HVAC Troubleshooting


Commercial heating, venting, and cooling systems do more than simply regulating the temperatures in the building. If there is a defect in a commercial HVAC system, it can affect the satisfaction and health of the occupants, the productivity level, and the energy bills. That is why it is crucial to have HVAC systems properly maintained. Regular checkups and maintenance of the HVAC systems help you to identify the possible faults and solve them in advance.

To help you troubleshoot problems with your HVAC equipment, we’ve created a simple HVAC diagnose app.

Troubleshooting Parts of Your HVAC System


A chiller helps to condition the air and provide a perfect environment in a commercial building. The chillers are linked to various problems, but here are the most common issues.

  1. Oil failure

There will be an oil failure if there is a refrigerant leak that leads to low oil in the chiller, if the oil pump is damaged, or if there is low superheat in the chiller.

  1. Low/High-Pressure issue

Low pressure is normally caused by a broken power assembly capillary, insufficient water flow, mud coating on the tubes, a blocked water filter, or low refrigerant.

The chiller can also encounter a high-pressure issue if the water-cooled condenser has a buildup of minerals that affects the water quality, or if the condenser has little or no flow. On the other hand, the temperature of the chilled water tank might be over 80 degrees Fahrenheit.

  1. Starter trip or blown fuses

This can happen if the motor, wires, or compressor are over-amped or shortened. The best solution for this is to check for shorts or grounds and fix them accordingly.

  1. Freeze stat

This will occur if the water flow is poor or if the thermostat has been set lower than the required level.

  1. Lack of flow

There might be a weak flow if pressure or flow switches in the water circuit are not getting the right amount of flow. Also, the water valve might be off, or the water filter might be blocked. Though in most cases, the flow switch paddle is broken.

  1. The chiller is running but doesn’t reach the thermostat settings

Here, the evaporator might be iced up from the inside, or the antifreeze could be broken. Also, the system load could be too heavy for the chiller to handle.

These are the common issues you would expect to experience with commercial chillers. Always understand how the chiller works and how to identify each problem with ease.

Chillers maintenance tips

Proper maintenance of your chiller will help you to avoid problems with it. Here are some maintenance tips.

  • Keep a daily report. A daily log of the chiller plant helps you to maintain its efficiency so that you will know all the operating condition history such as the flow rates, pressures, temperature, and fluid level. You can depend on remote monitor technology to inspect the unit.
  • Treat the condenser water often to avoid corrosion, scaling or biological growth.
  • Avoid changing the flow rate of the chilled water, which can affect the performance of the chiller. Ideally, maintain a flow rate of between 3 FPS and 12 FPS.
  • Clean the tubes regularly to enhance the heat transfer efficiency.
  • Lower the temperature of the condenser water entering the chiller.
  • Evaluate the compressor lubrication oil annually. Preferably, send a sample to a lab for chemical analysis. This will help you to decide if you need to change the oil or not.
  • Inspect the motors and start operation for any fault.
  • Install variable speed drives for energy saving benefits.

For complicated HVAC issues contact a local HVAC contractor.


During cold seasons, boilers play a huge role in commercial buildings, so it is important to understand the common problems that affect the boilers, and how to solve them.

  1. System overheat

When there is a system overheat with the boiler, there could be an issue with the system controls. If that is the case, check the temperature settings, safety switches, or the voltage. Also, the control thermostat might have failed, or the high-limit thermostat could be ON. You can check the temperatures in this case.

  1. Failure to meet the system load

If the boiler fails to meet the system load, the potential problem could be that the boiler thermostat hasn’t been set correctly. Check the settings of the thermostat to fix this issue. There could also be an issue with the combustion. Ideally, check the combustion quality, the flue, and the flame to ensure that the combustion is perfect.

  1. Ignition failure

If the boiler doesn’t ignite, it could be as a result of various defects. First off, the internal controls of the boiler might have failed, which can be solved by resetting or replacing the controls. The boiler could also be overheating, or maybe the cut-out has not been reset. Alternatively, the pilot flame might be missing, or the supply fuse could be isolated or blown. In other cases, the main burner might not be igniting.

  1. Fumes issues

If there are fumes in the boiler room, there could be issues with the combustion. Also, the combustion might be experiencing poor airflow. To solve this, inspect the chimney and the boiler room to ensure that the combustion is correct.

  1. Overheating and noisy boiler

There could be a poor circulation in the main circuit. The solution is to vent the system accordingly. If there is a low discharge pressure in the shunt-pump, check for any obstruction in the piping.

  1. Continuous firing

If the boiler fires nonstop, the main issue might be a faulty thermostat. You can inspect the thermostat and replace or repair it where necessary. If there is an issue with the wiring, inspect and repair as required. The control valve could also be sticking or faulty. You can replace it to solve the problem.

Other possible problems with commercial boilers could be a fault in the flue gas system, or the boiler might start but the flame goes out afterward, as well as high or low water temperatures. If you can’t fix any of them, contact a qualified commercial HVAC contractor.

