What might be causing your AC to blow warm air?
We are thinking you are the type of person who looks for good news first. The good news is part of the system is working or it would be blowing air at all. Specifically the indoor part of the unit is working. The outdoor part has an issue, or the thermostat has an issue. Here is what it could be.
The thermostat settings
Issues here are a score from a repair standpoint. Maybe your children have been playing around with the thermostat after a Saturday afternoon viewing of Frozen. Or perhaps your spouse has been trying to recreate the hot yoga classes that are all the rage, though you can’t deny that he does look good in yoga pants. Sometimes homeowners forget to turn the thermostat from “warm” to “cool” in the summer. Also make sure that the temperature is not set too low. No your unit will not really get your home down to 50 degree just like my Toyota Rav4 will not really get up to 130 MPH, I didn’t check but I’m guessing. Setting it too low sets you up for other issues like freezing up the condenser coil.
We recommend making a note to yourself before summer comes to turn it on “cool” mode and stick it to the fridge or in your calendar for the first day of summer.
How to fix it: Check your thermostat and see what mode it says it’s in. Also check the temperature and adjust it accordingly.
Maybe it is the air filters
Hope so, it’s the best case scenario. When is the last time you changed or cleaned the air filter in your AC? Most people never do until something goes wrong. Air filters do get dirty and this blockage won’t clear up until you or a technician takes it out and replaces it. The filter alone will not cause warm air to blow, but it will contribute to the problem and reduce cooling effectiveness significantly.
Causes and how to prevent it from happening: Air filters are there to catch dirt and debris that may be flowing through your internal unit. If they are doing their job, they become dirty and need to be cleaned or replaced. You should check on it regularly. Some systems just have a filter in the return grill and some systems have large media filters that sit in the air handler or furnace under the house or in the attic.
How to fix it: Turn the unit off, order a new filter or clean it, then reinstall it back to its original position.
Refrigerant Leak
File this one under medium bad.
Refrigerant leaks are very common cause of a system blowing warm air. They can be caused by a faulty installation, vibrations causing the leak, there are many joints and connections that can weaken over time. Additionally, copper is subject to corrosion caused by pollutants in the air such as hair spray, cleaners, air fresheners and “off gassing” by building materials and furnishings. This type of corrosion attacks the copper tube walls of the indoor coil and causes leakage usually in more than one location. This creates a Swiss Cheese Effect but not the delicious kind. This type of leak can be repaired but it is many times wiser and less costly to replace the entire coil for the best reliability. Age is also a factor in susceptibility to leakage, and as the refrigerant circulates under high pressure, there is wear on the inside of the tubing which over time will cause a thinning of the tube walls. As units have become more efficient leaks have become more common because the walls of the evaporator coil are being made thinner.
Gas and GO
In industry parlance this is charging up the system with refrigerant which will usually restore cooling for some period of time but will eventually all leak out again, may take a day, may take a year. If this continues for several recharges, the oil in the compressor will deplete enough to damage the compressor and require a major and expensive repair. Aside from being costly, a leaking system adds refrigerant to the atmosphere and isn’t particularly good for the environment.
Repairing the leak is the only option that makes sense. Yes the cost to repair is higher than simply recharging the equipment but once the repair is made, the reoccurring costs of recharging because of that leak are eliminated.
Where is that leak?
Finding the refrigerant leak is the key to making the repair. Sometimes the leak is at a joint and is easily repairable, sometimes the leak is in the lineset somewhere behind a wall in your home, and sometimes the leak is in the evaporator coil. Evaporator coil repairs are major repairs that require a cost benefit analysis to see whether the repair or system replacement is most appropriate. Repairing a single leak from a leaking fitting might be only a minor inconvenience and expense.
Recharging with refrigerant.
• Type of refrigerant your system needs— Older ACs need to use R-22 refrigerant. It’s expensive and rising because it’s being phased out. This means there’s less supply for something that’s still in high demand, so cost goes up. Newer air conditioning systems use the more environmentally friendly R-410A refrigerant.
• Time of the year— Prices go up in summer because demand is higher.
• Local climate—Places with warmer climates, like Durham and Chapel Hill North Carolina, have higher demand for Freon, so the price is higher.
How to fix it: Refrigerants are dangerous and should always be left to a professional. Handling refrigerant is something that requires a Environmental Protection Agency certification
Frozen AC Unit
No way, thats impossible on a 100 degree day.
Weird but true. Air conditioners and heat pumps can actually freeze into solid blocks of ice. This is one of the most common calls we get during the summer. The frozen part is the evaporator coil, which can block the cool air flowing into your home. Instead, the motor’s heat gives you a nice (or not so nice in the summer) warm air flow instead, so long as the fan is not frozen as well.
Causes and how to prevent it from happening again: Inside of the unit, condensation can occur on the coils and is intended to evaporate. This creates cooling just like when you sweat. But if the coiling power is reduced say by blocked air filters or low refrigerant pressure then it doesn’t. This condensation can build up and freeze if the temperatures at which the AC is trying to blow falls below 32ºF. Typically this happens on a hot day when homeowners turn their AC on the lowest setting. To prevent this from happening, you should keep your thermostat on auto around 70 or 72ºF or higher and keep an eye on the unit, inside and out.
How to fix it: First, turn it off and let it thaw. After about an 2 or 3 hours, it should be safe to turn it on, but it may still freeze back up. You have an issue, let us come take a look.
Blown or Tripped Breaker Switch
Both the indoor and the outdoor units have breakers that flip when there is a power overload of some kind. When too much current is flowing the breaker switches off as a safety precaution. Sometimes when the compressor or fan motor are starting to struggle they pull more power to start up than the system is designed to handle and that flips the breaker.
How to fix it: To “fix” the problem or rather just the symptom of the problem, simply flip the breaker back to the “on” position. If that does not fix it, contact a repairman. One hack that we have seen a lot is for the breaker to be switched out with a large one. Usually this is a temporary solution at best and potentially unsafe.
Bad Compressor = Bad Heart
This isn’t the best news. What a compressor does is to take the refrigerant from the evaporator and raise the pressure and the temperature. Which creates the flow to the condenser. It’s the heart, the refrigerant is the blood.
When the compressor fails the whole system ceases to function.
Causes and how to prevent it from happening: The compressor could go bad for a variety of reasons, but most common to blame is:
• Electrical failures
• Refrigerant not coming back to the compressor
• Overheating
How to fix it: Replace the compressor or the outside unit
Wiring
If the refrigerant is the blood of the system the wires are the nerves. Many types of wires and electrical connections existing in your heating and cooling system. It only takes one wire that has frayed or come loose or burned out to shut you down.
Causes: Ants, vibrations, water, lightning.
Solutions: the system electrical systems and components need to be checked out with a meter to pinpoint where the problem lies.
There are many potential reason that your system may be blowing hot air. Most unfortunately do require a repair of some type. But with at the least we hope we have given some insight into the potential causes and likely necessary remedy.