Air Conditioner Blowing Hot Air – Hello Richard, my air conditioner is blowing hot air today and I am wondering what’s going on with it. It is really mild weather here and still winter but the temperature here got above 80° F today and when I came home from work I decided to turn the AC on to cool the place down a bit. Cooler weather hits tonight when it’s going to be around 40° F according to the forecast. Is this something I need to worry about? It is uncomfortable in here right now but I can hold out until tonight. I’m just a little worried the next time I need the air conditioner? Should I call for service? Or maybe there is something I can fix?
Air Conditioner Blowing Hot Air - Basic Checks
There are several basic things you can check to try and fix the problem yourself. I have another page with a list of basics to check before calling for air conditioner service or repair. Perhaps that page will help you find the problem. Either way, I’ll discuss some specifics about your air conditioner blowing hot air here. Here is a list of basics you can check yourself and hopefully find the problem and make an easy fix for yourself so you can get comfortable now:
The first place to start is the thermostat. I know you’ve already checked it and probably stood there for a minute. Please double check this. I have shown up for a trouble call for air conditioners and other HVAC equipment and found the only problem was the thermostat setting. They had the thermostat set to heat when it should have been set to cooling or vice versa. It happens more than you think so please double check the thermostat and ensure you have it set properly. Make sure the thermostat is set to cool. Also, make sure the set point is turned down below the room temperature.
- Check the filter to make sure it is clean. A dirty, clogged air filter will cause problems with your HVAC system. If it is dirty then please change it. Also, make sure ALL the supply vents are open. Too many closed supply vents have the same effect as a dirty air filter. It reduces the air flow through the system and can have a detrimental impact on providing heating and cooling for your system. Make sure you have good air flow. A dirty air filter will reduce air flow and cause problems with the home ac unit. With any central AC system, good air flow is vital. A dirty air filter is bad.
- Now that you’ve checked the basics of all basics it’s time to move on to the bigger things. The thermostat is absolutely set for cooling and the indoor fan is running but warm is coming from the supply vents. I would go to the circuit breaker panel and check the circuit breakers for the condensing unit. This is the unit that is outside and it should be on a separate circuit unless you have a package unit system. Make sure the air conditioner condensing unit circuit breaker is not tripped. If the circuit breaker is tripped then its time to call an HVAC service and repair company to troubleshoot the air conditioner problem. A tripped circuit breaker means it is likely something serious and needs the attention of a trained technician for AC repair.
- Next, go outside where the air conditioner condensing unit is located and physically check it to make sure it is running. If it is not running check the disconnect. The disconnect for the condensing unit should be located within arms reach of the condensing unit. Depending on your system and the local code, the disconnect box could or could not be fused protected. If you pull the fuse block out and it has fuses then you need to check the fuses to make sure they have continuity. To do this you will need a multi-meter or an Ohm-meter. If you do not know what I talking about then your best bet would be to call for service. Hopefully, it is simply a blown fuse without any major faults in the condensing unit causing the fuse to blow. If not, you need AC repair. Time to call a pro.
Technical Problems that can lead to Air Conditioner Blowing Hot Air
There various problems that could lead to your air conditioner not functioning properly. These problems need the attention of a professional to make the repair and get your air conditioner cooling again. The following list is not comprehensive but it will give you an idea of the problems that may be found if you make the service call to have the air conditioner repaired. Hopefully, our list above has helped you correct the problem and you are good. Here are the possible problems that could cause your air conditioner to not function and blow hot air. These problems could also be applied to a heat pump in cooling or heating mode:
Home Air Conditioner Starts Cold then Blows Warm
- Loss of refrigerant charge which means you have a refrigerant leak that will require a refrigerant leak repair. If this is the case, look for ice on the refrigerant lines going to the condensing unit or the lines at the air handler coil. Note, this ice needs to be defrosted so make sure you turn the cooling mode off and allow the ice to melt. It will speed things up for the technician when they arrive. A leak repair can be simple or it can be intensive. It simply depends on where the refrigerant leak(s) is located. Low refrigerant will cause your air conditioner to blow hot air.
- A compressor issue such as compressor overheating or a bad start or run capacitor for the air conditioner compressor. These problems are the same as the refrigerant leak above. The problem could be fixed easily or it may require more intensive work to get the system working again.
- An electrical problem inside the unit such as (as noted above) a bad capacitor or a bad compressor contactor. Capacitor problems and compressor contactor problems can easily be repaired and most technicians carry the needed replacement parts on their van to make the repair.
- A plugged metering device or a malfunctioning metering device can cause the air conditioner or heat pump to stop cooling.
- A dirty evaporator coil will cause your AC to blow warm air. An air conditioner does not blow hot air. It is designed to blow cold air. Some of the problems listed above will cause your home AC to cool and the blow warm air later. The culprits on the list that will cause this “blowing cold at first then blow warm air” include a dirty evaporator coil. You can clean likely clean it yourself but I recommend letting a professional do it since it will likely require disassembly of components and them reassembly. In some cases, tools and materials will be required to clean the evaporator coil. Most maintenance plans or preventive maintenance service will include cleaning the evaporator coil and the condenser coil. A dirty condenser coil is next on our list.
- If your home air conditioner starts cold then gets warm it could be a dirty condenser coil. Instructions for cleaning a condenser coil are pretty basic. It does include a water hose and spraying water in a system that has high voltage so make sure you kill the power before doing it. Again, as stated above, maintenance plans typically handle these things. Get a maintenance plan or an air conditioner maintenance agreement and it should decrease occurrences of the air conditioner blowing hot air especially when you need it the most.
As stated above, some of these issues can be corrected easily and others will require major surgery. If major surgery is required I recommend you read the repair or replace page. Major surgery includes a very expensive repair so it will depend on the age of the unit whether I recommend you repair or replace.
Air Conditioner Blowing Hot Air - Basic Maintenance
I completely understand your predicament. Where I live, the temperature can be 80°F in the day time and then drop down to 35°F at night. This can happen in Spring, Winter, and Fall and sometimes you run the AC in the daytime and the heat at night. I always recommend regular maintenance checkups for your air conditioner. This ensures your system is operating properly and at peak performance. While these maintenance checkups do not guarantee your system will not break down it does help avoid potential problems in the future. I hope this helps you resolve your issue and you can finally find comfort with a properly working air conditioner.
Lastly, again, a maintenance agreement will give you air conditioning preventive maintenance that will nip a lot of these AC problems in the bud. Things like low refrigerant for a central AC and electrical problems can (and should) only be handled by a qualified tech. Most things in the outside ACs system will need a trained tech for any air conditioner repair anyhow. Get regular preventive maintenance and have comfort and peace of mind.
Air Conditioner Blowing Hot Air
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