13 Common Commercial HVAC Problems and Solutions

HVAC systems are very reliable in performance. However, this does not mean that they do not have limitations. Whenever your HVAC system has a problem, it is often a stressful encounter that should be dealt with as soon as possible.

In places where the summer temperatures are relatively warmer, losing your HVAC system to common problems can even force you to shut down your place of work or business due to unbearable conditions.

Common HVAC issues include ventilation, air conditioning and heating problems which arise through the various parts of the system.

I recommend that you have a basic knowledge of the common HVAC problems as well as their solutions to ensure that your system is functional at all times. Some of the problems may be easy to handle and therefore you may offer the solutions yourself.

However, for the more complex problems, you should hire a local HVAC professional. When the HVAC unit is non-functional and a service call has been placed for a professional to deal with the problem, there are common parts which should be checked. The common problems of each part and their solutions are discussed below.

The Common Problems and Solutions of Various Parts Of The HVAC System

1. Condenser fan motor

The condenser fan motor features the contactor which engages when there is need for cooling so as to create an electric connection. This in turn starts the motor. Contactors are also found in both the compressor and the blower motor. The common issue with contactors in the condenser fan motor is simply wearing out. Pitting also forms on the contactor which makes it difficult for the passage of electrical current and therefore the condenser fan motor may fail to start. Capacitors are another part of this motor which may burn out and inhibit the HVAC system’s functionality. The capacitors provide the compressor with a slight increase in starting torque.

Check on the contactor and the capacitors

Contact a technician to check on the condenser fan motor in case your system is not cooling the room, so that they can check on the contactor and replace it if necessary. The technicians will also replace the capacitor if it is burnt out.

2. Evaporator blower motor

The evaporator blower motor also features a contactor and capacitors which should be checked. Another common problem is a blown fuse. This problem is also common to the compressor and the condenser fan motor. The fuse protects the motor against overheating when the system is heating the environment.

Replace the blown fuse

If the HVAC system is not functioning, the breaker might have flipped off and will therefore require replacement. It is best to have a technician do the replacement if you do not have the knowledge and ability to do so.

3. Condenser Coil

This is placed outside together with the compressor for exposure to the outside elements. This implies that they get dirty often and need to be cleaned at least yearly, which can be done using a water hose when the system is not operational. If the grime and dirt get worse, the HVAC system will have to be cleaned by a technician who will have to use a chemical cleaner.

Increase airflow to the condenser unit by cleaning

Apart from the chemical cleaning solution, you can clear any dirt or grime from the condensing unit’s exterior since it may be blocking the airflow. Some of the debris may come from mowed grass which collects on the exterior of the condenser, and by clearing it; you may solve the system’s airflow issues. Tall plants that are closer to the condenser may also block the airflow. They should be trimmed back or removed completely.

4. Thermostatic expansion valve

The thermostatic expansion valve signals the HVAC system on what is supposed to be done and when it should be done. In some cases the thermostat may turn off accidentally or has the wrong settings, so before contacting any help, ensure the thermostat is on.

Check the batteries and ensure the thermostat is on

If the thermostat is not lit up, the thermostatic expansion valve may be non-functional and the batteries should be changed. You should also make sure the thermostat is on and the settings are correct before concluding that the thermostatic expansion valve is problematic and finding a technician. Contact a professional to handle your situation if it appears more complex.

5. Compressor

The compressor is the HVAC unit’s main part (the heart of the system). When the system is undercharged with refrigerant liquid, the compressor runs hot and eventually quits operation. When it is overcharged, the liquid refrigerant gets back into the compressor which leads to liquid slugging.

Ensure the compressor has the proper amount of refrigerant liquid

If you are not sure about of the correct refrigerant, talk to an HVAC technician who will recommend the right amount. It is vital for the A/C system to have the correct amount of liquid refrigerant for the effective performance of the compressor.

6. Evaporator Coil

Returns from blocked air or air filters that are clogged may limit airflow in the evaporator coil, causing it to freeze up. This problem may also be caused by low refrigerant levels. On split units, the evaporator coil is placed in the roof (attic). On a package system, the coil is placed outdoors with the rest of the HVAC system.

Clean the Evaporator coil

If the evaporator coil is placed in the attic, cleaning will be needed only when suggested and this will be about after every three years or more. The coil placed outside of the system also needs cleaning at least once every three years. In case of a cracked evaporator coil, you will have to find an HVAC technician to fix it.

7. Filters

The HVAC unit filters get clogged and dirty with time. When this happens, the filter should be changed. When a clogged filter is not changed, the airflow is reduced and this causes the system to freeze. Hold a filter up to the light to check whether light passes through it. If the light does not pass through, the filter definitely needs to be changed.

