Check for Puddles Under Your Car

Take a peek under your car. There are several fluids that could leak and cause problems for you. However, if you notice spots that could be water, it’s possible that you have condensation dripping as a result of a buildup of frost or ice. If this is the case with your car, you may also notice the AC temperature fluctuating back and forth between warm and cool. 

The underlying problem here is likely that your expansion valve is failing. This valve controls the amount of refrigerant that cycles into the evaporator. If not enough refrigerant is cycled, it can cause that part of the system to become too cold, which can lead to frost or ice on the outside of those parts. If too much is sent into the evaporator, it can cause what’s called a flooded evaporator. Both of those scenarios are likely to cause your car’s AC to run warm.

Check for A Refrigerant Leak

When you look under your car for drips, keep in mind they could also be refrigerant. One of the most common causes behind a car’s AC running warm is low refrigerant. This will happen naturally over time, which is why regular AC refresh services are recommended. If your refrigerant is leaking noticeably, however, it might be time to have the problem diagnosed by a technician. If you’re comfortable doing a bit of extra at-home maintenance, you can consult your owner’s manual to find the location and type of refrigerant in your car to top it off yourself. This should help your AC work properly if low refrigerant is what’s causing your car’s AC to run warm. Otherwise, you can make an appointment with a technician to have the problem diagnosed or to have an AC recharge.

Check Your Grille and Clear Any Excess Debris

Finally, and most simply, take a look at your car’s grille. As you drive, dirt and debris can build up on your grille, which will inhibit air flow. When not enough air flows through the grille of your car, it keeps refrigerant from properly cooling, which can result in warm air in the cabin of your car, even with the AC turned on. This blockage can also lead to more problems and necessary repairs, so it’s a good idea to keep an eye on the grille of your car, especially after longer road trips.

Lack of Regular Maintenance Can Cause Hidden Problems

Keeping up with a regular maintenance schedule is important for every system in a car, but especially so with the engine and transmission. A technician should be able to get an idea of how well taken care of a used car is by looking at the engine and transmission during a pre-purchase inspection.