HVAC fault diagnosis and repair
On-site HVAC fault diagnosis with measuring equipment, prioritisation by criticality and repair in the same visit wherever possible.
When HVAC fails in a hotel, an office or a residence, the problem stops being technical and becomes operational: complaints, rooms that cannot be let, spaces that have to be closed. This service is designed for maintenance and building managers who need a reliable diagnosis and a repair done properly, not a temporary fix that fails again a few weeks later.
Common faults in commercial buildings
Some symptoms come up again and again:
- Units that run but do not cool or heat enough, often due to low refrigerant, dirty coils or insufficient airflow.
- Shutdowns on high or low pressure in the refrigerant circuit.
- Drips and overflows from blocked condensate drains or failed condensate pumps.
- Fault codes on indoor or outdoor units, sometimes caused by communication errors between them.
- Noise and vibration from fans or compressors.
- Tripped protective devices or power supply faults.
The same symptom can have several causes, which is why components should not be replaced without a diagnosis first.
How the call-out is organised
Faults are prioritised according to the contract and the criticality of the affected equipment: a failure in the central plant serving the whole building is not handled in the same way as a fault on a single unit. On site, the technician diagnoses the problem with measuring equipment, checking circuit pressures and temperatures, electrical draw, and the state of sensors and communications. Wherever possible, the repair is completed in the same visit. If a spare part is needed, it is planned according to the equipment and its availability, and you are kept informed of the options in the meantime. Our office hours are Monday to Friday, 9:00 to 18:30; night or out-of-hours work can be arranged in advance. We work both for clients with a maintenance contract, whose service conditions are defined in each contract, and on one-off repairs without a contract.
Adjust, repair or replace
After diagnosis, you should be able to decide with full information. We therefore distinguish between an adjustment (set points, configuration, cleaning), the repair of a specific component and the replacement of the unit when repair is not worthwhile because of age, parts availability or efficiency. On older units running on phased-out refrigerants, leak repairs may be limited, and it is better to know that before investing. When replacement is the sensible option, it is worth treating it as a small installation project and choosing a unit suited to how the space is used today, which has often changed since the original was fitted.
When the cause is electrical
Many HVAC faults originate in the electrical installation: unstable voltage, incorrectly sized protective devices, deteriorated connections or overloaded distribution boards. Because we also work on electrical installations and boards, the diagnosis can cover both sides without passing the problem to another contractor or losing time on coordination. A common example is a compressor that trips on thermal overload: it looks like an equipment fault, yet it may be caused by a voltage drop on start-up or a worn contactor in the board. Measuring before replacing avoids changing parts that were in good condition.
From corrective to preventive
A recurring fault is a warning sign. Every intervention is recorded, so patterns can be spotted: the same unit failing every summer, drains that keep blocking or filters clogging sooner than expected. When these patterns appear, the sensible step is to review the preventive plan or bring the equipment under a technical maintenance contract. Our blog explains how your building warns you before it fails. In sectors such as hotels, where a room without working air conditioning is a room that cannot be sold, prevention has a direct effect.
Information that speeds up diagnosis
- Make, model and location of the unit, or a photo of its rating plate.
- Fault codes shown on the controller or the unit.
- When the fault occurs: all the time, at certain hours or only in extreme temperatures.
- Areas affected and the impact on operations.
- Recent work on the system and a contact person with access to the equipment.
Related content
By area
Frequently asked questions
Can you give me a repair cost over the phone?
Not reliably, as a rule. The same symptom can have very different causes, from a blocked drain to a damaged compressor. The make, model, fault codes and a description of the problem help us prepare the visit, but the repair can only be assessed properly after on-site diagnosis.
Do you repair equipment from any manufacturer?
We diagnose and repair HVAC equipment from a range of manufacturers and system types. The specific repair depends on the availability of spare parts for that model, which is planned after diagnosis. For older or discontinued units, we assess whether repair is reasonable compared with replacement.
What should I do while waiting for the technician?
Note down any fault codes before resetting the unit, as they may be lost on reset. If there is a leak, protect the area and, if it is safe to do so, switch off the affected unit. Avoid repeatedly restarting equipment that trips on high pressure, as this can make the problem worse. Also check whether one unit or several are affected.
Why is the air conditioning running but not cooling?
The most common causes are dirty filters or coils restricting airflow, low refrigerant due to a leak, fans not reaching their speed, badly placed sensors or incorrect set points. In central systems, it may also come from the chilled water plant or poor hydraulic balancing. On-site readings make it possible to tell these causes apart.
Who decides whether to repair or replace a unit?
The building manager, using the information from the diagnosis: the unit's condition, the extent of the repair, parts availability, the refrigerant it uses and its energy use compared with current equipment. Our role is to set out the options clearly, including temporary measures where a replacement needs time to plan.
Describe the fault
Tell us about the equipment, the symptoms, any fault codes and the impact on operations so we can prepare the diagnosis.
Report a fault