• Have you ever turned on your air conditioning unit on a scorching hot day only to find that instead of providing much needed cooling relief your home actually ends up getting hotter? It's a complete drag, isn't it? Actually that's a huge understatement—having your air conditioner blow hot air is an absolute disaster.

     This is actually a fairly common problem, and although there are a number of different causes they all have fairly straightforward fixes. So that's what we want to do in this article; we want to show you how to identify the cause of a faulty warm air blowing air conditioning unit and then fix this problem.

     Here are some of the most common causes of this problem:

    1. The thermostat's fan is on the wrong setting.
    2. The AC unit is leaking refrigerant
    3. The air filter is dirty and clogged up
    4. The outside unit is dirty
    5. A breaker's been tripped
    6. Drain line is clogged

     When it comes to an air conditioning unit blowing hot air these are the six usual suspects. Let's go through each of them one by one.

     1) The Wrong Thermostat Fan Setting

    Your thermostat controls a fan in the air handler section of the unit. (An air handler is a metal box that aside from the fan also houses an evaporator coil and controls). If the fan setting is set to 'On' this is most likely the problem; this means that the fan is running around the clock, even when the air isn't being cooled by the outdoor unit. To solve this problem, change the fan setting to 'Auto'. On this setting the fan will automatically turn on only when the outdoor air conditioner is also on, ensuring that you only get cool air.

     2) Leaking Refrigerant 

    Refrigerant is a liquid that absorbs ambient heat from the air and traps it. If your unit is running low on refrigerant then, the air that it blows will not be adequately cooled, and the only way that an AC unit can be running low on refrigerant is if there's a leak. All AC units should have a stable amount of refrigerant; this particular liquid does not get used up like gas.

     Here are the tell-tale signs of a refrigerant leak:

     -The refrigerant line has frozen

     -You can hear a distinctive 'bubbling' or 'hissing' sound (if you can hear this sound than this means that the leak is quite extensive)

     -The unit is not cooling during the day but does at night.

     Handling refrigerant is tricky business and potentially very toxic so there is no simple DIY solution for this particular problem. If you have found this problem you need to hire a professional air conditioning repair company to find the exact spot where the leak is, fix it, and replace the missing refrigerant.

    3) A Dirty Clogged Up Air Filter

     If you let your AC's air filter go without being replaced or cleaned for too long it gets filled with dirt this not only stops this one particular component from working properly, but it can actually cause serious damage to the rest of the unit. You need to replace the air filter so the air can flow back into the air handler section of the unit where it can be cooled.

    Checking the air filter is easy to do, and should be done at least once a month. If there's any dirt in there, it should be cleaned out immediately.

     4) A Dirty Outside Unit

     The outside unit that's part of your air conditioning system has one main purpose: to release the heat absorbed by the refrigerant so the refrigerant can then absorb and trap more heat. If this sounds confusing, it would be wise to read up on how air conditioning works.

     At any rate, if the outside unit becomes too dirty and it can't disperse this heat than the entire system struggle to cool air adequately due to overheating. You should therefor make sure to clean the outside unit at least once a year. This is easy to do with a garden hose, but you want to make sure to go lightly. The outside unit contains fragile condenser coils that are easily bent and damaged by the heavy water pressure of a garden hose cranked all the way up.

     5) A Tripped Breaker

     An air conditioning unit has two separate breakers (one for the inside unit and another for the outside). If the breaker for the outside unit gets tripped this will mean the air is not being cooled due to the compressor in the outdoor AC unit not pumping refrigerant to the indoor evaporator coil. Thus, your inside unit will still blow air, but it won't be air that's been cooled.

    So check your breaker box, and if a breaker's been tripped reset it. However -and this is very important- if after resetting the breaker it immediately trips again don't just simply reset it. If this is happening it's time to call a professional.

     6) A Clogged Drain Line

     When running air conditioning the system always produces condensation that must be removed from the air handler (indoor unit) and drained outside, normally through a 3/4' PVC drain line. If this primary drain line becomes clogged there is a float switch attached the drain pan underneath the unit or installed directly in the drain to turn the outdoor air conditioning unit off to prevent water damage to the property. If you find this pan full of water or the float switch tripped you must remove the water from the pan underneath the unit with a wet dry vac or other means to restore operation.

     Now that you have removed the water and the system has began to cool again you are not out of the woods yet. There should never be water in the secondary pan unless the primary drain is clogged, now you have to clear the drain with the wet dry vac or compressed air from outside the structure where the PVC drain comes out (usually by the outdoor unit). If clearing from outside make sure there is no vents in the drain and if so cover with tape before to ensure you are pulling or pushing through entire drain (The drain can also be cleared from the attic if accessible through a cleanout port or if the PVC fittings are not glued).

     There may be other reasons to call an air conditioning professional. We have covered 6 very common problems, but there are others. At any rate, owning an air conditioning system is like owning a car, and although there are a few issues that the owner can address fairly easily, regular scheduled maintenance with a pro is always a good idea.