7 Most Common Commercial HVAC Problems

7 Most Common Commercial HVAC Problems

How to avoid the unlucky 7, solve problems and save money

Airflow, refrigerant, leaks and obstructions are just a few of the problems that can confront a building’s heating, ventilation and air conditioning system.
They’re especially acute because so many people and businesses rely on a strong commercial HVAC system.
Many problems can be averted with smart maintenance. Simple steps like cleaning dirty filters and replacing old parts can help a commercial HVAC system live far beyond its projected life span, always welcome news for the bottom line.

A system’s life expectancy

Let’s look at common HVAC problems and solutions and see if your commercial system can match or exceed the life expectancy projected by the American Society of Heating, Refrigerating and Air-conditioning Engineers.
ASHRAE gives the life expectancy of a commercial HVAC unit here:
• Water-to-air heat pumps, 19 years
• Single and multi-zone rooftop air conditioners, 15 years
• Through-the-wall air conditioners, 15 years
• Packaged chillers, 20 years for reciprocating; 23 years for centrifugal and absorption
• Cooling towers, 20 years for wood and galvanized metal; 34 years for ceramic
• Air-cooled and evaporative condensers, 20 years
• Steel water-tube boilers, 24 years for hot water, and 30 years for steam
• Steel fire-tube boilers, 25 years for hot water and steam
• Cast-iron boilers, 35 years for hot water; 30 years for steam
• Electric boilers, 15 years for hot water and steam
Gas and oil furnaces, 18 years
Radiant heaters, 10 years for electric; 25 years for hot water and steam
• Air-to-air heat pumps, 15 years

Not the same as residential

In commercial HVAC, you deal with much larger and more complicated systems than a home with three bedrooms and two baths, for instance.
Commercial systems must be customized to serve a building properly, taking into account the usage, occupants, drainage, pedestrian traffic, exhaust systems, multiple entries and exits, and numerous other factors.
Many buildings in New York City, for instance, serve numerous purposes — retail and restaurants on the first floor, offices on the second floor, residences above. They must deal with the demands of kitchens and laundry facilities, temperature-controlled storage rooms, and a variety of users with individual thermostats.
These multiple needs require approaches and knowledge much more complex than residential HVAC.

Neglect causes many HVAC problems

Many of the problems that cause commercial HVAC failures can be avoided by basic maintenance – noticing and fixing a small problem now rather than letting it fester into a big, expensive hassle.
It’s also a very sensible way to protect your HVAC investment. Poor maintenance makes the system work harder, increasing utility bills and shortening the system’s life expectancy.
No one’s budget wants those bad hits – not to mention unhappy tenants and frustrated employees!

2 reasons to check your utility bill monthly

1) If the bill is rising sharply, you may have a problem in the system that needs investigating.
2) It’s a good reminder to check filters and other parts. With a monthly inspection you can see if everything is working well.

What problems are most likely on a typical operating HVAC system?

Here are seven that can sideline your business.

1) Slow or no airflow
Airflow issues can cause uneven distribution – too hot here, too cold there, maybe a drafty area in the building. The vents could be sending out little or no air. Or the AC could be sending warm air, not the cool air you want.
This is one of the top heating and cooling problems.
Fortunately, most of the solutions are fairly straightforward, but don’t procrastinate. Letting airflow issues build can put a sever strain on the compressor, which is the single most important – and most expensive – component in the system.
Sometimes the fix is simply cleaning or replacing clogged filters that keep the system from functioning properly. Or someone may have inadvertently put furniture or another objects in front of vents or the condensing unit, disrupting the normal flow.
Ductwork can also get dirty and dusty, or develop holes, or be dislodged by rodents seeking a cozy home inside your building. Ineffective ducts will let conditioned air escape rather than serving your building.
Occasionally the issue is something as simple as dead or dying batteries in the thermostat. Check the batteries – and replace dirty filters – and the problem may disappear.
Dirty fans and dirty coils also will gunk up the airflow – another problem solved with a cleaning rag and some elbow grease.
A problem more common with aging HVAC systems: leaks develop, with refrigerant escaping and the system losing effectiveness. The solution here calls for a professional HVAC technician certified to handle refrigerant, as required by federal law.
In some cases, the unit may not be up to the job. Perhaps the building has added new units or new purposes without making an adjustment in the HVAC system.
While most HVAC parts are very durable, weak airflow also can signal problems with the blower motor, which is responsible for pushing the air through the ducts.
If the cause of the problem isn’t immediately obvious, a technician will measure the airflow and clean filters, fan blades and coils, test the motors, inspect the ductwork and soon restore even airflow.

A note on parts

The parts most likely to fail are the ones that are used the most. They range from the compressor, a complicated and expensive component, to fan blades, which a handyman often can replace.
Other parts, such as electrical contacts and electrical contacts, require a trained technician.

