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AC Condenser Pads: Everything You Need to Know About Protecting Your Outdoor Air Conditioning Unit

If your air conditioning system is any larger than a simple ductless window unit, there’s a pretty good chance that you’re going to have at least part of the system outside your home. Both the indoor and the outdoor units play a vital role in cooling the air and keeping it flowing through your house, so it’s important to protect both units from damage. Protecting the indoor unit is relatively easy since it’s inside your house, but the outside unit is more vulnerable, especially if you live somewhere with harsh weather during the winter. Failing to consider the protection of your outdoor unit can create some real problems for you down the road, so it’s better to think about it when you’re first installing the system.


Luckily, there are plenty of things you can do to keep your outdoor AC unit safe and secure for years to come. This includes steps you can take during installation, like adding a condenser pad, as well as things you can do throughout the lifetime of your air conditioning system. With proper care, protection, and maintenance, you can keep your air conditioning running for years without any major problems, saving you the hassle of having to repair or replace any parts of the system.


How a Split-System Air Conditioner Works

Split-system air conditioners are the most commonly used household HVAC systems. They work more or less the same way as smaller window AC units, but the components are split into two different units. This allows each part of the system more room, making the system itself more powerful as the size of the components is scaled up. The biggest difference between a split-system air conditioner and a ductless window unit is therefore the capacity and power of the AC system. Split-system air conditioners also tend to use ducts to push air all throughout the house instead of just blowing cool air out the front of the unit, allowing you to cool your whole house with just a single AC unit.

Ductless Split Systems


The way these systems work might sound complicated, but it’s pretty simple if you break it down. There are only a few components that you really need to know to understand how air conditioning works: the compressor, the evaporator coils, and the blower. There are some other parts, of course, but these are the most important ones.


The outside unit holds the compressor and is responsible for handling the system’s refrigerants, the chemicals that the whole system runs on. Refrigerants start inside the outside unit in a gaseous state before the compressor forces them into a liquid state. Going from a gas to a liquid creates heat, which is expelled through the back of the outdoor unit – that’s why there’s always hot air blowing from your AC unit. The now-liquid refrigerants are forced through the condenser coils and passed into the inside unit, which houses the evaporator coils. The evaporator coils are essentially the opposite of the compressor. They reduce the pressure on the refrigerants, allowing them to return to a gaseous state. This process creates a heat transfer, cooling the surface of the evaporator coils. The refrigerants are then passed back to the outside unit to start the whole process over again.


This is where the air comes in. The inside unit has a blower that sucks warm air in from your house and passes it over the evaporator coils, which have been made cold to the touch by the heat transfer from the refrigerants. This cools the air. The cool air then stays inside the inside unit until the thermostat detects that the house is too warm and the unit blows the cold air back into your home.


As you might imagine, the compressor and condenser coils are a vital part of this process. Without these parts, the evaporator coils can’t cool the air, and the entire system is useless. That’s why it’s important to keep the outdoor unit from being damaged.


AC Condenser Pads

One of the first things you should install when you’re setting up your AC system is a condenser pad. This is the single most important thing you can do to protect your unit and should be on the top of your list when installing the system. Because of the chemical reactions going on inside the outside unit of your air conditioner, it’s not a good idea to just leave them sitting on the ground.

What is HVAC

This is true for a few reasons. First, an AC unit sitting flat on the ground is exposed to a number of potential risks, including rainwater pooling on the ground or even just corrosion from the soil underneath. Raising the unit helps protect it from these issues. Second, because the compressor and condenser coils hold refrigerants in a liquid state, it’s important that the unit be kept still and level while it’s on. Even if the ground under the unit is relatively flat, the weight can cause the soil underneath to shift, leaving the unit unbalanced and causing problems for the system.


The way to avoid these problems is by installing a condenser pad when you’re first installing the unit. The pad is just a flat rectangular slab, usually made of concrete, that the unit is then placed on top of. This keeps the unit elevated and safe from pests and water damage while also making sure it stays flat and level. As long as the pad has been made and installed correctly, this is a one-time cost for the homeowner. Even if you later upgrade to a different AC system, you can still just use the same pad as long as it’s big enough to hold the unit. It might be tempting to skip the pad after you’ve just dropped a hefty chunk of change on a new air conditioner, but installing it correctly can save you a ton of headaches in the future. Here are a few things to keep in mind when choosing the right condenser pad for your property.


