Why your car air conditioner blows cold then warm then cold again

What are the likely causes of your car’s AC blowing cold and warm then cold again, and understanding how your car’s AC works and the solution for it?

Driving around in your car in scorching heat can be one of the most uncomfortable things to endure and can put you off completely from the thought of having to drive anywhere. This is why car air conditioners (AC) can be life savers when it comes to bearing heat while travelling.

So, what happens in the case where your car air conditioner may start to blow cold, then hot, then cold again? This inconsistency in delivering cool air when you need it most will not be ideal. Finding out the reasons as to why this might be happening will help as well as what to do.

What could be the possible causes of your car AC blowing cold then hot?

There could be a number of reasons as to why this could be happening. One of the causes of this could be that there is a leak in your cars air conditioning system. This will be a refrigerant leak which is why the air conditioner could be blowing warm air at times, due to the decreasing refrigerant that is leaking.

A leak in the car’s air conditioning system can likely be brought about by a moisture and refrigerant that has combined and produced a corrosive acid that is strong enough to corrode at seals, valves and hoses in the air conditioner’s system.

This refrigerant leak will likely be the cause of warmer air blowing out of the unit sometimes, as there is not enough refrigerant to produce cool air. Your air conditioner could have a malfunctioning compressor clutch.

This is considered as one of the most important components of your car’s air conditioning system. This is because it allows the pulley to engage and disengage from the power of the engine, so that the compressor is running only when it needs to be.

As it switches from on and off all the time, this can result in some wear and tear whenever you use your car air conditioner. The air conditioner will not blow cool air if the compressor clutch is not working properly.

Another possible reason for your car’s air conditioner blowing funny, could be an ineffective expansion valve. The expansion valve is possibly failing. The job of the valve is to eliminate pressure from liquid refrigerant to allow expansion from a liquid, to a vapour in the evaporator. A failing expansion valve could be blocked and restricting refrigerant flow.

A fuse that has blown or an electrical issue could also be another cause for your car’s air conditioner blowing cold and hot. Since the unit comprises lots of wiring, switches, relays and fuses that work together to help your air conditioner run, should one of them fail, your air conditioner could start blowing warmer air.

How does a car air conditioner actually work?

Knowing how a car’s air conditioning system works can help you understand what it means when your system starts to encounter problems. A car’s air conditioner works to eliminate heat and moisture from the air in the car, as opposed to generating cool air.

Cool air is generated from blowing air from outside the car or from the cabin over cold coils. This is what cools down the air prior to it getting blown out of the ventilation system into the car.

Most car air conditioner systems are set to blow very cold air that ranges from 32 and 40 degrees. The cooling coils is where cooling takes place, and the coils are cooled by cold refrigerant that flows through them.

Most cars make use of a R-134a refrigerant, which is specifically designed to work at temperatures and pressures needed in a car’s air conditioning system.

When the cold refrigerant passes through the evaporator, it will soak up the heat in the air, warming the refrigerant which then needs to be cooled down again so that the air conditioner can operate. This is possible through compression of the refrigerant to high pressure and also heats it up to high temperature.

The compressor then works to cool down the hot refrigerant. With the refrigerant now cooled, it makes its way to the evaporator to cool it meaning more cool air in the car.

What is a solution to a car’s AC blowing cold and hot?

When your air conditioner seems to be giving you trouble, the best solution would be to take your car in to aircon specialists and have them identify the problem.

Your car’s AC unit blowing cold and warm is not normal.

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