Why Your Home Air Conditioner is Not Cooling Your Home

Nothing can ruin a nice day faster, than feeling warm air blowing out of your homes central air conditioner system, or discovering that the air conditioner just won’t cool your home no matter how much it runs! Aside from the discomfort that comes along with heat and humidity, there’s the sinking feeling inside your stomach that you have to call out the HVAC repair company, and be faced with a high central ac repair cost, or worse… having to replace the central air conditioner completely!

In this DIY Reviews Guide, we’ll walk through several of the reasons why your air conditioner is not cooling your home. Although we’ll try to provide a few tips on what you can check, it’s always best to call in a professional to have a look at it as well.

Reasons Your Central AC Blows Hot Air, or Just Won’t Not Cool Off Your House

1 – Not Turned On at Thermostat!

Many thermostats have a separate setting for heating and cooling. Take a look at the thermostat and make sure that the set point is lower than your inside temperature, and that the function switch is set to “cooling” or “air conditioning”.

2 – Doors or Windows Left Open or Poorly Insulated

Remember how your father always used to ask… “Do you live in a barn” and tell you to close the door to the house? Well, its very true today as well. When the central air conditioner is running, you should close all doors and windows tightly to seal out ANY warm air from outside. Also check the doors and windows for tight sealing, so the cool air doesn’t leak out!

3 – Dirty Return Air Filters

Your central air condition MUST have a free-flowing supply of fresh air in order to transfer the heat from your home. Imagine how long your car would run if you put a piece of cardboard in front of the radiator… right, not long at all! Open the return air grill that holds the disposable filter (there may be more than one, check them all) and take a look at the filter. If its more than 45 days old, replace it. If it’s plugged completely, remove it and let the unit run for 30-45 minutes, then replace it with a new filter.

4 – No Return Air Filter in Place

If you are one of those crafty people who had the idea of removing the return air filter and leaving it out for more than a few hours at most, you may have allowed all that dust and buildup to accumulate on your evaporator coil. Without a filter in place, all the dust plugs the coil and no air can get through it. Call out a repair company to clean the coil. (get free quotes)

5 – Low Refrigerant Pressure (Freon)

Central air conditioners use pressurized refrigerant to remove the heat from the air in your home. When it gets low, the thermal properties change and it doesn’t get to a cold enough temperature to effectively cool the air. In order to check the level of refrigerant, a trained (and EPA licensed) technician needs to connect a set of manifold gauges to your outdoor ac condensing unit and check the pressures.

The cost to replace the refrigerant depends on many factors like the type of freon used in your system, whether there is a leak or not, and how much is used. Typically, the cost to recharge a central ac unit will range between $150-$400 and could go much higher if you need leak detection or part replacement.

6 – No Refrigerant (Freon) at All!

No refrigerant usually means there is a major leak or breakage in the cooling circuit. Since the freon lines are permanently sealed when they are installed, they should never leak out. If your system is more than 10 years old and it’s freon has leaked out, you can expect a significant repair cost to not only locate the leak, but to repair it. In many cases, unless it was a known mishap that caused the freon to leak out, you may be faced with replacement due to the age of the system.

7 – Central Air Conditioner was Stolen!

The price of copper is high and thieves are well aware that a central ac unit filled with copper tubing is worth money at the local scrap yards. Newer systems are using aluminum versus copper but even that has a scrap value.

If you outdoor ac condensing unit was stolen, you should first call your insurance company and file a claim. They are usually covered by homeowners insurance. Next, have a company come out and provide replacement estimates for the entire system, so you can be sure nothing else is damaged.

8 – Central AC is Too Small for the Home

Having an improperly sized central air conditioner is not only going to effect how poorly the unit cools your house, it’s going to cost you a lot of money due to running inefficiently! The only way to be sure you have the right size central ac unit is by performing a detailed load calculation completely on the home.

A load calculation will take into account several factors other than just the size of the rooms. things like the direction of the afternoon sun, attic insulation, window r value, and many other technical factors go into making sue you have the right size.

9 – Poorly Insulated Duct System

After the cool air leaves your central air handler, it travels through a duct system and then out the vents to the spaces of your home. If the insulation on or around the duct-work in your home has lost its value, the air will just warm up along the way to the rooms.

An easy way to check if it’s the duct system is by measuring the temperature of the air as it leaves the air handler, then again at the vent where it blows into the room. Large (+5 degree change) temp changes should prompt a call to a pro to check the duct insulation.

10 – Leaking Duct System

Just like a poorly insulated duct system having a negative effect on your home cooling, leaking duct is even worse! not only does it allow warm air to be drawn into the system, it may lead to a dangerous black mold buildup! Your ducts should be checked at least one a year during normal HVAC maintenance to be sure it’s tightly sealed and working properly.