AC Condenser Pad Size

Choosing the right size for your condenser pad is important, and is mostly based on the size of your unit. However, you should also consider the elevation from the ground when making your decision. Typically, a condenser pad should be at least three inches off the ground, but you might want to make it a little taller if you live somewhere that gets a lot of rain. If you’re worried about the weather or your property has drainage issues, you may want to just bump that up to as high as six inches.


As for size, you obviously need to make sure the pad is big enough to fit the unit with plenty of space around. Keep in mind that you may want to re-use the same pad if you get a bigger unit, so leaving a little extra room to grow is a good idea as well. It’s worth noting that an especially heavy pad might shift or sink into the ground if the soil is loose, so make sure you have a conversation with your HVAC contractor to figure out the best size and location for your property.


Pad Material

While condenser pads have traditionally been made of concrete, you now have a few different options for materials. If you have a large or heavy unit, you should probably just stick with concrete. While it’s not necessarily the most aesthetically pleasing material, concrete is more than strong enough to hold even the heaviest AC units. Besides the look, the biggest downside of a concrete pad is the extra cost of bringing someone in to set the actual concrete for you. It might cost a little more upfront to stick with concrete, but the pad will most likely last for decades without any issues.


These days, you can also purchase your own condenser pads made of recycled plastic or rubber composite. Composite pads are easier to move and install, and will still last just as long as concrete if they’re installed correctly. However, heavier AC units can have too much weight for composite pads to handle, which means you’ll have to get a new one anyway when the old one inevitably collapses. As a general rule, if you have a larger unit, you should stick with concrete. If the unit is smaller, composite pads are a more flexible option since you can potentially move them around when you install new units.


AC Condenser Pad Location


HVAC system

Generally, outside AC units are placed around the back or to the side of a house, to minimize the noise factor. Once you’ve chosen the right location for your unit, you’ll have to make sure it’s ready for the pad. Before you install the condenser pad, you’ll first have to level the ground underneath. This is especially important for composite pads, which are lightweight and sit on top of the ground. Once the system has been installed, if you notice the ground shifting or if the unit seems unbalanced, don’t try to fix it by yourself. AC units are extremely heavy, as are the concrete pads underneath. To avoid hurting yourself, bring in professional help to evaluate the situation and fix it.


Vibration Pads

A well-placed condenser pad will protect your AC unit from most things, but there’s still one more piece you can add to be extra sure. Because of the large fans and motors inside an AC unit, they have a tendency to shake and vibrate when they’re running. This is totally normal, but it can cause problems long-term as the metal case of the unit rubs against the ground or the concrete of the condenser pad. It also makes a lot of noise, which can be disruptive for the people inside. To avoid damaging the air conditioner, you can add a vibration pad under each of the four corners of the unit. This will prevent the case from grinding on the concrete as well as muffling the noise of the vibration. If you choose to install vibration pads under the unit, take care to keep it level. If the pads are uneven, then the whole air conditioner will tilt slightly. You should also check periodically to make sure the pads haven’t shifted, just once every couple months or so.


Weatherproofing Your Outdoor AC Unit

Central AC Installation

While outdoor condenser units are generally built to be tough enough to survive harsh conditions, there are still some things you can do to make that a little easier. The condenser pad will go a long way towards protecting the unit from potential hazards on the ground like corrosion or insects, but weather can still cause some damage, especially over a period of years. Here are a few things to keep in mind when you’re installing and maintaining an outdoor AC unit:


Allow For Shade

Generally, everybody wants to install an outdoor unit somewhere tucked away at the back of the house where it can’t be seen. However, when deciding where to place the air conditioner, you should start by looking for the areas with the most shade. Radiation from the sun can damage even the toughest machines over a long enough period, so keeping the unit in the shade is a good way to potentially extend its lifespan. Perhaps more importantly, a shady spot for your AC can save you a little extra cash on your monthly electricity bill. Sitting in direct sunlight will cause the unit to warm, which means it has to work harder to cool the refrigerant in the condenser and the compressor coil. It might not be much, but you’ll definitely notice a difference if you keep the conditioner out of the sun.


Another thing to keep in mind when installing the unit is whether or not there’s enough space around it. While it’s tempting to tuck the condenser away in a little corner, an enclosed space can make maintaining the unit significantly more difficult. Make sure to leave enough room for an HVAC technician to get in and disassemble the unit if necessary. The condenser itself also needs a little room to breathe. If the unit is expelling hot air directly into a wall or other obstruction, the air will only come back and hit the condenser itself, warming it. You need to ensure that the warm air has enough room to dissipate.


