Water Leak From Under Car When Air Conditioning Is On

It can be quite concerning to see that puddle underneath your car. It conjures up thoughts of expensive repair bills and time without your vehicle.  This brief article looks into what can cause a water leak under your car when the Aircon is on.

Water coming from beneath a car is typically condensation from the air conditioning or the exhaust.  Water close to the rear of the engine bay is probably condensation from the air conditioning system. There is no need for concern as this is meant to happen

To work correctly, the air-con has to pull the humidity out of the air. This leads to moisture being produced. What you are seeing is the result of that being exited from your aircon system through a hose under the hood of your car.

To check that this is where the water is coming from. Open the hood and look inside close to the windshield. You should see a small black hose poking through the fire break of your car on the passenger side.

When the air-con is on, this will leak water from your air-con system. 

No water underneath your car when the AC is on is actually a bad thing. It indicates a blocked hose that will allow water to back up into your car’s cabin, soaking the passenger carpet. 

Another way of checking is to turn your air-con off and see if you still have fluid leaking from your car.  

If you have no leaks, but everything else is the same apart from your air-con being off, you can be sure that your aircon is causing the water underneath your car and everything is fine.

A leak with the aircon off indicates a different car system is leaking.

How Much Water Should Leak From A Cars AC?

When it’s humid weather, we are more likely to have our air-con turned on; more humidity is being taken out of the air before it enters your cabin. 

More humidity in the air results in more water evaporation being produced by your car’s AC. 

Just to reiterate, there is no need to worry. You don’t have to top any fluid up. This process is a natural reaction to the air-con working correctly. 

People sometimes incorrectly believe that what they are losing is the Freon coolant gases. 

In fact, Freon at normal temperature is a gas and would not create a puddle underneath your car.

Leaking might be the wrong word to use as it implies that something is wrong when in fact, everything is working as it should.

Water underneath your car indicates your aircon system is working just fine.

Other Leaks Under The Car When The AC Is On

When your AC is on, your engine is asked to work harder as the serpentine belt must turn the AC compressor to get the process of delivering the cold air you need in your cabin started.

When your engine is being asked to work harder, it is also creating more heat, which can add pressure to the coolant system. This added pressure can increase the likelihood of coolant leaks, so there is a possibility it could create puddles underneath the front of your car.

 A good indicator that coolant is leaking underneath your car – rather than water from the air-con system- is the smell of coolant.  

New concentrated coolant is a sweet fruity smell and can be quite strong, especially if you’ve recently had your car in for a tune-up. The smell can diminish in older coolant and if the system has been topped up with water.  In these situations, it may be more difficult to see whether the leak is coolant or, in fact, water from your air-con system.

Another telltale sign that the leak may not be from your air-con system is the color of the liquid. 

Condensation from your air-con system will always be water. This is what you want to see.

However, coolant comes in different colors. If you see a slight tinge of orange, pink,  red, or purple in the liquid underneath your car, this is a sign you have a coolant leak instead.

Does Aircon Cause A Puddle Under The Car In Winter?

The chances of having a puddle underneath your car in winter diminish because of the outside temperature. Because of this, it is wise to pay more attention to your coolant system to ensure that it is not what is causing the leak under your car.

Your car’s air con is part of the climate control system, and there are many benefits to having this active all year long. Because the air conditioning system takes the moisture out of the air, it will also help keep condensation out of the cabin in the winter. 

In Conclusion

You may be worried the radiator has burst and the car will probably overheat. The air conditioning system is considerably more likely to be the source of the leak, though. The air conditioner’s compressor works overtime in the heat which can lead to extra condensation and water.

What you are seeing is likely seeing in water from the air conditioning system. As mentioned, to be doubly sure, open that hood and look for a small black hose poking through the passenger side of the firewall by the windscreen.

With the air-con running, look for water coming out of the hose. If you see this, you have absolutely nothing to worry about. It is a natural process.

 If, however, with the air-con on, you see no water leaking from the hose, You have two issues to address

• If water isn’t leaking out of the hose, it is building up in the system and will eventually leak into the passenger part of the cabin.  It might have already, but you are unaware at this point. 
• It could be the coolant that is leaking underneath your car.  The obvious and easiest way to check for this, as mentioned, is the color and smell of the liquid.