April 8, 2019

When your home’s HVAC system breaks down, the cost of an HVAC repair is an unexpected expense and can put a dent in your household budget. How can you determine which problems you can fix yourself and which require a pro? This guide to repairing a residential HVAC system will help you understand the signs of minor or major problems, when it’s time for repairs, or if the unit needs replacing.

Common Air Conditioner Problems

A well-functioning air conditioner is vital to survive the sweltering summers in Las Vegas. Here are some of the most common problems that occur with air conditioners.

The AC is Blowing Hot Air

If your air conditioner is blowing hot air, the cause could be one of the following:

  • A dirty air filter. When the air filter is clogged, it restricts airflow and starves the system of air. A dirty filter can also cause the system to freeze over. Replacing the filter should solve the problem. If you suspect the system has frozen over, turn the air conditioner off and let the system thaw for a few hours and then restart it. If it’s still not cooling, turn it off and call an experienced HVAC technician to help resolve the problem.
  • A blocked condensate drain line. If air isn’t moving freely through the drain line, condensate cannot drain from the system. This results in water building up on the evaporator coil that will eventually freeze. Left unattended, the coil will become a block of ice and the air conditioner will struggle to produce cool air. Turn the air conditioner off and wait for the ice to melt before cleaning the condensate line.
  • The refrigerant is low or there’s a refrigerant leak. Don’t attempt to refill refrigerant yourself as under or overcharging refrigerant will negatively affect the unit’s performance. A professional HVAC technician will do a leak test, repair any leaks found, and charge the unit with the correct amount of refrigerant according to the manufacturer’s specifications.
No Air Is Coming Out of the AC

If the air conditioner is running but no air is coming out, check the following:

  • Outdoor unit. Dirt, leaves and other debris can accumulate around the outdoor unit and will obstruct airflow. If after clearing away debris the AC is still not functioning, call a technician.
  • Air vents. A thick layer of dust and dirt can build up on the air vents that blocks the flow of air.
  • Compressor. When the AC compressor fails, it is no longer able to pump refrigerant through the system. A failed compressor is a serious problem and is likely to need replacing.
  • Condensate drain line. A blocked condensate line can prevent air from flowing through the system.
  • The outdoor unit fan. If the fan in the outdoor unit is not running, it often means a breaker has tripped. So reset it and your AC should be up and running again. If, however, you hear a clunking noise, this could indicate a more serious issue like an unbalanced fan blade. Turn the AC off immediately and call an HVAC technician.
Unusual Noises

It’s normal for an air conditioner to make a sound when it’s on. If, however, you’re hearing unusual noises, don’t ignore them. It could be the reason for an HVAC repair. Here are the types of noises that indicate a problem:

  • A clanging noise usually means a part is loose or the indoor blower is unbalanced.
  • A hissing sound could mean refrigerant is leaking.
  • A buzzing noise could indicate an electrical issue. This is a hazard as it can spark a fire. If you suspect an electrical problem, turn off the unit and call your HVAC company to inspect the system.
  • A rattling noise means there may be debris like stones stuck in the condenser unit or a loose bolt or screw is rattling around somewhere in the unit.
  • A screeching noise is likely due to a failing fan motor or a problem with the compressor.
  • A clicking sound is normal when switching the AC on and off. However, persistent clicking while the unit is running is a sign of a defective or failing thermostat.
  • If any strange or loud noises are coming from the outdoor unit fan, turn the system off immediately! It could be an unbalanced fan blade that can cause major damage to the system. Do not attempt to replace the fan blade yourself. This requires an experienced technician who will find the exact replacement and correctly balance the blade for safe operation.
A Foul Odor

In addition, if your air conditioner is emitting a nasty odor, try to identify the type of smell and where it is coming from. Some odors are innocuous while others are a health hazard.

  • An odor that smells like stinky feet or socks usually points to stagnant water in the drain pan.
  • The nasty smell of decomposing matter is unmistakable and means you have dead critters in the ductwork. The bacteria from rotting carcasses will circulate through your home’s air and can cause illness. It’s best to have the ducts professionally cleaned.
  • A moldy or musty smell means mold or mildew have grown on the evaporator coils or in the ducts. Mold spores floating through the air also presents a health hazard. Humidity contributes to bacterial growth. Invest in a dehumidifier or place a UV lamp near the evaporator to kill bacterial growth on the coils.
  • A skunk-like or rotten egg odor is a sure sign that you have a gas leak. Natural gas is odorless so manufacturers add a chemical called methyl mercaptan to give it that foul smell. This is a dangerous situation as natural gas is a volatile explosive. Turn off the gas, evacuate the house, and call 911 who will dispatch the fire department in a case like this.
  • A burning or gunpowder-type of smell is a sign of an electrical issue. This could be an overheating motor, a short on the circuit board or fan motor, or some other mechanical problem.

Common Furnace Problems

Even though Las Vegas is known for its heat, when winter rolls around temperatures can be surprisingly chilly. The last thing you want is to be caught without heat. It’s no fun when you need an HVAC repair in the middle of winter. Here are some common furnace problems.

The Furnace is Not Starting

Struggling to start the furnace is frustrating. Here’s how to troubleshoot a furnace that refuses to start.