Change Air Filters

This is one of the most preventable issues, since you only need to remember to change the air filters. The furnace filters should be changed often so as to prevent problems. The inexpensive filters should be changed monthly for efficient performance of the HVAC unit.

8. Cooling tower

One of the most common problems associated with the cooling tower is leakage of the refrigerant liquid. Leakages may be result from the vibrations of the system when it is operating. Unfortunately, leakage of the refrigerant liquid in the evaporator coils and the condenser cannot be repaired.

Find a HVAC technician to charge the refrigerant

If the leakage occurs at any other part apart from the evaporator coil and the condenser, a technician will offer appropriate help. They will remove the remaining refrigerant liquid and charge the levels back to the proper amount.

9. Duct system

A common issue in the duct system is caused by grime as well as other organic materials which build up within the lines. This causes water to flow back in and eventually overflow the drain pan. This, in turn, causes damage to the components of the system. The duct system often becomes clogged with algae or dirt and when the water fills up the drain pan, it can leak over to the entire system and lead to damage.

Check the entire duct system and clean the drain line

HVAC systems have a water-safety switch to stop their operation if the water is in danger of leaking into the house and damaging the floors and ceiling. You should also check for water in the drain pan under the system since it helps you to know whether the drain line is clogged with dirt. The drain pan should simply be emptied and the drain line flushed out to solve the problem.

10. Pumps

It is not usual to find ice either outside or inside the heat pump or the central A/C which includes the outdoor unit, indoor unit and the interconnecting line-set. However, icing-up of the indoor coil may be possible if the unit is operating in very cold weather conditions or when the thermostat is adjusted to an extremely low temperature. This causes icing up within the pumps which makes them less functional. Heat pump owners who are new to them may think that the unit operates at all times since longer operation times are new to them, as is the lower temperature generated by a heat pump. In extremely cold weather conditions, a properly functioning heat pump operates almost continuously and that is how it is designed to function. This should not be considered an issue.

Ensure the temperature level is appropriate

Always maintain the temperature above 70 degrees when the system is operating. Turning below 70 degrees could cause the indoor coil to freeze up or frost and cause the duct-work to sweat. This might lead to damage on the walls or the ceiling. If the air conditioning is required in winter, especially in businesses and restaurants, a low ambient kit is needed and should be installed by a HVAC professional to ensure that your pumps are performing effectively.

For more pump problems and solutions see common HVAC pump problems and solutions.

11. Controls

Controls such as the safety switch in the drain pan placed under the HVAC system should be checked. A common problem which is experienced in attics involves boxes which are being moved bypassing the switch, which could cause a huge amount of water damage. Another control that can be a slight problem is the thermostat switch which you should make sure is on as it may be switched off accidentally which may lead you to conclude that the unit is failing.

Avoid bypassing the safety switch and ensure the thermostat is switched on

Avoid bypassing the safety-switch in the drain pan under the system to avoid water damage. Also make sure the thermostat is switched on and is set correctly.

12. Boilers

Boiler systems that feature circulation pumps which have couplings have a common problem which is the breaking of the couplings which leads to loss of the hot water circulating through the boiler’s water loop. This limits the system’s functionality.

Contact a specialist with the skill to replace

If have any problem with the boiler, contact the plumbing technicians and the HVAC professionals and ensure that they specialize in dealing with boiler issues. The perfect solution involves replacing the broken coupling so as to restore the flow of water into the water loop. It is very important to ensure that both the pump motor and the circulation pump bearing assembly have the appropriate lubrication and are moving freely before the replacement of the coupling.

13. Chillers

Chillers are maintained and inspected often. Despite regular inspection, a common problem involves degraded performance over time due to leakages and clogging by dirt within the system. Another common problem on chillers is the accumulation of scale over time.

Cleaning and ensuring there are of leakages

The chiller may need either mechanical cleaning or chemical cleaning depending on the intensity of the clogging. Mechanical cleaning gets rid of mud, sludge, algae and other loose materials from the smooth-bore tubes. Mechanical cleaning includes brushing the tubes, removal of the water-box covers, and flushing the chiller using clean water. For the tubes that are internally enhanced, it is recommended to seek professional advice regarding the recommendations for mechanical cleaning. Chemical cleaning, on the other hand, removes scale from the chiller. For chemical cleaning, contact a professional who will recommend the correct chemical solution for the job. After the chemical cleaning, the chiller should have a thorough mechanical cleaning.


Being knowledgeable about the most common problems on the various parts of the HVAC system together with their appropriate solutions is greatly beneficial. The information above will guide you in detecting any problems that may arise on your unit and also help you in employing the most appropriate solutions to ensure that your HVAC system always runs efficiently.

You can also check out our HVAC diagnosis App to help you narrow down the issues with your HVAC equipment.