5 Questions to Ask Any AC Installer Before You Sign Anything
Most bad AC installs could be avoided with five careful questions at quote stage. Here's exactly what to ask, and what the right answers sound like.
Most of the bad air conditioning installations I get called out to could’ve been avoided. Not because the installers were lazy, but because the homeowner didn’t know what to ask at quote stage.
Here are the five questions worth asking every single installer before you put a deposit down.
1. “What size unit are you specifying, and how did you calculate it?”
Sizing is the single biggest factor in whether your AC works well or drives you mad. Too small and it runs flat-out all day without ever cooling the room. Too big and it short-cycles — switching on and off constantly, which is noisy, inefficient, and shortens the unit’s life by years.
The right answer sounds like: “We calculated 3.5 kW based on your room being 28 square metres, west-facing, with single-glazed windows.”
The wrong answer sounds like: “We usually fit 5 kW in rooms this size.”
2. “Where exactly will the outdoor unit go?”
The condenser is the boxy unit that lives outside. Get its placement wrong and your neighbours will complain, your warranty might be void, and you’ll hear it humming from your bedroom.
Ask to walk outside with the installer. Look at the proposed location. Is it on a brick wall (good) or on a flimsy timber frame (bad)? Will it discharge hot air straight into a window or path? Is there enough clearance for the engineer to service it?
3. “How are you running the pipework?”
There are two refrigerant pipes, a drain line, and a power cable that have to get from the indoor unit to the outdoor unit. A good installer plans this route carefully — through cupboards, behind kitchen units, inside trunking that matches your walls.
A bad installer takes the shortest line and runs visible white trunking diagonally across your living room ceiling.
Insist on seeing the proposed pipe route on the survey.
4. “What’s included in the price, and what isn’t?”
Get this in writing. The classic upsells that appear after deposit:
- Extra refrigerant for longer pipe runs
- Scaffold hire if the outdoor unit needs roof access
- Electrical work if your consumer unit can’t handle the load
- “Optional” cover plate to hide pipework
- Commissioning paperwork for warranty registration
A proper quote names all of these explicitly — even if the answer is “not needed for your job”.
5. “What’s your aftercare process?”
Most manufacturers (Daikin, Mitsubishi, etc.) require annual servicing to keep your warranty valid. If your installer doesn’t offer that service, your warranty starts ticking down the day they leave.
The right answer: “Yes, we include 5 years of annual servicing — here’s what’s covered.” Anything less and you’re carrying the risk.
Bonus question: “Can I see two recent installations near me?”
Photos in a brochure mean nothing. A good installer should be happy to share contact details for two recent customers in your area. A two-minute phone call to one of them will tell you more than any quote PDF.
If you’re getting quotes for AC in a London property, book a free site survey with Climatemix. I’ll answer every one of these questions in writing, before you commit to anything.
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