4-Step Guide To Troubleshooting A Central AC Unit That Is Blowing Warm Air

If your central air conditioning unit is no longer blowing cool air, you may wonder if there is anything you can do to find and fix the problem yourself. If so, use the following four-step guide to troubleshooting your central AC unit that has started to blow warm air.

Step 1:  Examine the Filter

One possible explanation for your air conditioner not blowing cold air is that the air flow through the unit is blocked. If the air is not able to circulate freely through the system, the cold air will never make it to your home.

In this first step, examine the air conditioner's filter to see if dirt has clogged up the holes. If so, change the filter, then see if this makes any difference. If not, go on to the next step.

Step 2:  Check the Vent Fins for Clogs

If changing the filter had no effect on the temperature of the air, check the external vent fins for clogs or blockages. If these external vents have become blocked by bushes or clogged up with mud, the air conditioner is unable to suck in the required air to push the cold air through your ductwork.

If plants grown over the vents, trim them back so there are several inches of air space around the unit. Then, use a brush to clean off any excess dirt on the vents.

Once you brushed away the dirt, wipe the vents with warm water containing a teaspoon of dish detergent. If cleaning the vents has had no affect on your home's temperature, go on to the third step.

Step 3:  Make Sure the Blower Is Working

When the vents are cleaned out but your air conditioning unit is still not cooling your home, another possible problem could lie with the unit's blower. If the blower's motor is no longer operating properly, the air conditioner will not be able to pull air in through the vents or push air out through the compressor.

To check the blower, turn your thermostat down as low as it will go, then stand next to the air conditioner. After a few minutes, you should hear the blower kick on. You may hear a click or a gentle thud.

However, if the blower does not kick on, this is probably the problem with your air temperature. Or, if the blower turns on but you hear whining or smell an odor like burnt wire, the motor may be getting ready to die. Either way, you should have a professional inspect it as soon as possible.

If the blower seems to be working properly, go on to the next step.

Step 4:  Inspect the Compressor for Ice

Another potential cause of warm air coming out of your AC unit is that ice has formed over the air compressor. This ice could form due to a couple of reasons.

One reason your compressor may have iced over is a combination of the problems discussed in the first two steps. If the air cannot flow freely, it will sit inside the unit and freeze any condensation inside.

Turn the unit off for a few hours to let the ice melt, then turn it back on after the ice has melted. If it freezes again, there could be another issue at play.

Another reason for the ice is leaking or low coolant. If the coolant is leaking onto the compressor, it will freeze instantly. And, if the coolant is low, it will not feed the unit evenly, causing short spurts of extra-cold fluid running through the compressor. Either of these problems should be handled by a trained HVAC professional.

If you found an issue during the last two steps, you need to have an experienced HVAC contractor inspect the unit. After finding the problem, they can discuss with you options for repairing your air conditioner, as well as talk about setting up an AC maintenance schedule to help avoid problems in the future.