8 Common Air-Conditioning Problems Found By Home Inspectors

When you live in a hot climate like San Antonio or South Texas, air-conditioning is a big deal. I don’t think I’d live here without it! Air-conditioning was first invented in the 1920’s and involves the compression and evaporation of volatile gases called refrigerants in order to remove the heat from your home. While we’ve refined the process over the last 100 or so years, there are still quite a few moving parts to contemporary cooling systems nowadays and they aren’t plug-and-play; they do require maintenance.

The most common air-conditioning problems home inspectors find in San Antonio,TX:

Clogged Condensation Drains

Ever see water dripping out of the pipe in the sticking out of the ceiling of your porch or exterior wall above a window? That is probably your secondary condensation drain, and if water is coming out of that pipe, it probably means that your primary condensation drain is clogged! Cooling systems operate like big dehumidifiers, removing moisture from the air. This moisture has to go somewhere, so it collects on the evaporator coil and drains into a drip-pan, which is connected to a drain to the exterior. Periodically, this drain WILL get clogged, because the cool, damp and dark space inside the pipe is a prime spot for gunk and algae to grow. The primary drain line can periodically maintained by pouring dilute bleach or white vinegar down the condensate drain, such as when you change your air-filters, but eventually you will likely need to use compressed air to physically blow out the line. When you don’t, the line gets blocked and condensation then goes to the secondary condensation drain. Speaking of condensation drain…

The Absence of a Secondary or Safety Switch

Secondary condensation drains are not always installed unfortunately! These drains are technically optional, as long as another means of shutting down the cooling system is present should the primary condensation drain become clogged. But all too often, especially on older homes, do we see an air-conditioning system that does not have any type of secondary drain. An alternative to the secondary drain is a float switch installed in the primary condensation drain that will shut the system down if the primary drain becomes clogged and fills with water. We think of these devices as cheap protection against a potential flood should your condensate drain get clogged. A secondary or a safety switch is critical for homes with the a/c in the attic.

Condensation Drains Discharging Too Close to the Foundation

This condition won’t affect the performance of your cooling system, but it will affect the performance of your foundation and may just invite termites right to your doorstep. Condensate drains are required to discharge at least 36-inches away from a foundation. This should be easy to fix, you just need to extend the drain with PVC pipe or some other piping material. When you don’t do this, water may pool next to the foundation, which because of the common presence of elastic soils in San Antonio and Texas in general, can cause a wet spot where the soil in this particular area expands considerably more than the surrounding soil. This can create a high-spot in your foundation and contribute to cracking and other problems. Furthermore, having a wet-spot right next to your foundation is giving the subterranean termites a much easier time into your home. You’ve provided them with a water supply and plenty of moisture to import when they begin building mud tubes into your home.

Dirty Condensers

The condenser is the large noisy unit that exists outside. These systems contain a compressor that condenses the refrigerant and a large fan that blows air over the refrigerant lines to dissipate heat. These condensers are filled with aluminum radiator fins similar to a car’s radiator, and periodically these fins require cleaning. There are plenty of youtube tutorials about cleaning your own condensers as well as products that can be found affordably at your local hardware store, but you may consider contacting your local HVAC professional to provide a general cleaning and servicing of the system. Dirty condenser coils will reduce the lifespan of the equipment as well as reduce the energy efficiency of the equipment, so keep the coils clean!

No Insulation on Refrigerant Lines

The larger of the two refrigerant lines present for a cooling system is called the suction line, and this line will get very cold. It’s important to keep this line insulated with foam pipe insulation as condensation will form on the exterior of the pipe, which can then drip onto damageable surfaces (such as the drywall ceiling). We commonly find this insulation absent or deteriorated in attics, which can cause water damage to the drywall. Rats are also big fans of these lines and will commonly chew the insulation in order to drink the condensation that forms on the interior.

No Refrigerant Line Caps

Believe it or not, huffing air-conditioning refrigerant to get high is a thing, and because of this, special caps that can only be removed by a special tool are required to be installed on the refrigerant inlet ports of the exterior condenser units. These caps are pink, green or silver and are removed by a key that is only sold to licensed HVAC professionals. These caps are cheap, but the law requires that they be installed on all equipment serviced since 2012.

No P-Trap for the Condensation Drain

Depending on the orientation of the heating and cooling systems, a p-trap is commonly required by most manufacturers on the condensation drain. While most manufacturers recommend it on ALL installs, p-traps are particularly important when the evaporator coil / cooling system is installed upstream or before the heating system / fan, as these systems are now under “negative pressure”. When under negative pressure, air is being sucked out of the evaporator cabinet and the condensation drain, which without a p-trap, can adversely affect the performance of the condensation drain. These are easy to install, but small details like this are important to the performance of your cooling system.

Inadequate Cooling Performance / Poor Temperature Differentials (Delta-T)

Probably the most concerning of the problems on this list are poor temperature differentials. If your San Antonio home inspector is any good, they will insert a probe thermometer into the air handler near the evaporator coil and stick a probe thermometer near the return air vent, let the system operate for 20 to 30 minutes, and then compare the measurements. If the temperature differentials (commonly called Delta-T) are between 15 and 20 degrees, the system is performing adequately. If the Delta-T is outside of that range, the system may not be performing adequately and may need further evaluation. Common conditions that could affect the delta-T reading include very high humidity, dirty air-filters, inadequate return air, and more. If your home inspector produces a comment that states inadequate cooling performance, definitely reach out to your local HVAC professional to get things checked out.