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6 Reasons Your A/C Is Blowing Hot Air

These are the most common reasons your A/C is blowing hot air: a refrigerant leak, broken parts, and electrical problems. Some of these can be quick fixes.
6 Reasons Your A/C Is Blowing Hot Air
6 Reasons Your A/C Is Blowing Hot Air

It’s one of those summer days in Virginia. The weather’s so blazing hot you can barely drag yourself from your air-conditioned house out to the car. And then, like a cruel joke, the A/C pushes warm, stale air into your vehicle. Nothing can spoil warm weather fun quite like a broken car air conditioner. The A/C is one of the most complex systems in your vehicle. You may need an experienced vehicle A/C repair shop. If your A/C is blowing hot air, there could be several causes.  We’ll explain a few of the most common ones.

Most Common Reasons Your A/C Is Blowing Hot Air

1. Refrigerant Leak

A car A/C blowing hot air is often the result of a refrigerant leak. Refrigerant is a fluid that circulates through your car’s A/C system, expanding and contracting as it removes heat and humidity from the cabin. None of the other A/C components will function correctly without proper refrigerant levels.

A leak can happen because of an old hose as well as a rusted or punctured evaporator. But don’t expect to easily spot a refrigerant leak. You probably won’t notice a puddle of liquid in or under your car. That’s because unlike motor oil and other vital car fluids, refrigerant evaporates when exposed to the atmosphere. Sometimes, you’ll get lucky and notice an oily residue at the exact location of the leak.

To definitively identify a refrigerant leak, one of our expert technicians needs to inject dye into the system to trace it. Once they identify the source of the leak, they repair and recharge your car A/C so it can blow fresh, cold air once again.

2. Worn Out/Broken Compressor

The compressor is the heart of your car’s A/C. It’s responsible for circulating the refrigerant through the system. If this part isn’t working correctly, the refrigerant won’t be able to reach the condenser for cooling. A failing compressor can also cause your engine to overheat.

Compressor issues tend to pop up after long periods of inactivity, such as long winters when A/C isn’t necessary. (To prevent this from happening, many newer vehicles keep the compressor active year-round by activating it under the defrost setting).

To keep your compressor in good shape, turn on the air conditioner on the highest setting once every month, even during our cold Virginia winters. If your compressor has already failed, though, contact our shop for a repair.

3. Problems With The Electrical System

Person turning air conditioning knob while A/C blows hot air

If all the A/C components are in working order, your car A/C may be blowing hot air because of an electrical issue. Your vehicle’s A/C is electrically powered; if any one of the components in its arrangement of fuses, relays, and switches stops working as it should, the entire electrical system will shut down.

Your car’s electrical system is a complex net of wires that can be difficult to pick apart for the untrained eye. Diagnosing and correcting an electrical problem begins with performing a thorough visual inspection of your car’s fuse box and wiring.

4. Broken/Faulty Condenser

When your A/C system pulls the heat and humidity out of your cabin, the refrigerant absorbs them. In turn, the condenser’s function is to keep the refrigerant cool so the cycle can continue. If the condenser isn’t doing its job, the process breaks down. That’s when you get slapped in the face by a blast of hot air.

The condenser is at the front of the car, between the radiator and the grille. It utilizes air flowing through the grate or grille to assist in cooling. If the condenser is blocked or clogged by road debris, air won’t reach it, preventing the refrigerant from cooling correctly.

If you have a faulty condenser, you may be able to see the problem by looking through the grate. Also, consider whether your car A/C problems started after a fender bender or bumper bump, in which case your condenser might have broken or been punctured on impact.

Check your grill and remove any sticks, small rocks, etc. This simple DIY action might stop the problem of your A/C blowing hot air.

If not, bring your car to our shop. The A/C system may need flushing or mechanical repair.

5. Hot Air Blowing through a Stuck Blend Door

Starting your car forces warm air to flow over your engine and into your car; this is something that the blend door (aka “air mix door”) helps to fight against. When the blend door flips over your ventilation system, it stops this warm air from entering the cabin and allows your A/C to pump in the cool air you need. If your blend door is stuck, no amount of cool air will ever get through; you’ll just get warmer and warmer.

6. Broken Cooling Fans

A pair of cooling fans form an important part of your car’s A/C system. Their purpose is to help remove heat from the refrigerant fluid. If either of them becomes cracked or otherwise damaged — usually due to flying road debris — the refrigerant will not be adequately cooled, and you’ll find your A/C blowing hot air. It’s also important to check to make sure they are running at the corrected speed – make sure nothing is jammed between the blades, like leaves or bugs.

A broken cooling fan will need to be replaced by a reliable auto shop that does A/C work.

How To Fix Your A/C From Blowing Hot Air

So if you’re feeling a bit sweaty in the front seat, take a look at the list above or stop by to see one of our professionals at Mission Auto Repair in Winchester, VA so we can take an in-depth look at your car’s A/C system for you.

“Customer service was great. We dropped our truck off at closing Thursday hoping the a/c would be fixed by Friday afternoon because we were going out of town. Sure enough everything was done by 3 on Friday. We were very grateful.”  – Kim W.