What manufacturer service tools actually tell us
A Daikin D-Checker or Mitsubishi MELANS service tool plugs into the outdoor unit's communication port and streams live data — compressor frequency, expansion valve opening, refrigerant pressures, fan rpm, current draw on each phase, indoor/outdoor temperatures at every sensor. We log that data across a 20–40 minute run cycle, then compare against the manufacturer's known-good envelope. A failing expansion valve, a drifting sensor, a slipping inverter — they all show up on the trace before they show up on the remote. This is the difference between a diagnostic and a guess.
Electronic refrigerant leak detection
Above 2.5 tonnes CO₂-equivalent refrigerant charge, F-Gas regulations require annual leak detection by certified methods. We carry electronic refrigerant leak detectors (heated diode type, sensitive to <3g/year leak rates), fluorescent UV dye for borderline-suspect joints, and ultrasonic detectors for pressurised leak location on inaccessible pipework. Most leaks are at flare joints, brazed joints behind the indoor head, or at the outdoor unit Schrader valves — all repairable without replacing pipework if found early.
Thermal imaging — what an infrared camera reveals
An infrared thermal camera shows us coil surface temperatures across the evaporator and condenser, hot-spots on contactors and capacitors, uneven refrigerant distribution across the coil and unbalanced load across three-phase commercial systems. A blocked TXV or partially clogged coil shows as a cold patch surrounded by hot fins; a failing capacitor runs measurably hotter than its twin. This is non-contact, non-destructive, and often the fastest route to a hidden fault.
Electrical diagnostics — what we measure and why
Three things we measure on every diagnostic: capacitor microfarad value vs nameplate (a 30µF cap reading 24µF is failed even if it still spins the fan), insulation resistance on compressor windings (a megger test catches winding breakdown before the contactor trips), and current draw under load against the nameplate FLA. These three checks alone catch around 60% of intermittent electrical faults and almost all of the ones a non-specialist would call 'a glitch'.
Pre-purchase diagnostics — what buyers need to know
If you're buying a Dorset property with installed air conditioning, the system is rarely covered in a standard homebuyer's survey. A pre-purchase diagnostic from us tells you: age and remaining design life of each unit, refrigerant type (and whether it's a phased-out R22 system needing replacement), current refrigerant charge against nominal, condition of compressor, fan motors and controls, whether the warranty is live and transferable, and a written replacement cost estimate. Useful for price negotiation and useful for budgeting.
When diagnostics is the right starting point
Diagnostics is the right call when: a system has been repaired twice for the same fault; energy bills have risen without an obvious cause; a fault is intermittent and you can't reproduce it on demand; a fault appears only at certain temperatures or times of day; you're buying a property with installed air conditioning; you're inheriting a commercial site and want a baseline; you've had a brand-new install that 'doesn't feel right'. In every other case, a normal repair callout is the right starting point and almost always cheaper.
