Four-Way Valve Stuck Mid-Travel (Severe Internal Bypass: HP↓ + LP↑)
- Four-Way Valve Internal Leak (Teflon Seat Worn)
- Four-Way Valve Pilot Tube Blocked (Coil OK but Slide Won't Move)
Suction Accumulator
Pressure Switch
- Low-Pressure Switch False Trip (Cuts Out at Normal Pressure)
- High-Pressure Switch False Trip (Cuts Out with Healthy Condenser)
- Pressure Switch Contacts Welded (Protection Lost — Most Dangerous)
- Pressure Switch Capillary Blocked (No Pressure Signal)
- Pressure Switch Diaphragm Cracked / Ruptured (Sensing Lost + Leak)
Electronic Expansion Valve (EEV)
- EEV Coil Winding Open Circuit (Stepper Motor Cannot Drive)
- EEV Stuck by Debris / Metal Chips (Needle Frozen)
- EEV Controller Signal Lost / Communication Fault (Valve Unresponsive)
- EEV Superheat Setpoint Misadjusted (Hunting / Capacity Loss / Liquid Slug)
- EEV Stepper Motor Lost Steps (Position Desync / Variable Performance)
Oil Separator
Liquid Receiver
- Receiver Overcharged — Liquid Backs Up in Condenser (HP↑ / Subcooling↑)
- Receiver Undercharge / Leak (Sight Glass Bubbles / Capacity Loss)
- Receiver King Valve Partially Stuck (Liquid Line Restriction — Mistaken for Undercharge)
- Receiver Outlet Liquid-Line Solenoid Fault (Pump-Down Failure / Supply Cutoff)
- Receiver Body Corrosion / External Leak
All of this, offline, in your pocket
R-Pro puts 600+ fault cases, AI diagnosis, voice memo, nameplate scan and job tracking on your phone — in 10 languages, working with no signal on site.
Start a 7-day free trial →