Home AC Cools Then Blows Warm

There are a number of reasons why your home AC unit blows cool air then constantly blows hot air. Hot air may be flowing into your home because of internal damage inside of your air conditioning system. Warm air may also enter your house because of the settings on your thermometer. This guide will give you a better idea as to how your heating and cooling system goes from blowing cold air to warm air.

Air is blowing but it is not cold

Sometimes, homeowners will find situations where their HVAC system blows air through the fan, but it is not cold air. In fact, the air being pushed through the ductwork is at room temperature. The air may be slightly cool but not what is typical when the air conditioning system is running at its peak efficiency.

Refrigerant Issues

In this situation, typical causes are related to refrigerant problems. If your home’s air conditioning system is older than 10 years, it is a likely scenario that your refrigerant is leaking. This explains the air temperature not being cold enough for your liking. If your air conditioning system’s refrigerant is not fully charged, the unit cannot cool the air efficiently and effectively. This leads to an uncomfortable home especially when the outside temperatures are extremely hot and humid.

Thermostat Issues

Sometimes, homeowners may experience warm air blowing through their ducts, and at other times of the day, cold air is blowing through their ductwork. If you are experiencing this situation, it may be related to an improper setting on your thermostat. A simple check is to see if your thermostat setting is turned to “On” versus “Auto”. When the thermostat is set to “On”, the fan in your HVAC system runs continuously. This means it runs when your air conditioner is actively cooling air as well as when it is not. In the latter case, the air being pushed through your ductwork is not cool air. The simple fix is to flip your thermostat switch to the “Auto” setting.

Other Air Conditioning Problems

Clogged outside unit

When debris from outside (leaves, bushes, mulch, etc.) gets clogged in your home’s outdoor unit, the performance of your air conditioning decreases. As leaves or bushes block your HVAC unit, they trap heat inside of the cooling system. Also, leaves and other debris gather moisture. As they clog the outside unit, the moisture on the debris will cause the outdoor unit to rust as time passes.

One way to combat debris from gathering in your AC unit is to trim all bushes near the outside cooling system. Trimming the bushes around the air conditioning system will help eliminate a build-up of leaves on the HVAC system. You could also put a leaf guard cover on your outdoor unit. This cover is made of a mesh-like material that still allows air to flow but stops leaves and other debris from entering your air conditioning system.

No power

If your heating and cooling unit does not have power, then cold air will not blow into your home. There are multiple reasons why this may occur. For example, the circuit breakers in your home may be tripping because the circuit breaker itself is faulty. Another cause may be that your air conditioning system has something wrong with it and is causing the circuit breaker to flip off. In this scenario, there are many items that may be causing this electrical problem. It is highly advised that homeowners do not try to troubleshoot this on their own. Contact a qualified HVAC technician to diagnose and repair this problem.

Another common issue that we run across is the emergency power switch is inadvertently turned off. When the emergency power switch to your HVAC system is switched off, your system does not receive any power at all. This is a simple fix that any homeowner can check before calling in a professional. The emergency shut-off switch is typically found at the top of the staircase to your basement. Also, this switch typically has a red cover plate clearly marked “emergency shutoff switch”. If you find your emergency switch in the “Off” position, turn it on and then see if your HVAC system starts up. If it continues to not have power, you most likely need to call a professional repairman.