Cab air conditioning is treated as a luxury until it fails, and then it becomes a production issue: an operator in a hot, humid cab makes mistakes and stops early, and that costs far more than the repair. The system is also one of the most commonly misdiagnosed on an excavator, because the symptom — the cab is not cold — can come from any of five separate failures, and replacing the compressor solves only one of them. Guangzhou Shenyue Machinery Technology Co., Ltd. supplies these parts daily and this guide sets out a diagnostic order that avoids the expensive guess.
Work from the whole circuit, not the compressor
A refrigeration circuit has four functional parts on the machine: compressor, condenser, expansion device and evaporator, connected by lines and controlled by pressure switches. Cooling loss can come from a weak compressor, a condenser that is blocked with dust and cannot reject heat, an expansion valve that is stuck, an evaporator that is frosted or contaminated, or simply a low refrigerant charge from a slow leak. Because a compressor is the most expensive and the most visible part, it is the one most often replaced first — and the one most often replaced unnecessarily.
The diagnostic order that saves money
Begin with the simplest checks. Confirm the compressor clutch engages when cooling is requested; if it does not, the fault is electrical or a pressure switch, not the compressor itself. Clean the condenser, which on an excavator is typically mounted where dust and chaff collect, and confirm the cooling fan works at both speeds. Measure high-side and low-side pressures with a manifold gauge set and compare them with the specification — the pattern of the two readings identifies the fault far more reliably than the parts catalogue does. Only then look at the expansion valve and compressor. On a machine where the compressor does run but pressures are low on both sides, the fault is usually charge or expansion valve rather than the compressor.
| Reading or symptom | Most likely cause |
|---|---|
| Clutch does not engage | Switch, relay, fuse or low pressure cut-out |
| High side high, cooling weak | Condenser blocked or fan not running |
| Both sides low | Low charge or leaking circuit |
| High side very high, low side low | Expansion valve or restriction |
| Evaporator ices over | Expansion valve or thermostat control |
Dust is the excavator's speciality
An excavator works in conditions that destroy a car's A/C: fine dust that packs a condenser, vibration that loosens lines and mounts, and long idle periods where the circuit is not exercised. The condenser in particular needs cleaning as routine maintenance, not as a repair, and the compressor's mounting and belt condition deserve a look at the same time because a loose mount or a glazed belt causes noise that is misread as compressor failure. On our list the cooling and air-conditioning range covers condensers, evaporators, brackets and lines alongside the engine-side cooling parts that share the same airflow.
Heating is a separate circuit and fails separately
The cab heater draws heat from the engine coolant through a small radiator and a blower, with its own valve and lines. A cab that will not heat in winter is not an A/C fault at all: check coolant level and the heater valve, then the blower and its resistor. On machines that work in cold climates this matters as much as cooling does in the tropics, and the parts are simple and inexpensive — which is why leaving a cold cab unrepaired in a cold market is difficult to justify.
How we supply
Guangzhou Shenyue Machinery Technology Co., Ltd. has specialised in Kobelco parts since 2007, with 4 warehouses over 1000 m² in Guangzhou, 3,000+ part types on the shelf and 100,000+ part numbers available to order through original supply channels. Shenyue is an independent supplier and is not an authorized dealer of Kobelco Construction Machinery Co., Ltd.; for Kobelco, Hino, Isuzu, Yanmar, Cummins, Kawasaki, Nabtesco, KYB and KPM we supply genuine parts ordered through original supply channels alongside quality replacement alternatives, at prices close to agent level, and the five brands we hold formal authorization for — Mitsubishi, Garrett, TONGMYUNG, Marusan and NIKURA — are named on every quotation. Browse the cooling and A/C range and the SK260LC model page; Kobelco's published machine history at kobelco.co.jp is a useful cross-reference for class and generation.
Frequently Asked Questions
My Kobelco cab is not cold — do I need a new compressor?
Not necessarily, and replacing it first is the most expensive mistake in this system. Check that the clutch engages, clean the condenser, and measure high and low side pressures before condemning the compressor. Many 'failed' compressors are actually low refrigerant charge, a blocked condenser or a faulty expansion valve.
How often should the A/C condenser be cleaned?
Treat it as routine maintenance in dusty conditions, not as a repair. A condenser packed with dust cannot reject heat, which raises high-side pressure and weakens cooling. Clean it whenever the machine's other coolers are cleaned.
Why does my cab heater not work when the A/C does?
They are separate circuits sharing only the blower housing. Heating draws on engine coolant through a small radiator and valve, so a cold cab usually means low coolant, a stuck heater valve or a failed blower resistor rather than any refrigeration fault.
Can I fit universal A/C parts to a Kobelco?
Compressors, expansion devices and pressure switches are matched to the machine's circuit and its mount, so universal parts often fit physically and perform badly. Quote from the machine plate and the component nameplate, and Guangzhou Shenyue Machinery Technology Co., Ltd. will confirm the correct number and its grade.