Potential Reasons Your HVAC System Isn't Blowing Out Cold Air Or Hot Air

Posted on: 29 August 2016


A central air conditioner system typically has the ability to act as both a cooling and a heating system thanks to the fact that the interior air handler part of the unit is located within the furnace. The dual function system offers convenience from an operational standpoint but can make things more complicated to diagnose when a problem arises.

If your air conditioner suddenly stops blowing out cold air, checking to see if the furnace is also experiencing problems can help you diagnose your issue—and vice versa when the furnace stops blowing out hot air. Here are a few potential reasons your HVAC system can stop blowing out cold air or hot air—and how an air conditioning services company can help.

No Cold Air

The first place to check is to make sure your air filter has been cleaned or changed recently. The filter helps clean the incoming air so that you don't have a bunch of dust and particulates floating around. Filters will eventually become blocked by all of the filtered particulates and will prevent air from properly circling through and out of your air conditioner system.

If the filter is fine, check the evaporator coils located within the furnace to see if the coils have frozen up. You will literally see ice on the surface of the coils. The freeze up can be a sign that the coils need cleaned or that your system has a problem with the refrigerant chemical that fuels the cooling.

You can clean the coils by turning off the power to the unit, giving the coils time to naturally defrost, and then applying a no-rinse foaming cleanser that's available at most hardware stores. Try running the unit again after the cleaning to see if the coils still freeze. If your system freezes again, call in an HVAC tech to check on the refrigerant levels and to make any adjustments that are necessary.

No Hot Air

A non-functional furnace can also arise from a clogged air filter so check there first. You can also double check to make sure that the thermostat is set correctly and that the unit hasn't tripped the circuit breaker.

If you have a gas furnace, check to make sure the pilot light is staying lit properly. Does the light come on but quickly go out? Call in an HVAC tech (like those at Thompson Heating & Air Conditioning Inc) to repair or replace the affected parts.

Both electric and gas units can stop blowing out warm air if the blower fan goes out. The blower fan is what circulates air through the furnace to be heated and then pushes that hot air out of your vents. Electrical issues or part failures can cause the fan, its motor, or both to fail and stall your heating system.