So, this is really a loaded question because there are many things that can cause your system not to cool. So instead of boring you with all the potential issues that will lead you down a rabbit hole. I figured I would help with some basic things to check before calling and HVAC company.
The key thing to identify here is what type of system you have. The most common system used in Jacksonville Florida is a split system Heat Pump.
A Split System means that you have an indoor unit commonly referred to as an Air Handler or an Electric Furnace, this unit is usually located in a closet, garage, utility room and even your attic and in some rare cases under the home. The other system would be located outside – this system is commonly referred to as the condenser.
You might also have a Packaged unit – this means you have both your air handler and your condenser all in one package outside of the home somewhere. These are commonly see on manufactured homes, some historic homes that never had AC before and mobile homes.
There are other types of systems like actual gas furnaces and water to air source heat pumps. These are not as commonly used and for this FAQ I’ll just stick to the most commonly used equipment.
Now that we have that out of the way, lets dive into Split systems. Split systems should be running on a dedicated circuit coming from your breaker panel. So this means you should have 2 breakers in the panel that supply 240v to each component (the air handler and the condenser). In the panel each breaker should be labeled, The Air Handler breaker should be labeled HEAT or AHU sometimes FURN, the other breaker should be labeled AC or sometimes HP or CDU.
Now diagnostics time.
- Are both breakers in the “ON” position? If Yes Move to step 2 (A tripped breaker will appear in the middle or in some cases appear to be on, for a tripped breaker you MUST turn the breaker all the way off then back on again.) If No, Reset the breaker and see what happens. If the breaker trips immediately then you have a high voltage short somewhere in that circuit and you need to call an HVAC company to learn where that short is.” Buyer be where – untrustworthy technicians can try to persuade you into a new unit. You need to pay attention to what they are doing in this diagnostic, ask them to show you how they came up with this diagnostic, the experienced technician should be able to not only show this to you but explain it in an easy way to understand. If they cant explain it, they either don’t know or they are more concerned with making a commission for the sale of a new HVAC system.”
- Is there Power at the thermostat? If Yes Move to step 3. If your breakers are on then you should have power unless your thermostat requires batteries to operate. To eliminate this as a potential replace the batteries. The batteries should be located behind the face place. Each thermostat is different so be gentile when removing the face plate from the back plate.
- Have you checked your drain line? Your Air Handler should be equipped with a float switch and a clean out T, The float switch should be located next to the drain line, you should see a device that resembles a small cup with a black wire coming out of the top. This is the float switch, remove the top where the wire comes up and see if there is water in there, If there is its because your drain line is restricted or clogged. If No Move to next step. If yes, then you have a maintenance related issue on your hands and you’ll need to clean the drain line. Best way to do this is with a shop wet/dry Vacuum. See Drain line cleaning…
- Is there water in the drain pan? If No Move to next step. Some systems will have a secondary drain pan located under the air handler. This is common for air handlers that are located in the attic or on the second floor and in some cases suspended in the garage. This doesn’t mean that if your unit is not in this application that you don’t have one or even that you need one. Sometimes installers put them as a back up where they are not required by code and other times they don’t. If you have a Secondary Drain Pan you should also see another float switch this one will look a little different though. The easiest way to spot this switch is to locate the wires coming from the pan to the inside of the air handler. If there is water in the pan the float switch will be tripped preventing the system from flooding the home. Usually when water makes its way into the secondary drain pan there’s a reason. Here are a few reasons why water might be there.
- Frozen evaporator coil
- Faulty primary float switch or incorrectly wired
- Clogged primary drain line
- Dirty Air filter caused icing
- Cracked Primary Drain Pan
- Air Handler not level or pitched
- Dirty evaporator coil
- Is the indoor unit Running? If Yes the move to the next step. If not, then it’s recommended to call an HVAC professional. But you could attempt replacing your thermostat first to see if that fixes the problem. Remember follow all instructions and turn the power off before replacing the thermostat. Also you’ll need to configure the thermostat for a heat pump.
Is the outdoor unit Running? If the indoor unit is running that tells us that we have power and that the thermostat should be sending a signal outside to turn on. Some times the outdoor unit will appear to be running because the fan is spinning but the compressor may not be or vice versa. If its making noises its helpful to record a quick video of the system making those noises. Turn the AC breaker off for ½ hour or so then turn it back on (record this by video) see what happens. Weather the system comes back on or not you should still call a professional to solve this problem, there are to many potential thigs that would interrupt operation to name and most of it would require specific tools. The most common interruption for an outdoor unit not running is a failed Capacitor. This is a cheap part that can be purchased on line if your inclined to do so. The average capacitor replacement cost in the Jacksonville FL market ranges from $250-$800. Most AC companies wont install your part nor will they base their diagnostics off what you have done already. So if your inclined to do the work and diagnose it yourself, be prepared for that. You will need to collect info from your system so that you can buy the correct size capacitor. Then all you need to do is follow the schematics to ensure the capacitor gets wired up correctly. Be aware that improper wiring can and will cause permanent damage to your HVAC system and will VOID any warranties you may have with your installing contractor/builder and manufacture.