-
- About Us
- Cooperation
- News
- Offer
- E-shop
- Contact
- TRACK FINDER
- WYSZUKIWARKA SZYB
- Kategorie produktowe
-
ALL CATEGORIES
-
-
-
-
-
-
SLEW SYSTEM
-
-
-
-
-
AXLES
- TIE RODS
- KIT SPIDER FOR DRIVE SHAFTS
- DIFFERENTIAL
- MOUNT THE KNUCKLE
- KIT SPIDER FOR AXLE SHAFTS
- HUB / GEAR REDUCTION
- PROPSHAFTS
- SOLENOID VALVES / COILS
- FLANGES / COUPLING YOKES
- BEARINGS
- BUSHES / WASHERS MOUNT AXLE
- AXLE / DIFFERENTIAL HOUSING
- DRIVESHAFTS / CENTER JOINTS
- BOLTS / NUTS / STRAPS
- LOCK / CIRCLIP / CLIP
- CROWN WHEEL AND PINIONS
- SEALS
- OTHERS
-
-
-
-
-
-
-
-
ENGINE
-
-
-
-
-
COILS / SOLENOID VALVES
-
SWIVELS / TURNING JOINTS
-
PUMPS / STEERING VALVES / MOTORS
-
-
-
VALVES
-
HYDRAULIC HOSES / PIPES
-
RAMS
-
ACCUMULATORS
-
QUICKHITCHES
-
-
-
BOLTS / NUTS / WASHERS
-
PUMP DRIVESHAFTS
-
SEALS VALVES / PUMPS
-
OTHERS
-
-
-
-
-
-
-
TIMING
-
EQUIPMENT
-
-
LUBRICATION SYSTEM
-
-
INDUCTION / EXHAUST SYSTEM
-
SEALS / GASKET SETS
-
ENGINE MOUNTING
-
SERVICE TOOLS
-
-
-
-
-
-
STABILIZERS
-
-
-
-
-
-
FUSES / FUSE BOXES
-
RELAYS / FLASHERS
-
REVERSE ALARM
-
-
HEATERS / BLOWERS
-
BATTERY ISOLATER SWITCH
-
-
-
-
-
OILS
-
FLUIDS
-
-
-
PAINTS
-
-
-
-
-
-
-
GLASS / CAB GLAZING
-
-
-
RUBBER SEALS - GLASS
-
ASSEMBLY KITS / ADHESIVES
-
-
-
-
-
ADAPTERS
-
BOLTS / LOCKS
-
-
-
-
HYDRAULIC INSTALLATIONS
-
TOEPLATES
-
TOOTH RIPPER
-
-
-
HYDRAULIC HAMMERS / TOOLS
-
PLOWS
-
QUICKHITCHES
-
FORKS
-
-
-
EARTH DRILL / AUGER
-
SWEEPER / COMPONENTS
-
SWINGOTILT / PLATFORMS
-
-
-
-
-
ACCESSORIES
-
DECAL / STICKERS
-
-
-
GADGETS
-
CLOTHES
-
FAN ZONE
-
-
-
- SPARE PARTS SUITABLE FOR
- JCB
- CAT
- VOLVO
- KOMATSU
- CASE
- NEW HOLLAND
Cab Heating and Air Conditioning Failure: A Step-by-Step Diagnosis
Cab Heating and Air Conditioning Failure: A Step-by-Step Diagnosis
Comfort That Translates to Productivity
A functional heating, ventilation, and air conditioning (HVAC) system in a construction machine's cab has long ceased to be a luxury and is now an absolute necessity. Working in 30°C heat or sub-zero temperatures drastically reduces an operator's concentration, efficiency, and safety. A failure of this system is not just a matter of discomfort; it's a real problem that can halt work. In this comprehensive guide, we will conduct an in-depth diagnostic analysis of the entire HVAC system in a typical JCB, CAT, or Volvo machine to show what fails and how to diagnose it.
Part I: The Heating System – When It's Cold in the Cab
The heating system in a construction machine is a relatively simple design that utilizes "free" heat from the engine.
How Does the Heater Core Work?
The heater core is a small radiator located inside the dashboard. Hot coolant from the engine's cooling system flows through its core, and the cab's blower fan pushes air through it. The air heats up and is directed into the cab. Simple, but susceptible to several common failures.
Anatomy of a Heating Failure:
- Problem 1: Air Lock in the System. This is the most common and easiest cause to fix. If there is air in the cooling system (e.g., after a coolant change), it can get trapped at the highest point, which is often the heater core, creating an air pocket and blocking the flow of hot coolant. A symptom can be heating that only works at high engine RPMs.
- Problem 2: Clogged Heater Core. If water was used in the cooling system for years instead of proper coolant, scale and rust build up inside the heater core. They clog the thin passages, preventing flow. The only remedy is often to replace the heater core.
