Why you may discover a puddle of water under your car on hot days

In hot weather, many parked cars will have pools of water beneath their engines. What causes this issue – and should you be worried?

Parked car in summer

As Britain basks in a summer heatwave, you may find a puddle of water beneath your parked car, or water still dripping from the engine bay.

You might think the radiator has sprung a leak and the car is likely to overheat. However, it’s much more likely to be water dripping from the air conditioning system – and there’s nothing to worry about if so.

The excess water is caused by the air conditioning compressor working hard in hot weather. Due to thermodynamics, the unit itself can freeze over as it takes moisture out of the car.

Air con

When the car is parked and the air-con switched off, the ice on its surface melts. This is what causes the puddle under the car – and the hotter the weather, the bigger and more alarming-looking the puddle may be.

RAC spokesman Pete Williams revealed the motoring organisation had received lots of calls from drivers worried by pools of water under their cars.

“The advice is to check whether this is simply odourless water, or if it has coolant in, with a clear smell and colour. If it’s the former, there should be no need to worry.”

Hopefully, that’s panic over. Meaning it’s only the sunshine that will leave you hot under the collar during a heatwave. 

ALSO READ:

Heatwave life hack: how to clear your car of hot air

How to keep cool when driving in hot weather

How much does it cost to tax your car?

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Richard Aucockhttps://www.motoringresearch.com/
Richard is director at Motoring Research. He has been with us since 2001, and has been a motoring journalist even longer. He won the IMCO Motoring Writer of the Future Award in 1996 and the acclaimed Sir William Lyons Award in 1998. Both awards are run by the Guild of Motoring Writers and Richard is currently chairman of the world's largest organisation for automotive media professionals. Richard is also a juror for World Car Awards and the UK juror for the AUTOBEST awards.

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