HVAC Refrigeration Guide — Refrigeration

How to Read Superheat and Subcooling Together

Sep 02, 2026

Superheat says low charge. Subcooling says overcharge. You don't have a gauge problem — you have a metering device or airflow issue. Learn how to read both numbers together using the four-quadrant diagnostic to pinpoint the real fault fast.

Tags: A2L refrigerants, fixed orifice, HVAC diagnostics, metering device, R-454B, refrigerant charging, refrigeration, subcooling, superheat, TXV

Danfoss Compressor & Control Failures: Diagnose Before You Replace

Aug 19, 2026

Danfoss compressor and control failures follow predictable patterns — a scroll that won't start, a reciprocating unit losing capacity, a pressure switch nuisance-tripping, or a TXV that won't hold superheat. This guide breaks down each failure category with diagnostic steps and the current OEM Danfoss part numbers (121L3070, MTZ160-4VI, 060-200191, 068U2287) to resolve them correctly the first time.

Tags: Compressor, Danfoss, HVAC, OEM Parts, Pressure Switch, R404A, R407C, Reciprocating Compressor, Refrigeration, Scroll Compressor, Troubleshooting, TXV

Heatcraft Bohn Larkin Unit Cooler Troubleshooting

Jul 19, 2026

HVACR techs: learn how to read Heatcraft IntelliGen alarm codes (AL01, AL06, ER25, ER26) before swapping parts. This guide covers the most common unit cooler faults — high box temp, door open alarms, connection-lost errors, and evaporator fan failure — with confirmed OEM part numbers for the two failures we see most: contactor failure (2259996) and evaporator fan motor failure (25322406).

Tags: 2259996, 25308301S, 25312601S, 25322406, AL01, AL06, alarm codes, Bohn, Chandler, contactor, ER25, ER26, evaporator fan, Heatcraft, high box temp, HVACR, IntelliGen, Larkin, not cooling, R026215300, refrigeration, troubleshooting, unit cooler, walk-in cooler

Condenser Fan Motor Diagnosis

May 13, 2026

A field-tested diagnostic guide for condenser fan motor failures — covering winding failure, bearing seizure, capacitor misdiagnosis, and OEM spec matching. Includes a symptom-to-cause table, step-by-step diagnostic sequence, and brand-specific notes for Trane, Heatcraft, York, and Nordyne.

Tags: bearing failure, commercial HVAC, condenser fan motor, Heatcraft, HVAC, motor diagnosis, Nordyne, OEM replacement, refrigeration, run capacitor, Trane, winding failure, York

Copeland Compressor Protection

May 06, 2026

Copeland compressor failures don't have to be a mystery. This field guide covers how to read CoreSense fault codes correctly, verify crankcase heater function before startup, and diagnose accumulator failures that drive repeat compressor failures — so you replace the right part the first time.

Tags: accumulator, compressor, compressor protection, Copeland, CoreSense, crankcase heater, discharge temperature, fault codes, field guide, filter drier, HVAC, liquid slugging, reciprocating compressor, refrigeration, scroll compressor, suction superheat, troubleshooting, vacuum procedure