Many drivers assume that air conditioning is only needed in summer. Once temperatures drop, the AC button is often ignored for months at a time. While this may seem harmless, leaving your car’s air conditioning system unused throughout winter can have unintended consequences. Understanding how the system works and why winter use still matters can help you avoid unnecessary repairs and maintain comfort year-round.
How does your car’s air conditioning system really work?
Your car’s air conditioning system is not just about cooling the cabin. It plays an important role in managing air quality and moisture, regardless of the season. The system relies on a compressor, refrigerant, seals, and hoses that must remain lubricated to function correctly.
When the system operates, refrigerant circulates through the components, carrying oil that lubricates seals and internal parts. If the system is left unused for long periods, this lubrication does not occur. Over time, seals can dry out, increasing the risk of leaks and reduced performance when the system is eventually switched back on.
So, what happens if you leave your AC off all winter?
Leaving your air conditioning switched off throughout winter will not cause immediate damage, but it can contribute to gradual deterioration. The most common issue is seal degradation. Rubber seals rely on regular contact with lubricated refrigerant to remain flexible. Without use, they can harden or crack, allowing refrigerant to escape.
Loss of refrigerant reduces system efficiency and can place strain on the compressor when the system is reactivated. In some cases, this can lead to costly repairs that could have been avoided with simple preventative use.
Another potential consequence is moisture build-up within the system. Air conditioning systems help remove humidity from the air. When unused, moisture can accumulate, increasing the risk of mould and unpleasant odours when the system is turned back on.
Why is air conditioning useful in winter?
Although it may seem counterintuitive, air conditioning has a valuable role in winter driving. One of its most important functions is rapid demisting and defogging of windows. The AC system removes moisture from the air far more effectively than warm air alone, helping you maintain clear visibility in damp or cold conditions.
Modern vehicles often activate the air conditioning automatically when you select the windscreen demist setting, even if the temperature outside is low. This is because dry air clears condensation faster, improving safety and comfort.
Using the AC periodically during winter also keeps internal components moving and lubricated, helping to preserve the system’s long-term reliability.
How often should you use your AC in winter?
You do not need to run your air conditioning constantly during winter to keep it healthy. Using it for around ten minutes once a week is usually sufficient to circulate refrigerant and lubricate seals. This can be done during normal driving, ideally with the fan and temperature set comfortably rather than at maximum cooling.
If your vehicle automatically engages the AC during demisting, this regular use may already be happening without you realising. However, it is still worth being conscious of AC operation, particularly if you tend to drive short distances.
What are the signs your AC system may be suffering from lack of use?
If your air conditioning has been unused for several months, there are a few signs that may indicate developing issues. Weak airflow, unpleasant smells when the system is switched on, or reduced cooling performance in warmer weather can all point to problems linked to inactivity.
You may also notice that the system takes longer than expected to demist windows, which can suggest reduced efficiency or moisture build-up.
Addressing these symptoms early can help prevent more serious damage, particularly to the compressor, which is one of the most expensive components to repair or replace.
So, is it damaging to leave your AC system switched off all winter?
Leaving your air conditioning off all winter increases the risk of wear, leaks, and reduced performance over time. Regular, light use during colder months keeps the system lubricated, helps control moisture, and ensures it is ready when warmer weather returns.
Here at MRS Heat Transfer we are radiator, car heater, oil cooler, and air conditioning experts, and we have the skills, knowledge and expertise to resolve any air conditioning or car heater problem. Why not get in touch today to find out more?