AC Repair and Troubleshooting Guide


If it’s 90 degrees outside and humid, you undoubtedly look forward to being nice and cool in your airconditioned home. What would you do if the air conditioning suddenly went out? Would you know how to do AC repair? Take a look at this AC repair and troubleshooting guide because it could show you how to fix AC problems—and save yourself a lot of money.

Before you begin your residential air conditioner repair, you should know what the HVAC system contains and how the parts work:

  • Air return: the vents on the walls that allow air to return to be cooled
  • Exhaust outlets: similar to a stove fan, it draws out hot or humid air through ductwork, allowing fresh air to move in
  • Filter: the inexpensive cardboard-backed filter that traps contaminants like dust, pollen, and mold
  • Ducts: a network of passageways that transports air in or out, conditioning it as it flows
  • Compressor: the motor in the outdoor unit of a central AC system that circulates the refrigerant through the coils to cool your home
  • Coils: the evaporator coil (inside the house) pulls heat through the air to cool it; the condenser coil (outside) regulates the temperature of the AC’s refrigerant
  • Blower: activated by the thermostat, it engages the fan and blows the cooled air throughout the house

Common AC problems and what to do about them


  • High energy bills
  • Limited airflow from vents
  • Ice on refrigerant lines
  • Poor cooling
  • Water leaking from AC unit

Potential fix:
Check your air filter. Does it look clogged? Covered with dirt and dust? Replace the filter. Most are cardboard frames around foam or mesh that trap the debris. A good rule of thumb is to replace it every 30 to 90 days.


  • AC not working/won’t turn on
  • Warm or hot air (not cool) coming from vents

Potential fix:
Make sure the thermostat is on “cool” and not “heat.” Also, check the electrical panel and look for tripped circuit breakers. If the one for AC is marked “off,” then try turning it “on.”


  • High energy bills
  • Warm air coming through vents
  • Inadequate cooling
  • Lots of repairs

Potential fix:
Check your outdoor AC unit. There could be trapped debris or dirt. Try rinsing it with a hose on a gentle setting. If there’s a thick layer of dirt on the condenser, you should call a professional.


  • Icing on refrigerant lines
  • Blower motor issues
  • Damaged compressor
  • Frozen evaporator coil
  • Poor cooling

Potential fix:
Check the supply vents inside your house (even in the unused room) to see if they’re covered or blocked. Vents that are intentionally closed actually cause more problems and don’t save energy.

Maintenance tips that could help your AC work efficiently

  • Check and replace air filters regularly.
  • Keep the outdoor unit free of debris and dirt and remove anything that might block the airflow.
  • Remove the condenser’s fan cage and use a wet or dry vac to clean away debris.
  • Clean the fins and straighten bent ones with a butter knife; then brush and hose the inside.
  • Clean the drain pan on the interior unit.
  • Change the blower filter every six months.
  • Dust the evaporator coil with a soft brush and spray it with no-rinse coil cleaner.
  • Clean indoor registers and air ducts with a damp cloth and vacuum away dust.
  • Listen for odd noises and see if there’s a loose bolt or debris caught in the outdoor unit.
  • Turn off the humidifier’s water supply in the summer or turn it back to 35-45 percent.
  • Give it a break when temperatures are not extreme and turn off the cooling; use the fans instead.

Just like with most things of value, if you properly maintain your HVAC system it’s probably going to work more efficiently and last longer. If you schedule regular checkups, you may be able to avoid costly air conditioner repair.

Interested in HVAC training programs in Chicago? Contact Coyne College and train to become an in-demand HVAC-R technician in less than a year.

Things to Know About Commercial HVAC Systems


Both residential and commercial HVAC systems serve the same purpose: to cool, heat, and ventilate. However, as you would expect, commercial or corporate HVAC does it on a much grander scale. They also vary in terms of mechanisms and parts.

What is an HVAC system supposed to do?

All HVAC systems strive to keep temperatures comfortable, which is generally around 72 degrees Fahrenheit. Additionally, they aim to keep indoor humidity consistent at 40-60 percent and air quality high, with CO2 less than 1,000PPM (Parts Per Million). That means that of one million gas molecules 1,000 would be carbon dioxide, and the other would be other gases.