  • Check if the thermostat batteries are dead.
  • Check the circuit breaker for a blown fuse or tripped breaker.
  • If it’s a gas furnace, you may have run out of gas or simply forgotten to open the gas valve.
  • The pilot light might be out. If you’re battling to restart it, perhaps dust is blocking the opening preventing it from igniting.
  • If your furnace is old, it may have finally given out and it’s time to replace it.
No Heat From the Furnace

When there is no heat from the furnace, the cause is often one of the following:

  • A clogged air filter.
  • The heat registers are closed. Opening the heat registers will allow warm air to start flowing again.
  • Leaky air ducts bringing in cold air from outside. Contact your HVAC contractor to find the leaks in the ductwork and seal them.
  • If the thermocouple or flame sensor is defective, it won’t ignite the burners.
  • Check that the thermostat is set to “heat” not “cool”, and that the fan is set to “auto” not “on’.
  • Sometimes all that’s needed to restart your furnace is press the reset button.
The Furnace is Not Producing Enough Heat

Equally frustrating is a furnace producing lukewarm heat. The problem often stems from a dirty air filter, a faulty ignition switch, or a furnace that is incorrectly sized for your home.

The Furnace Blower Runs Continuously

When your furnace blower runs continuously, the problem lies with a faulty limit switch. The limit switch shuts the furnace off when the desired temperature is reached. When this malfunctions, your blower will run continuously.

There’s a High-Pitched Noise

A high-pitched squealing noise coming from the furnace could indicate a problem with the blower belt or blower motor bearings. The solution may be as simple as lubricating the belt. That’s one type of furnace repair that you could handle yourself. If that doesn’t work, call an HVAC technician to fix the problem.

HVAC Repair: Thermostat Problems

If your HVAC system isn’t heating or cooling properly, the first thing to do is to check the thermostat for the following problems. These issues are usually easy to fix.

  • The thermostat is switched off.
  • The thermostat hasn’t been switched over to “cool” or “heat” during a season change.
  • The batteries need replacing.
  • The temperature needs to be adjusted a few degrees higher or lower.
  • Check the location of your thermostat. A thermostat that receives direct sunlight or is located near drafty windows and doors will affect the temperature regulation.
  • The thermostat is dirty leading to inaccurate temperature readings. Open the cover and dust the inside with a soft brush.

What HVAC Repair Can I do Myself?

Regular HVAC maintenance is crucial for keeping your HVAC system running smoothly. You should schedule an annual service and seasonal tune-ups to keep your unit in tip-top condition. It’s worthwhile signing up to a regular maintenance plan with your local HVAC contractor. There are, however, a few HVAC repair tasks you can perform yourself:

1. Change the air filter regularly.
This keeps the air flowing freely through the system.

2. Check the condensate line.
The condensate line can become clogged with algae, bacterial growth, and debris. Cleaning the drain pan is easy and you can unblock the drain line by shoving a garden hose in it and flushing out the dirt, pouring hot water down the drain, or using a small hand snake or drain cleaning brush. If the drain is so badly clogged that none of these methods work, it’s time to bring in the pros to clear the blockage.

3. Dust around the air vents and make sure you have no furniture blocking the vents.

4. Keep an eye on the outdoor unit and if leaves and debris are covering, clear these away.

5. If your outdoor unit is enclosed by a fence or has trees or shrubs near it, make sure there’s enough breathing space around the unit. Also, keep at least 2-3 feet of space around the unit to allow sufficient airflow.

When to Replace Your HVAC System

If you’re unsure as to whether you should repair or replace your HVAC system, here’s how to determine which route to take.

Have you noticed your energy bill creeping up? When an air conditioning unit no longer functions efficiently, it uses more energy resulting in high electric bills. Have an HVAC professional assess your unit. They will be able to advise whether the unit needs repairs or if it’s time to replace it.

The average life expectancy of an air conditioner and a heat pump is 10-12 years and furnaces last 15-20 years. If your HVAC unit is old and giving persistent problems, it’s time to replace it. Old HVAC systems, just like old motor vehicles, reach a point where funneling money into endless repairs is no longer worth it. Use the 50 percent rule when thinking about the cost of an air conditioner repair. When the cost of repairs approaches 50 percent of your HVAC system’s value, it’s time to replace the system.

There are benefits to replacing the heating and air conditioning system. Newer HVAC systems are more energy-efficient. When choosing a new HVAC system, ask about the SEER rating of air conditioner units and the AFUE rating of a furnace. Aim for a minimum SEER rating of 15 and AFUE rating of at least 81 percent.


For answers to your HVAC problems, refer back to this guide to repairing a residential HVAC system. If an HVAC repair is necessary, use a highly trained, licensed HVAC contractor.

In the Las Vegas area The Cooling Company employs only EPA-licensed and trained technicians trained with years of experience. From customer service to every aspect of residential HVAC repairs and maintenance. Our HVAC services include duct cleaning and sanitizing, drain pan cleaning, refrigerant leak detection, indoor coil defrost, thermostat checks, and repairs to electrical wiring.

Call us at (702) 567-0707.

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