Keep Your Plants Trimmed

Using plants or shrubs to hide the AC unit is a great way to keep your yard looking nice. However, you should be careful not to let those plants grow wild. Leaves, branches, or vines that grow on or even inside the unit can damage it or even tangle up the fan motor. While plants can be a great way to provide shade for the air conditioner while helping it blend into your lawn, you’ll need to stay on top of maintenance to keep them from causing problems inside the condenser unit. One good way to keep a distance between the plants and the AC unit is to lay down some gravel outside the perimeter of the condenser pad. This also prevents grass and weeds from springing up too close to the unit.


When you’re doing the actual trimming, keep an eye on where the cuttings go. If any debris gets inside the unit, it can get tangled up in the fan or even contribute to sludge in the motor. If you can, try to position yourself between the plant and the air conditioner, just in case. This also applies when you’re mowing the lawn. Avoid letting the mower throw mud, dirt, and lawn trimmings into the unit. You should also take extra care to avoid driving the mower over any rocks in the grass. Not only can the rock break a window or hurt somebody, but it could dent or damage the AC unit as well. Your best bet is probably to just put something between you and the unit when mowing the lawn, even just a tarp or plastic sheet that can catch errant grass trimmings.


Covering the AC Unit for Winter

hide the air conditioner outside

As the weather gets cold and you stop needing to use your air conditioning, it’s generally recommended to cover the condenser unit to keep it safe from snow and debris until the spring. Not only will this extend the life of the system by protecting it from inclement weather, but it also makes cleaning it significantly easier when the warm months come along. Keep in mind, however, that covering the unit the wrong way can actually damage it, so it’s important to make sure you’re handling it correctly.


One common mistake is to cover the condenser with a weatherproof tarp. While that will keep debris, snow, and rain out, it also keeps moisture in. Under the tarp, moisture from condensation will be trapped inside the unit, gathering on the coils, screws, and electrical wiring. This allows rust to form, and greatly increases the chances of these essential parts failing. Instead of a tarp, find a proper air conditioning cover from a har

dware store. These covers are often custom-fitted, and are made of weatherproof vinyl or plastic. Unlike a tarp, however, they also have strategically placed vents that allow air and moisture to escape, preventing rust from forming inside the air conditioner.


If you’re looking for a quicker solution, here’s something HVAC professionals have been doing for years to cheaply and easily protect their own condenser units. Just cut a piece of plywood, place it on top of the unit, and hold it down with a couple of bricks. It’s quick, easy, and allows air to flow through the condenser while protecting it from falling debris. We recommend that you use marine grade plywood if you have it, for that extra protection from rain and snow. Whether you’re using the plywood or a fitted AC cover, having something protecting the unit during the winter is highly recommended if you want to extend its lifetime and avoid maintenance down the road.


Maintaining Your AC Condenser Unit

It might not be as fun as setting concrete or buying a fancy AC cover, but regular cleaning and maintenance is vital if you want to keep your air conditioning system running for years to come. As a general rule, it’s recommended that you give both parts of a split-system air conditioner a good cleaning twice a year – once in the spring before you turn it on for the first time, and once in the fall before turning it off. Here are a few things you should make sure to do every time you open up the AC unit:.

  • Check the filter – The inside air conditioning unit has a filter that purifies the air it pulls in before blowing it across the evaporator coil. If this filter gets too dirty, it can reduce the efficiency of the system, causing it to use more electricity. It’s actually recommended that you check the filters once a month during the cooling season, or twice a month if you have pets that shed. How often you have to replace the filter will depend on which kind you purchase, so pay attention to the packaging whenever you buy a new one.
  • Clean the coils – Both the evaporator and condenser coils gather dust and dirt as the air conditioner runs. A clean filter will go a long way towards keeping the evaporator coil clean, but it still needs to be wiped down every time you do your yearly maintenance. The condenser coil can become very dirty if the area outside is dusty, so make sure to clean it regularly as well.
  • Check the coil fins – The coils inside your AC unit are covered in thin aluminum fins that can block airflow if they’re bent. We recommend buying a common HVAC tool called a fin comb that can easily bend the fins back into position rather than using your fingers, as they can be delicate.


Outside of regular cleaning twice a year, your AC system will sometimes require professional maintenance to check the refrigerant, measure the airflow, test the thermostat, and otherwise inspect every part of the system. If you’ve noticed any problems with your air conditioner, give Valley Comfort Heating & Air a call at (707) 664-7201 and our licensed HVAC professionals will take care of it for you.