2) Refrigerant issues
When the system’s refrigerant level is low, the air conditioner will blow warm or lukewarm air.
There are some signs that your system is leaking refrigerant.
Perhaps the air isn’t as cool as desired, or the evaporator coils have turned icy because they can’t keep the right temperature. Or you hear a hissing sound, the tip-off to a leak.
Don’t simply pour more refrigerant into the system. It’s only a stopgap solution, and expensive and dangerous, too.
Refrigerant is toxic and flammable
Call your HVAC technician for help.
He can use an electronic leak detector to find the leak – often in the evaporator coil. Some leaks can be repaired, but many require new parts and can be very costly.
For a more in-depth look at refrigerant leaks, see this commercial HVAC trouble-shooting guide, https://www.achrnews.com/articles/140415-hvac-contractors-guide-to-troubleshooting-cooling-systems

3) A non-stop blower
If your blower is running continuously, there may be a simple solution. Check the fan switch on the thermostat; maybe someone accidentally put it on.
Or the relay may be stuck, keeping the blower from shutting off.
Furnaces have a variety of measures to limit operation. If they are malfunctioning, a trained technician can assess the problem and offer solutions.

4) Noisy furnaces
Some furnace noises are ordinary, but others are telling you there’s a problem.
If the motor is squealing or whining, a belt or bearing may be going bad.
Other furnace noises and their meaning:
• Knocking – The vibration damper is off-kilter.
• Rumbles – The heat exchanger may be corroded or dirty.
• Scraping or grinding – The blower motor is failing.
• Struggling – the gas valve or burner may be corroded or defective.

5) Air handler
The air-handler unit contains sophisticated equipment that moves the air – heated or cooled -- through your building. Its job includes keeping your system energy-efficient and producing high quality air.
One common air handler problem is a failure to fully circulate the air. Dirty filters or obstructions that accumulate in the pathway may be to blame.
Another common air handler problem: The blower motor may be wearing down.

6) Water leaks
Water leaks signal heating and air conditioning problems.
• Pans and drains are used to collect and channel the condensate produced by air conditioners and high efficiency furnaces.
But a hole in the pan or a blockage in the drainage line can obstruct the flow, producing unwanted puddle on your floor. Left ignored, the puddles can grow and damage your floors and walls.
If not cleaned periodically, the drainage line can be blocked by dirt and debris. You can install a detector that shuts off the drain when it becomes clogged
• Leaks also occur if the drain line becomes disconnected from the drain pan.
• Leaks can result from a dirty air filter. Really!
Here’s what happens: The dirty air filter blocks ventilation, making the evaporator coils freeze, then thaw.
• Puddles also are common on rooftops where HVAC equipment is mounted. Some of it is condensate from the equipment; some of it is rainfall. Either way, the water can damage the roof if the puddles are allowed to stand.

7) Evaporator problems
The evaporator may be the culprit if the air temperature is too high or too low.
• When the evaporator coil gets dirty, it loses efficiency, requiring the system to work harder. Clean the coil and the filter and the problem may disappear.
• Or other evaporator parts may be to blame.
Some are easy to detect, such as loose evaporator fan belts that become noisy and reduce the fan’s speed.
Some of these problems can be avoided or minimized with periodic cleaning.

What are some of the problems with heating or cooling systems in buildings?

Frozen AC
As you can see, HVAC diagnosis can be complicated when looking at problems and solutions.
For example, try answering the question, Why does the inside AC unit freeze up?
There are two possible answers.
One possibility: The refrigerant is leaking. Without refrigerant the coils will eventually ice over. Maybe you hear a hissing sound, a telltale sign of a leak. But you will need a professional technician who is licensed to handle refrigerant.
The second possible cause: Something is blocking the airflow over the evaporator coils, causing them to freeze -- dirty filters, a closed vent, or furniture or curtains obstructing a vent.


• Owners rightly worry about the compressor, a vital part of the HVAC system. A problem with the compressor will ripple down the line to other components in the system.
Leaks are not uncommon for compressors. Look for oil near service ports.
Another sign is the “scrambled compressor; it begins running much more loudly than normal, indicating a leak or other problem.


The economizer has numerous benefits, so it’s important to diligently clean filters and other parts to keep it functioning.
The benefits of an economizer:
• It reduces energy consumption. Sensors detect when it’s feasible to move outside air into the building, reducing the need for expensive air-conditioning. In New York, these opportunities are limited by the weather and the seasons, but even so, the economizer’s benefits are welcome.
• In addition, these breaks mean the HVAC system will last longer and require fewer new parts.
• The economizer introduces fresh air into the building – an especially valuable improvement as more people worry about air quality after Covid-19.

Blown fuses, tripped breakers

The furnace will blow a fuse or trip a circuit breaker if the blower is working too hard.
This may be due to blocked airflow, due probably to a dirty filter, although the cause could be dirty coils, leaky ducts, closed air registers, a dying capacitor or low refrigerant levels.
Bottom line: Don’t minimize a blown fuse until you find the cause.

Blower motors

Blower motors come in two styles: single speed and variable speed.
Single-speed is a relic from an earlier era. It blows air at one speed and full capacity; then stops until the thermostat tells it to resume.
Variable-speed is more effective for most buildings It can function at high or low speeds, providing a more even feel to the temperature throughout your building. Because the blower functions at variable speed, it also uses less energy – and costs you less money.

About Lighthouse HVAC

Lighthouse is a full-service HVAC company serving commercial and residential customers in Brooklyn, Manhattan, Queens and Long Island.
Lighthouse technicians are experienced, licensed and insured. Lighthouse guarantees its work.
Available 24/7.
(718) 568-7562