Between wrapping up the work year, Christmas prep, and hosting family for summer BBQs, December is a whirlwind, and the last thing you need is your air conditioner breaking down on a 28°C humid afternoon.
Whether you're in Hamilton, Cambridge, Te Awamutu, or heading out to the family bach in Raglan, December brings our first real taste of summer heat. It’s also the busiest time of year for HVAC technicians, meaning if your unit fails during the Christmas holidays, getting a callout can take time.
Before the holiday slowdown kicks in and the heatwaves arrive, take 10 minutes today to run through these 5 quick DIY checks.
1. The 2-Minute Filter Rinse (Clear Winter & Spring Dust)
Your filters have spent the last few months trapping winter dust, spring pollen, and pet dander. If they're clogged, your unit has to work twice as hard to pull air through, driving up your power bill and struggling to cool the room.
What to do: Pop open the front panel of your indoor unit, slide out the mesh filters, and take a look. If they look grey and furry, rinse them under lukewarm tap water or give them a gentle vacuum.
Pro tip: Make sure the filters are 100% dry before clipping them back in to prevent mold growth.
2. Clear Garden Overgrowth Around the Outdoor Compressor
Over spring, plants and weeds grow rapidly. If shrubs, grass, or stored outdoor gear have crept within 50cm of your outdoor unit, they choke its ability to dump heat out of your home.
What to do: Clear away any garden overgrowth, weeds, or lawn clippings around the outdoor box.
Why it matters: On a hot December day, an outdoor unit without proper breathing room will overheat and automatically shut down to protect its compressor - usually right when you need it most.
3. Check the Exterior Drain Line for Blockages
When your air conditioner runs on "Cool" or "Dry" mode during summer, it extracts litres of water from the air, which drains out through a small plastic pipe outside. Over spring, spiders, mud-dauber wasps, and garden debris love to nest inside these quiet pipes.
What to do: Locate the clear or white drain hose coming out near your outdoor unit and check that it's clear of dirt or webs.
Red flag: If you run your air con and water starts dripping down your inside wall instead of draining outside, turn the unit off immediately - your drain line is blocked.
4. The Remote Control & Battery Swap
There’s nothing worse than picking up the remote on Christmas Day to turn on the air con for your guests, only to find the screen blank or leaking battery acid.
What to do: Check the screen contrast. If the display looks faint, replace the AAA batteries now.
Pro tip: If you’re heading away for a few weeks over the holidays, pop the batteries out of the remote to prevent leaks while you’re out of town.
5. Run a 15-Minute "Stress Test" Before Christmas Day
Don't wait until a house full of Christmas guests arrives to find out your air conditioner is blowing warm air or making a strange rattling noise.
What to do: Turn your heat pump to COOL mode, set the temperature to 20°C, and let it run for 15 minutes.
What to check:
Is the air blowing out crisp and cold within 5 minutes?
Is the fan running smoothly without clicking or squeaking?
Is there a musty or stale smell? (A musty smell means bacteria or mold built up on the internal coils over spring and needs a professional clean).
What to Do If Something Isn't Right
If your unit passed all 5 checks, you're ready for a comfortable, cool summer! But if it failed the cold air test, smells musty, or makes unusual noises, it's best to get it looked at before the holiday break.
At Aircon Group Waikato, we help homeowners across Hamilton, Cambridge, Te Awamutu, Raglan, and the wider Waikato get their climate control systems summer-ready. Whether you need a quick pre-summer service or a free quote on upgrading your system before the heat sets in, our local team is here to help.
Call us on 0508 224 7687 or request a free quote online.
FAQs
Q: Why is my air conditioner blowing warm air during my test run?
A: First, double-check your remote is set to the snowflake icon (Cool) and not "Fan" or "Heat". If the settings are correct and the air is still lukewarm after 10 minutes, your unit may have a refrigerant leak or an electrical issue that requires a technician.
Q: How often should I clean the filters during a Waikato summer?
A: During peak summer (December through February) when your unit is running daily, we recommend rinsing your filters every 4 to 6 weeks. If you have pets or live near a dusty rural road, check them every 3 weeks.
Q: Is it normal for the outdoor unit to leak water in summer?
A: Yes! In cooling mode, condensation forms on the indoor unit and drains out through the exterior pipe near your outdoor unit. A steady trickle of water coming out of that pipe while the unit is cooling is a sign the system is working correctly.
Q: What should I set the air con to when hosting guests on Christmas Day?
A: Set the temperature to 21°C to 23°C on medium fan speed. When a room fills up with extra people, heat levels rise quickly - setting the unit early in the morning before the house warms up keeps the system running efficiently all afternoon.