Cooling Towers

The cooling tower is basically a heat exchanger that utilizes air and water to shift the heat from the AC units to the outdoor environment. Here are the common HVAC cooling tower problems.

  1. Leaking issues

Leaks are commonly experienced with cooling towers, which end up damaging the building. Ideally, find a professional contractor to inspect the cooling tower for any possible leakages.

  1. Original coating delamination or breakdown

The original coating of the cooling tower could de-laminate or break down over time. In this case, water will be trapped in the system, which then leads to erosion or corrosion of the unit’s parts.

  1. Issues with the water quality

The cooling tower could also experience poor water quality, which could be as a result of extreme corrosion of the interiors. If this happens, you will need to hire a contractor to replace the unit or fix it accordingly.

Maintenance tips for the cooling tower

  • Conduct a regular chemical or water treatment to eliminate the contaminants and other corrosive elements in the unit.
  • Clean and prevent any blocked spray nozzles. Ideally, install clog-free nozzles to fix this problem.
  • Maintain an adequate airflow in the tower. Clear any debris that is at the outlet or inlet of the tower. Also, inspect the fan blades, fan pitch, and gearbox for any faults.
  • Check that the pump performs perfectly. The best way to ensure this is by checking for clogged strainers, loose bearings/connections, faulty vibrations, and any other fault that could affect the water flow.
  • Conduct a preventive-maintenance program regularly.
  • Limit the temperature of the water leaving the tower.
  • Operate the cooling towers at the same time.

If the problem is overly complex, contact a professional for further assistance.

Cooling Tower Pumps

The pumps that serve the cooling towers might also be faulty, which will affect the entire cooling tower unit. The most common issue with cooling tower pumps is loud noise, which sounds like pumping marbles. The problem here could be an induced draft or a forced draft cooling tower. Also, negative suction pressures can lead to pump noises.

If the component is imbalanced, the components are rubbing on each other, the coupler is misaligned, or the base plate and motor are not installed properly, there can be a mechanical noise in the pump.

A liquid noise is caused by the movement of water in the pump. This can be caused by a flow separation, water hammer, cavitation, or turbulence energy due to a high flow velocity.

Tips to eliminate the noise issue

  • Increase the liquid pressures to reduce flashing and decrease the suction lift. Here, you might have to lower the pump and raise the tower, or simply straighten the suction piping so as to limit the friction losses.
  • Decrease or increase the pump speed to limit the system resonance of the liquid or mechanical noises.
  • Inject a small amount of air into the centrifugal pump suction to provide a shock absorbing cushion and limit the cavitation noises.
  • Adjust the pump to increase the clearance between the diffuser vanes/casing cutwater and the impeller diameter.
  • Eliminate vortexing in the tower pan. You can add a baffle assembly to prevent vortexes forming. Always contact a professional contractor if you fail to solve noises that come from the cooling tower pumps.

General HVAC Troubleshooting

Commercial HVAC systems can encounter the following problems:

  1. Unpleasant odors or poor indoor air quality

If there is a bad smell or the air quality in the building is poor, there could be a problem with the filter or there might be a gas leak. A bad smell will be emitted when the parts of the unit overheat, the air filters are dirty, stagnant condensed water is in the unit, or melting debris gets into the ductwork from the heat exchanger. Inspect the system and eliminate those common errors in the system as soon as possible. You can call a professional if you can’t find the cause of the smell.

The IAQ can also be affected by a faulty damper, which should be checked several times throughout the year. The damper stops the compressor when the air temperature outside is lower than a specified point. When these dampers are not cleaned and perfectly lubricated, they tend to stick to each other. This then overloads the cooling coils and prevents the unit from cooling itself.

  1. Imbalanced Airflow

In most cases, holes or cracks in the ductwork can lead to inconsistent temperatures from one room to another. When the temperatures are variable, the system uses more energy to replace the lost airflow, leading to high energy bills.

Check for any cracks, sags, or separation in the ductwork to identify the cause of the leak. If the ductwork is insulated, you can check for any dirty spots on the insulation. Ensure that any leaks are corrected as soon as you identify them. Since it might be challenging and difficult to spot a leakage in the ductwork, it is best to contact an HVAC expert.

  1. Inefficient system

A lot of people end up replacing the commercial HVAC unit when they realize any sign of inefficiency. Specialists point out that the efficiency of a commercial HVAC unit can be highly improved by cleaning the condenser and the evaporator coils. Ideally, ensure that the coils in the system are cleaned twice every year. This helps to eliminate any debris or dirty layer on the coils, which might reduce its performance.

  1. Loud noises

These systems will make loud noises, if there is an imbalanced system, or if some elements are blocking the free flow of air and water inside the unit. A well-balanced pressure flow can help to get rid of any strange noises produced by the system.


Most of the commercial HVAC units work differently from the regular units used in houses, because they are designed to work for long hours and cover a bigger surface area or building. When the unit has various faults, it will affect the air quality in the building and also lead to increased energy bills. If you do not find the solution when carrying out the HVAC troubleshooting, always call a professional for further help.