Although there are different types of commercial HVAC systems, they all operate similarly:

  • Air conditioner units lower temperatures by expelling hot air through HVAC refrigeration or water-cooled systems.
  • Heating systems do the opposite, using water, radiator coils, or gas to heat the air.
  • Ventilation systems use fans to circulate the air and pass it through filtration systems to clean it.

How do commercial HVAC systems differ from residential systems?

Residential systems are less complicated than commercial systems and differ significantly:

  • Size: As you would expect, commercial systems are much larger than residential systems. They also have different thermostats, condenser fans, compressors, evaporators, blowers, and dampers.
  • Location: A residential HVAC system is usually placed outside the house or on the roof, in some locales. A commercial system, on the other hand, maybe located in a building’s swamp cooler or on the roof. The latter is a great space saver, which also makes for better noise control and easier access for maintenance.
  • Drainage: An individual AC unit may just have one drain or drain tray, but a commercial system has many pipes and drains to collect condensation.
  • Mechanism: This depends on both the structure and location. A residential HVAC system is usually a standalone unit, but commercial systems are generally modular. The parts in a commercial system are located in one spot, making it easier to upgrade or replace them.
  • Equipment: A commercial system is often massive and customized for the most efficient and heating for the size of the building and its use.
  • Costs and maintenance: Commercial HVAC systems are much more expensive because of their complexity, and they should be installed, serviced, and maintained only by experienced commercial HVAC contractors and technicians.
What is an HVAC system supposed to do?
All HVAC systems strive to keep temperatures comfortable, which is generally around 72 degrees Fahrenheit.
Learn More
How do commercial HVAC systems differ from residential systems?
Residential systems are less complicated than commercial systems and differ significantly:
Learn More
What are the different categories of commercial HVAC systems?
Building size can often determine what type or combination of HVAC system works best to heat and cool it.
Learn More

What are the different categories of commercial HVAC systems?

Building size can often determine what type or combination of HVAC system works best to heat and cool it. Although there are variations, most can be narrowed down to three main categories:

  • Single split system: Popular and affordable, this system is often found in smaller commercial buildings and allows for individual heating and cooling control of each space. If it’s an office building with a server room for computer equipment or a restaurant, this would be ideal. This system features a combination air conditioner/furnace that passes air through refrigerant lines and circulates it via air ducts. However, for each space you want to control, it requires a separate outdoor unit.
  • Multi-split system: Up to nine indoor units can connect to one outdoor unit, resulting in better energy efficiency and a smaller outdoor footprint. Sensors detect temperature changes and can be adjusted as needed. However, multi-split systems take longer to install and can be more expensive.
  • VRF (Variable Refrigerant Flow) or VRV (Variant Refrigerant Volume) systems: These work best in large mixed-use buildings, such as big office buildings or hotels, where both heating and cooling of different spaces could be needed at once.
Is there an industrial HVAC installation guide?

Many business owners know they need to get a new HVAC system, but they may have little knowledge of HVAC. They might also have trouble understanding the installation quotes or equipment requirements they get from commercial heating contractors. If they follow a few guidelines, they may be more confident when choosing a contractor and/or commercial HVAC system:

  • Ask for a complete breakdown of costs. When you talk to potential contractors, have them submit price quotes that cover all aspects of installation, from start to finish.
  • Learn about the latest heating and cooling technology, system types, and manufacturers. Compare systems, costs, and benefits.
  • Remember to include the cost of ductwork in your installation budget. Ductwork and piping can add a lot to installation costs, so you need to budget for them if you can’t use existing ducts and pipes.
  • Budget for system controls, such as thermostats. Depending on your building’s size, you could need dozens—or hundreds—of thermostat control points.
  • Talk to your contractor about regular maintenance. Getting a new system installed can be costly, but not planning for regular maintenance can make it even more expensive. Ask your contractor if they guarantee their parts and labor and if they include scheduled maintenance services.
How do you become HVAC technician?

You can enroll in a Coyne College HVAC program to get hands-on instruction from industry professionals who will teach you to install, troubleshoot, and service domestic and commercial HVAC-R systems. Earn your diploma in as little as 42 weeks. You’ll be prepared for a rewarding, in-demand career that O*NET OnLine reports will grow 11 percent—much faster than average for other jobs—through 2028. Illinois expects to see job growth of 13 percent.

Contact Coyne College Chicago today to get the HVAC training you need to succeed.

Everything You Wanted to Know About HVAC Installation


An air conditioner operates by taking in warm air and pulling it over a coolant system. In an HVAC system, there is also a heating component that can be adjusted depending on whether you want your home to be cooler or warmer.

