Troubleshooting AC | AC Blowing Warm Air

Troubleshooting AC | AC Blowing Warm Air

Troubleshooting AC | AC Blowing Warm Air

Home air conditioning systems contain a number of components dependent upon each other for the proper function of the unit. When one part malfunctions, the entire unit can fail to perform its job of maintaining your comfort. The AC blowing warm air is a common complaint. The following is a list of common causes of this problem and tips for troubleshooting the AC:

Refrigerant Leak

Refrigerant leaks are a common cause of the AC blowing warm air. Faulty service valves or wear and tear on the system due to age may be the cause of leaks. Leak repair and recharging the system should only be provided by a certified HVAC technician to ensure proper performance and the lifespan of the system.

Other problems that can be the cause of the AC blowing warm air include dirty coils, excessively dirty air filters, improper thermostat settings, tripped breakers and faulty components. 

Thermostat Settings

Homeowner’s will occasionally turn off the “cool” function to place the AC on the fan only. The fan may have been placed on manual to air the home, or to assist in pulling out the smoke from a burned dinner dish. The problem comes in when they fail to return the settings to the cool function and the fan from manual to automatic. 

Without the air conditioning operating in this situation, the system blows room temperature air throughout the home, and the homeowner may have forgotten to change the thermostat settings, or may even be unaware of the change if another family member provided it. 

This is the reason to first check the thermostat settings first, when the problem of the AC blowing warm air occurs. Ensure the fan is on “auto”, rather than “manual”, and that the setting is on “cool” rather than “off”. The solution to prevent this is to use a programmable thermostat, which allows temporary changes, and reverts to programmed changes on its own.

Furthermore, a thermostat will eventually wear out and perform poorly. A Cypress Heating and Air Conditioning professional can diagnose the cause of the AC blowing warm air, and provide the repair, or new installation that you need.

Tripped Breaker

A tripped breaker can shut off the central air conditioning units cooling function. Typically, when this occurs in the home’s electrical main and the AC will not do anything at all. 

However, when the system has breakers of its own incorporated inside the indoor blower, or an outdoor breaker box located near the condenser, a tripped breaker can prevent cooling while allowing the fan to continue to run. This is dependent upon the individual system, its components, and the system’s design. 

Ensure the AC breaker in your home’s electrical panel has not tripped. If so, turn it back on and check for cooling. Power surges or a problem within the system can cause this breaker to shut off. When the breaker continues to trip an electrical problem is present, or the breaker itself may be bad. Contact your HVAC technician for diagnosis and repair of your home’s air conditioning system.

If the breaker in the home’s electrical panel does not appear to be the problem, check the breakers in the cabinet where the blower is located if present, or outdoors in a breaker box located near the condenser. Otherwise, call for AC repair from a Cypress Heating and Air Conditioning professional.


An excessively dirty air filter can prevent the AC from drawing the air it requires. In some systems, when this occurs a breaker is tripped shutting off the power in order to protect the compressor, and depending upon the system features, the blower fan may continue to blow, resulting in the AC blowing warm air. Without the protective feature, a dirty filter can cause the system to overheat, and can cause compressor failure. For this reason, change the air filters as recommended without fail.

Dirty Coils

Over time the coils become soiled and the proper operation of the system declines, and can result in the AC blowing warm air. Annual maintenance on the system will provide inspection of all components including the coil. The technician will identify a dirty coil, and provide the necessary cleaning. Proper filter changes assist in preventing this, but eventually the coils are likely to need cleaning. Dirty coils can also cause the system to leak water out onto the floor, as can a stopped up drain line. 

A Broken Compressor

A failed compressor can cause the AC blowing warm air, and is a frequent reason for homeowner’s to opt for a new air conditioning installation

Cypress Heating and Air Conditioning’s experienced and certified technicians provide professional HVAC services . When your home’s AC is blowing warm air, and you were unable to resolve the issue with these tips for troubleshooting the AC, call our dedicated professionals for air conditioning repair. Our technicians provide professional quality repair and installation – guaranteed. We serve Katy, Plano and the surrounding areas, and are a member of the BBB with an A+ rating.