Using Your Air Conditioner During Winter
Air conditioning systems are becoming increasingly popular across the UK. While radiators are still the norm, the comfort and flexibility modern units have led many homes and commercial premises to invest in them. As we move into winter, it’s easy to assume they’re only for hot days, after all, why cool a room when it’s frosty, rainy or foggy outside? In practice, many modern systems can do more than cooling, and understanding the right settings, limits and simple seasonal checks can help you use yours safely and sensibly throughout the colder months.
Quick summary
Who this guide is for: Property owners and facilities teams looking after a comfort-cooling or heat pump system through winter.
What it covers: When to use the unit in colder weather, how to prepare an outdoor condenser, what servicing to schedule, and when to call a qualified engineer.
Key takeaways: Use the correct mode for the season, stay within the manufacturer’s limits, keep outdoor sections clear and ventilated, and get professional help for faults, leaks or electrical issues.
Should You Use Your Air Conditioner In Winter?
Many people assume these systems become surplus during winter. In reality, a lot of modern installations can help regulate temperature year-round. If your setup includes heat pump capability, it can reverse its cycle to provide warm air indoors (subject to model limits and outdoor conditions). If you have a ductless system with zone control, you may also be able to set different temperatures in different rooms, so you only condition the spaces you’re actually using.
One practical point: heating performance can vary in colder weather, and some units will run defrost cycles to protect the outdoor coil. That’s normal, but if you’re unsure which mode you should be using (or you’re seeing unusual behaviour), it’s best to get a qualified engineer to check your settings rather than guessing.
Local Context: Bristol And The South West
In Bristol, Bath and across the South West, winter conditions are often damp and changeable. That mix of moisture, wind-driven rain and occasional cold snaps can increase the chance of debris build-up, blocked drainage and outdoor coil icing. Older building types (such as period terraces, stone properties and mixed-use premises) can also have ventilation quirks that affect comfort and humidity. If your outdoor unit sits in a tight courtyard, alleyway or exposed elevation, keeping airflow clear and condensate drainage protected becomes especially important.
If the property is listed, in a conservation area, or you share external walls with neighbours, it can also be sensible to take a cautious approach around siting, noise and appearance. When in doubt, get professional guidance before making changes to external equipment.
Preparing Your Outdoor Air Conditioner For Winter
If you have an external unit fitted and you’re expecting harsher weather, a sensible maintenance programme helps reduce the risk of problems during winter. These machines are significant investments for both residential and commercial clients, so it’s worth taking a few straightforward steps to protect the equipment and ensure it’s ready when warmer weather returns.
To maintain/prepare your AC unit for winter:
- Switch off the Power – Isolate the system before doing any checks to reduce the risk of electric shock. If you’re not confident with safe isolation, leave this step to a competent person or a qualified engineer.
- Clean Away External Debris – Clear away leaves, dust and organic matter so airflow isn’t restricted. This can also help discourage pests from nesting and reduce the chance of vents becoming blocked or damaged. Avoid forcing water into electrical areas.
- Perform a Visual Check – Look for obvious damage such as dents, cracks, corrosion, loose fixings or signs of oil staining. If you suspect a refrigerant leak, don’t try to “top it up”; refrigerants must be handled by appropriately qualified engineers. Getting a professional assessment early can prevent small issues from becoming expensive repairs.
- Consider Covering Your Unit – If the outdoor section won’t be used for extended periods, a suitable cover can help protect it from debris. Avoid airtight wraps that trap moisture, and never cover it in a way that blocks ventilation if the system may need to run during winter.
- Insulate the Pipework – Make sure any exposed pipework and drainage lines are protected against freezing. In very low temperatures, trapped water can freeze and expand, which may split vulnerable sections. If you’re unsure what should (and shouldn’t) be insulated on your installation, ask a professional for advice.
- Check Your Unit Regularly – Don’t ignore the outdoor equipment all winter. A quick weekly or fortnightly glance is usually enough to confirm nothing has been damaged by wind, storms or build-up around the intake/exhaust areas.
Book A Post-Winter Service
These systems can work hard, whether that’s year-round or mainly through summer, so regular servicing matters. The same applies to both commercial and residential installations: professional checks help keep performance consistent, support energy efficiency and reduce avoidable breakdowns. A proper annual visit can also pick up early signs of wear (such as blocked filters, drainage issues or electrical deterioration) and address them before they cause wider problems.
If you’d like a qualified engineer to confirm your unit is winter-ready (or to schedule a post-winter check), it’s best to arrange a professional service rather than relying on DIY inspections alone.
Minimum Operating Temperatures
Some units have a manufacturer-stated minimum operating temperature for certain modes (particularly cooling). Running the system outside those limits can affect how it operates and, in some cases, contribute to issues such as coil icing or poor lubrication of moving parts. The safest approach is to follow the guidance in your specific manual or ask an engineer to confirm the correct operating range for your model.
If you need to test performance during winter, for example, after a fault, avoid forcing the system to run in conditions it isn’t designed for. Where possible, carry out checks on a milder day and follow manufacturer instructions or professional advice to reduce risk to the equipment.
When To Call In The Professionals
Most units are designed to run reliably, but they are specialised machines, and some issues shouldn’t be handled as DIY. It’s sensible to keep contact details for experienced HVAC professionals to hand, especially if your property depends on the system for comfort, process cooling or stable temperatures.
If you notice common warning signs such as persistent leaking, ice build-up, unusual smells, repeated tripping, weak airflow or unexpected noise, a qualified engineer can diagnose the cause safely and get things back on track. This is particularly important where refrigerant circuits may be involved, as safe handling and compliance requirements apply.
Here at Controlled Climate, we have over 25 years of trading experience across air conditioning and heat pump systems. Our engineers support everything from design to installation and servicing, and we regularly work with properties across the region. If you’d like practical advice on winter settings, seasonal maintenance, or you want someone to inspect the outdoor unit for risk points, please contact our team, and we’ll point you in the right direction.
FAQs
Can I use my system for heating in winter?
If your installation includes heat pump capability, heating mode is designed for colder months. Performance depends on the model and outdoor conditions, and defrost cycles can be normal in damp or cold weather. If heating feels inconsistent, it’s best to have the settings and system health checked by a professional.
Should I cover the outdoor unit?
A purpose-made cover can help keep leaves and debris out when the unit won’t be used. However, avoid fully sealing it (trapped moisture can cause problems), and don’t cover it if the system needs to run; outdoor sections require airflow to operate safely.
How often should I service the unit?
Many installations benefit from at least an annual professional service, with commercial premises often needing more frequent checks depending on usage, environment and risk. Regular maintenance helps reduce breakdowns and supports efficiency.
Do I need planning permission for an outdoor unit?
Rules vary by property type and location. Some external changes may fall under permitted development, but listed buildings, conservation areas, flats and certain commercial settings can have additional restrictions. If you’re unsure, take a cautious approach and get professional guidance before proceeding.
What are the most common winter-related problems?
Typical cold-weather issues include debris restricting airflow, drainage/condensate problems, icing on coils when running outside recommended conditions, and weather-related damage to fixings or pipework. If you spot a leak, electrical fault or repeated icing, stop using the system and arrange an inspection.