When an air conditioner breaks down, most people call the first number they find. For a small split unit this sometimes isn't a problem; but for a VRF system, a chiller or a server room air conditioner, choosing the wrong service can be both expensive and dangerous. A wrong diagnosis leads to unnecessary parts replacement, and an incorrect refrigerant procedure leads to losing the compressor.
Whether you are a home user or a facility manager, the eight questions below help you get to know a technical service from the very first conversation.
Company and documents
01Which certificates do you hold?
A reliable technical service is a company that can document its activity and does not hesitate to share these documents when asked. The TSE Service Competence Certificate (HYB) shows that service is provided according to a defined standard. Certificates such as ISO 9001 quality management and ISO 45001 occupational health and safety show that the company keeps its processes on record.
For corporate work, a tax certificate, trade registry record and, where needed, work experience documents may also be requested. A company that avoids showing documents is one you will struggle to find anyone accountable at when a problem arises.
02Are your technicians F-gas certified?
Under the relevant regulations, technicians who work with fluorinated refrigerants must hold a certificate for this work. A certified technician knows how to recover refrigerant without releasing it into the atmosphere, and how to do leak testing and charging the correct way.
In addition, you should ask about professional qualifications for electrical work, working at height and occupational health and safety (OHS) training. A technician who climbs onto an outdoor unit on a roof without safety precautions means a risk of a workplace accident in your building.
03Do you have insurance?
The technical service's workers should be insured and, if possible, it should hold third-party liability insurance. Water damage, a falling part or electrical damage that may occur during installation or repair is covered by this insurance. Especially in corporate buildings and public institutions, this document should be part of the contract.
Diagnosis and way of working
04How do you diagnose a fault?
A correct diagnosis is made by measurement, not by guesswork. A good technician arriving at the unit first looks at the alarm history, then measures pressure, temperature, superheat, current and voltage. A service that says "the board is gone" or "the refrigerant has run out" without measuring often replaces parts unnecessarily.
Ask the technician to give you the values they measured in writing. These values allow comparison at the next breakdown and show what the diagnosis was based on.
05Do you give the price in writing before the work?
A reliable service, after identifying the fault and before starting work, states in writing the work to be done and its cost. If there is a survey or diagnosis fee, this should also be stated up front. Surprise line items after the job is done are the most common complaint.
For major repairs, for example compressor replacement, repair and replacement options are expected to be presented side by side with cost and duration. The decision is made by the equipment owner, not the service.
06What parts do you use, and what is your warranty?
It should be stated clearly whether the part to be used is original, equivalent, new or refurbished. Each option can be right in its place; what matters is that you are told and that it is written on the invoice.
Parts warranty and workmanship warranty are different things. What happens if an installed part fails, and whether the service will return free of charge if the same fault recurs soon after, should be discussed up front. If the device is under the manufacturer's warranty, it may be necessary to work with an authorized service so that the warranty is not voided.
Continuity and communication
Ask us these 8 questions too
Let us explain our documents, references and working method on site during the survey visit.
07How quickly can you arrive in an emergency?
Response time is the most decisive criterion when choosing a service, especially for critical areas. In a server room, hospital, cold room or production area, hours matter. You should ask whether the service is reachable outside working hours, on weekends and on holidays, and whether this service costs extra.
In corporate facilities, this time should be written in the contract in hours, not promised verbally. We explained in detail what other items a contract should include in our annual maintenance contract checklist article.
08Do you have references from similar work?
A company's success with split air conditioners does not mean it has the same experience with chiller or VRF systems. Ask whether it has worked on your type of equipment and in facilities of similar size. If possible, talk to a reference customer.
Companies that have worked in the field for many years, serve with their own technical team and have a spare parts supply network usually get faster results on complex faults.
Warning signs: when should you look at another service?
Some behaviors show in the first conversation that a service is not right for you. Making a definite diagnosis without measuring, avoiding giving the price in writing, not showing the parts they removed, and recommending repeated refrigerant charging without finding the leak are among the main ones.
Refrigerant charging without finding the leak means the same fault will reappear a few months later. Charging incompatible refrigerant into old R22 units is a serious safety risk; we explained this in our transition from R22 to R410A and R32 article.
How do you compare the quotes you receive?
The right way to compare quotes is not to look at the total price, but at what is provided for the same scope. The lowest quote is often the one with the narrowest scope.
In each quote, check whether the work to be done is listed item by item, whether measurement and a report are included, how parts and refrigerant are priced, and the warranty period. If one quote says "general maintenance" and another has a twelve-item work list, these two quotes are not describing the same service.
In corporate facilities, putting the quotes in a simple table helps: write the scope headings in the rows and the companies in the columns. Empty cells immediately show what is missing from which quote.
How does YOİ Mühendislik answer these questions?
YOİ Mühendislik has served across Türkiye from its Ankara base since 2009. We hold TSE HYB, ISO 9001, 14001, 45001 and 10002 certificates; our team has OHS training, and we also serve as an authorized LG service. In breakdown and repair calls we diagnose by measurement, give the price in writing before the work, and keep a directly reachable breakdown line for urgent situations.
Frequently asked questions
What is the TSE HYB certificate?
The TSE Service Competence Certificate (Hizmet Yeterlilik Belgesi, HYB) is a certificate issued by the Turkish Standards Institution showing that a company provides after-sales service in accordance with a defined standard.
What is the difference between an authorized service and an independent service?
An authorized service is one approved by the device manufacturer that can carry out warranty work. For devices whose warranty has expired, experienced and certified independent services can also be chosen with confidence; what matters is measurement-based diagnosis and a written warranty.
What happens if a service charges refrigerant without taking measurements?
Refrigerant charged without finding the leak is lost again soon, and an overcharge or undercharge can damage the compressor. Pressure measurement and leak detection should be done before any refrigerant work.
Is it normal to ask a technical service for a written report?
Yes. Especially in corporate facilities, a written report listing the values measured, the work done and the recommendations at every visit is both proof of maintenance and a record for later breakdowns.
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