- Problem 3: Faulty Heater Valve or Thermostat. Many machines have a valve that regulates coolant flow through the heater core. If it gets stuck closed, there will be no heating. Similarly, if the main engine thermostat is faulty and the engine doesn't reach operating temperature, the heating will be very weak.
Part II: The Air Conditioning System – When It's Hot in the Cab
The A/C system is a much more complex, closed-loop pressure system that works on the principle of a refrigerator.
How Does Air Conditioning Work?
In simple terms, refrigerant circulates in a loop, changing state and transferring heat from inside the cab to the outside. The key components are:
- Compressor: The "heart" of the system, driven by a belt from the engine. It compresses the refrigerant gas, raising its pressure and temperature.
- Condenser: Located at the front of the machine, in front of the engine radiator. Here, the hot refrigerant gas releases heat to the ambient air and condenses into a liquid.
- Receiver-Drier: A small reservoir that filters the refrigerant and absorbs any residual moisture.
- Expansion Valve: Drastically reduces the pressure of the liquid refrigerant.
- Evaporator: This is a "small radiator" inside the cab. The low-pressure, ice-cold refrigerant evaporates in it, absorbing heat from the air being blown into the cab.
Anatomy of an A/C Failure:
- Problem 1: A Leak (The Most Common!). The A/C system is under constant pressure. Vibrations and temperature changes in a construction machine cause the o-ring seals at connections to harden and flexible hoses to perish over time, leading to a slow refrigerant leak. Diagnosis: The most effective method is to add a UV dye to the system and inspect all connections with an ultraviolet lamp. A greenish-yellow glow will pinpoint the leak.
- Problem 2: Compressor Failure. This can be an electrical failure (burnt clutch coil) or a mechanical failure (seizure). Seizure is often the result of running the system with low refrigerant and oil.
- Problem 3: Clogged Condenser. Mud, dust, and leaves block the condenser fins, preventing heat dissipation. The system is unable to cool down, pressure rises, and a safety switch shuts the system off.
The Common Denominator: Blower Fan, Control Panel, and CABIN FILTER
The Crucial Role of the REDX Cabin Filter
The cabin filter is an often-ignored but absolutely critical component. Its job is to protect the operator's health from dust, pollen, and allergens. But it also has a huge impact on the HVAC system's performance! A clogged filter drastically restricts airflow. In heating mode, this results in poor heating. In A/C mode, it can lead to evaporator icing and a complete blockage of airflow. Regular replacement with a high-quality product, like REDX filters, is fundamental.
- Blower Fan Failure: If there is no airflow at any speed, the cause could be a blown fuse, a faulty switch, or a burnt-out blower motor. If only the highest speed works, the culprit is usually a burnt-out blower motor resistor.
- Control Panel Failure: If the panel is unresponsive and the blend doors are not working, the problem could be with the panel itself, its power supply, or the actuators that control the flaps.
FAQ - Frequently Asked Questions
1. Why does my A/C, recharged in the spring, stop working in the middle of summer?
This is a classic symptom of a small leak. The system slowly loses refrigerant, and when the pressure drops below a minimum threshold, a pressure switch turns off the compressor to protect it from seizing. "Recharging" without finding and fixing the leak is a waste of money.
2. There is an unpleasant, musty smell coming from the vents. What is the cause?
This is mold and bacteria growing on the moist A/C evaporator. It requires a professional system cleaning and a mandatory replacement of the cabin filter.
3. The heating works, but it's very weak. The cabin filter is new. What should I check?
First, check if the engine is reaching its proper operating temperature (around 90°C / 195°F). If it is, and both hoses going to the heater core are hot, the problem is most likely a contaminated or clogged heater core.
Ensure Your Comfort All Year Round. Take Care of Your HVAC System.
Regular service and cleanliness are key to the reliable operation of your heating and air conditioning. Our offer includes everything you need for service: from high-quality REDX cabin filters, to heater cores, A/C condensers, receiver-driers, and blower motors. Contact us, and we will help you select the right parts!
Related posts
WE OFFER PRODUCTS OF THE BEST BRANDS


















ul. Podkarpacka 57A, 35-082 Rzeszów
NIP: 813-352-97-49 REGON: 180286726
Opening hours
Telephone support - Monday - Friday (8:00 AM – 5:00 PM)
Order pick-up - Monday - Friday (8:00 AM – 4:30 PM)
[email protected]
[email protected]
Gadu-Gadu communicator
GG: 4185846 - Daniel
+48 17 864 31 00
+48 17 864 00 24
+48 17 864 25 96
Mobile phone
+48 607-700-547
+48 695-944-818
+48 691-330-531
+48 690-906-751
Fax
+48 17 864 31 20
