How to Troubleshoot Common HVAC Problems (Heating, Ventilation, and Air Conditioning)

Current HVAC systems (heating, ventilation and air conditioning) are more effective and sophisticated than ever before. That means that to install and maintain HVAC systems , you probably need expensive, high-tech diagnostic tools and equipment. But many of the most frequent complaints about deficiencies in the operation of heating, ventilation and air conditioning systems can be remedied with a little research and simple and straightforward repairs. Here's how to solve common HVAC problems:

Common HVAC Problems: A / C works but does not cool Solution:

One of the common problems of HVAC and probably the number one summer complaint. Although most homeowners will have already reviewed the most common causes before calling for HVAC repair staff, it should be re-checked. Make sure the thermostat is turned on and set below room temperature. If there are separate indoor and outdoor units, make sure they are both on. Check all circuit breakers in the home and reset the buttons on the units. If the air conditioner has a condensate pump, make sure it is working. Some condensate pumps have a safety switch that shuts off the outdoor unit if the pump fails.

If both air conditioners seem to work well but still do not cool the space, make sure all windows are closed and the ventilation system inlets and outlets are open and unobstructed. Check the filter and clean or replace if necessary. Make sure there are no air leaks in any conduit.

If all of these conditions are met, potential HVAC problems will have been reduced to a few:

Low or restricted refrigerant level. Add more coolant or repair coolant lines.

Defective metering device. Replace it.

Reverse or compressor valves deficient. Replace them.

Common HVAC Problems: The outdoor unit does not work Solution:

This is another common HVAC problem. Some of the causes can be serious and costly repair. Possible simple causes include improperly adjusted thermostat, emergency shut off or circuit breakers tripped. Also an external disconnection that has been turned off.

If the unit has a condensate pump, it may be disconnected or the safety switch may be open. In addition, the unit could be "locked", meaning that there is a safety device that prevents its normal operation. Reset by switching off the circuit breaker for one minute, then reconnecting it and waiting 10 minutes for the unit to activate.

Beyond such simple repairs, one of the safety devices may be open. Check any safety device for low pressure and low temperature as well as for high pressure and high temperature and see if they have been fired. If so, you will need to diagnose the thermostat, the contact, the delay relay , the thermostat wire, and the control module to determine which is failing and needs to be replaced.

Everything seems to work fine, but the airflow in the ventilation system is weak Solution:

Of all the common problems of HVAC, this is the one that with more possibility can be corrected with a simple repair. Most of the time, poor airflow is due to the dirty air filter. Current high efficiency filters are so effective in filtering fine dust and allergens that when clogged they can cause severe restrictions on air flow.

Another common cause is dirty, blocked or closed ducts. Ensure that all ventilation system inlets and outlets are open and unobstructed, that gates are open, and that no dirt or debris blocking any of the ducts. You may need to insert a camera into the duct system to make sure they are not blocked. While checking to see if they are blocked, check that the duct system is properly sized and installed. Failure to do so may cause problems.

The most serious repairs by a deficient air flow are usually made in the blower, the fan or the cooling coil. The defective motor of a blower should be replaced, although sometimes a simple cleaning of the blower wheel will solve it. Also the interior coil may be defective, as it freezes and restricts the air flow. If so replace it, but first see if the dirty coil needs cleaning to keep it working.

Check that the fan speed is not set too low. Re-adjust to proper speed if necessary. Other problems that could reduce airflow - because they affect fan speed - are a loose, worn fan belt and pulley sizes are incorrect. If necessary, check them and repair them.