HVAC Installation Guide

The air conditioning unit is a key component of your HVAC system, especially during the summer months when the temperatures start to soar. It is important to maintain the air quality to ensure your comfort and maintain your home’s energy efficiency. If planning to update or install a new system, then this HVAC installation guide can help you select a properly sized unit, connect the air conditioner to your central heating system, determine the cost of installation, and find the best location for your AC unit.

Sizing Up the Air Conditioner

The size of the unit makes a crucial difference in terms of air quality. If the unit is too small, then the air in your home cannot be properly treated. A unit that is too big can risk undermining energy efficiency and may even shut off before the air has fully run through the system. When considering how to install an air conditioning unit, it is best to consult with a technician on everything, including matters of unit size.

The heat gain of your home also factors into the size of the unit. When inspecting your home, the technician will determine how much heat is filtered into the living space. Everything from the placement of doors and windows to the position of your home in relation to the sun affects the heat gain calculation. Knowing how much heat is regularly retained by your home will help the technician select the most energy-efficient unit for your space.

Keeping Your Home Energy Efficient

Energy efficiency is determined through the SEER, or season energy-efficiency rating, which your technician will calculate during the inspection. The rating varies depending on much electricity the air conditioner uses to operate. Higher SEER ratings mean a lower cost for you, and the technician will ensure that your HVAC system continues to maintain your home’s energy efficiency.

The Best Place for the AC Unit and Thermostat

Any AC system is liable to make some noise, so you want to consider keeping the new unit tucked away from you and your family. Try to avoid placing the unit’s outside components near any bedrooms, as this might cause some annoyance in the future. The technician will know the best place to install the unit so that you can maintain the peace and comfort of your home.

You also want to think carefully about where to install the thermostat, which allows you to set the temperature in your home and regulates the entire HVAC system. It is best to keep the thermostat indoors and away from any draftiness that could affect its readings of the overall temperature. The thermostat should also be kept away from ducts, which will direct air toward the device and likely tamper with temperature readings. To improve energy efficiency, you can install a smart thermostat that automatically adjusts the temperature reading to create optimal living conditions.

HVAC Installation Guide for Homes with Central Heating

If you have a central heating unit already in place, a technician only needs to make a few modifications to your system. There should already be a duct system that connects to your furnace or central heating system, and the air conditioner simply needs to be introduced to this ductwork. It is important to have a technician check to make sure that the ducts are properly connected. Otherwise, the system could possibly leak and reduce energy efficiency.

Even with existing ductwork, you might need to make some changes to your system to make sure that the new unit can properly function in relation to the heating system. Possible alterations include having your furnace or heating system altered to accommodate the introduction of the air conditioner and modifying the duct system so that quality air is spread effectively and efficiently through your home.

Installing New Ductwork

No HVAC installation guide would be complete without addressing what do if your house needs an entirely new duct system. Not every home has ductwork built-in, but this is not a problem for a trained technician. If your home needs to be outfitted with new ductwork, then your technician will create a floor plan and determine how to complete the installation in an unobtrusive way as possible. The best places to put ducts are spaces that are hidden from view such as closets or if you have multiple floors, attic ceilings. The technician will make sure that every aspect of your HVAC system is installed without making major renovations to your home.

The Cost of Energy Efficiency

With any new installation come cost considerations. There is not a set price for this type of renovation, and the cost of installing a new unit varies and depends on multiple factors:

  • Size of your home
  • Quality of insulation and electrical system
  • Number of doors and windows
  • Condition of ductwork

A technician will inspect your home prior to completing the air conditioning installation and can provide a cost estimate. The technician will check every element of your existing heating and cooling system to determine what is best for your home.

Build Your Expertise

There are many considerations to keep in mind when installing a new air conditioning system. As temperatures start to rise, you will want to have the perfect HVAC system to control the air quality of your home. With the help of an HVAC installation guide and a trained technician, you can ensure that your home is comfortable, energy-efficient, and ready to take on the heat. In addition to seeking out a technician, you can learn more about the finer points of heating, ventilation, and air conditioning by registering for HVAC programs at Coyne College. Our instructors have the expertise and help you become a top technician. Heating and cooling systems are an integral part of any building’s infrastructure, and through our training programs, you can gain expert-level knowledge of these essential systems.