Step-by-step refrigeration diagnostics
Interactive, safety-first decision trees that walk you from a symptom to the root cause on real rack systems. Free to run.
Case Not Holding Temperature
Walk through a display case or walk-in running above product temperature.
High Head / Discharge Pressure
Diagnose a rack running high discharge pressure or tripping high-pressure safeties.
Compressor Won't Start
A compressor is commanded on but is not running.
Compressor Short Cycling
A rack compressor starts and stops rapidly.
Low Suction Pressure
The suction group runs below setpoint and compressors can't satisfy.
Oil Failure / Low Oil
Diagnose oil-safety trips and low oil on the parallel rack.
CO2 High-Side / Gas Cooler Pressure
Transcritical CO2 rack running high-side pressure above the optimum target.
CO2 Flash Tank / Receiver Pressure
Intermediate receiver pressure off target, upsetting liquid feed and MT suction.
CO2 Standstill Pressure Rising
System off and pressure climbing toward relief — protect the charge.
CO2 Rack Inefficient in Hot Weather
High-side pressure and energy look high on a hot day — is it normal transcritical operation or a fault?
CO2 Gas Detection Alarm
The store or plant-room CO2 detector is alarming — handle it as a safety event first.
R-290 Self-Contained Case Not Cooling
Diagnose a plug-in / self-contained display case on R-290 (propane) that isn't holding temperature — safety first, then airflow, electrical, and sealed system.
R-290 Case Condenser Fan Not Running
Diagnose a self-contained R-290 (propane) case where the condenser fan has stopped or slowed, driving up head pressure and warming the case.
R-290 Case Controller / Config Fault
Walk a self-contained R-290 case that's off temperature or alarming when the sealed system and fans check out — setpoint, probe, and defrost configuration.
Danfoss AK-PC: Discharge Pressure High (3411 / 3431)
Walk a Danfoss AK-PC pack controller high discharge pressure / HP switch alarm from the display code to the root cause.
Danfoss AK-PC: Suction Pressure Low (3400)
Diagnose a Danfoss AK-PC low suction pressure alarm — charge, restriction, feed, or a bad transducer.
Danfoss AK-PC: Oil Level Low (3500)
Trace a Danfoss AK-PC low-oil alarm through the oil-management chain before adding oil.
Danfoss AK-PC: Discharge Temperature High (3302)
Diagnose a Danfoss AK-PC high discharge-temperature alarm — sensor, injection, pressure ratio, or the compressor.
Emerson E2: Phase Fail
Work an Emerson E2 (RX/BX) Phase Fail advisory from the panel to the electrical root cause.
Emerson E2: Compressor Proof Failure
Diagnose an Emerson E2 Compressor Proof Failure — commanded on but no run proof.
Emerson E2: Alarm Limit Exceeded
Split an Emerson E2 'Alarm Limit Exceeded' advisory into the real refrigeration cause vs a bad sensor.
Emerson E2: Board / Unit Offline
Bring an offline Emerson E2 I/O board back online — power, RS485 network, and addressing.
Danfoss AK-SC 355: I/O Network Failure
Bring a controller / I/O board back online on the Danfoss AK-SC 355 site network — power, rescan, wiring, addressing.
Danfoss AK-SC 355: Sensor / Point Offline
Diagnose an AK-SC 355 offline / out-of-range monitored point — configuration, wiring, sensor, or input.
Danfoss AK-SC 355: High / Low Temperature Alarm
Split an AK-SC 355 routed temperature alarm into a real refrigeration issue vs a bad sensor / setpoint.
Danfoss AK-SC 355: Stepper Valve / Output Fault
Diagnose an AK-SC 355 variable output / stepper valve that isn't controlling.
Emerson Einstein: Phase Loss / Phase Fail
Work an Emerson Einstein Phase Fail advisory from the panel to the electrical root cause.
Emerson Einstein: Compressor Proof Fail
Diagnose an Emerson Einstein Compressor Proof Fail — commanded on but no run proof.
Emerson Einstein: I/O Net Board Offline
Bring an offline Emerson Einstein I/O Net board (16AI / 8RO / 4AO) back online — power, RS485 network, addressing.
Emerson Einstein: Case / Product Temp Alarm
Diagnose an Emerson Einstein case / product temperature alarm — sensor, defrost, feed, or suction.
VRF: Indoor–Outdoor Communication Error
Track a VRF/VRV communication error (e.g. Daikin U4/UF, Mitsubishi E6/6607, LG CH04) from the code to the faulted link.
VRF: Poor or No Cooling / Heating
Split a VRF capacity complaint into a single-zone valve issue, a mode conflict, a charge problem, or the inverter not ramping.
VRF: High-Pressure Trip
Work a VRF outdoor high-pressure trip — airflow, valves/charge, indoor flow, or a false sensor.
VRF: Inverter / Compressor Drive Fault
Diagnose a VRF inverter overcurrent / DC-bus / IPM fault — supply, compressor, board cooling, or the PCB.
Glycol Pump: Running but No / Low Flow
The glycol circulator runs but the loop isn't getting flow — valves, air, rotation, or a worn pump.
Glycol Pump: Noisy / Cavitating
Trace gravel-like pump noise and swinging flow to a suction/NPSH problem before it wrecks the pump.
Glycol Pump: Motor Tripping / High Amps
Diagnose a glycol pump tripping its overload/VFD — viscosity, mechanical, or electrical.
Chiller: Not Holding Chilled-Water Setpoint
Work a chiller that can't hold leaving-water temp — flow, head, charge, or capacity/fouling.
Chiller: High Condenser Pressure Trip
Diagnose a chiller high-head/high-pressure trip on air-cooled vs water-cooled machines.
Chiller: Low Evap Temp / Freeze Trip
Trace a chiller freeze / low-evaporator-temperature trip before it splits the barrel.
Chiller: Centrifugal Surge
Diagnose centrifugal chiller surge — lift, low load, vanes/VFD, or sensing.
Cooling Tower: Poor Heat Rejection (High Approach)
Diagnose a cooling tower not rejecting design heat — airflow, distribution, or fill.
Cooling Tower: Fan Noise / Vibration
Trace cooling-tower fan vibration/noise across belt, gear, blades and motor.
Cooling Tower: Excessive Water Loss
Diagnose high makeup usage — overflow, drift, over-bleed, or leaks.