Simply divide the BTUs by 12,000 to calculate the tonnage of your unit. For example, if your air conditioner is 36,000 BTUs, you have a 3 ton unit. Some manufacturers bury tonnage or BTU information in their model numbers.
It is important to be aware and recognize the warning signs of low refrigerant to avoid further damage and costly repairs. If you notice weak airflow, inadequate cooling performance, warm air from vents, constant short-cycling, ice buildup, or unusual noises, take action.
First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.
There are a number of reasons why your air conditioner might be running but not cooling. It could be an issue with the thermostat, the compressor, or the evaporator coils. Or, it could simply be clogged with dust and debris, which is preventing it from working properly.
An AC leak will lead to warmer air from your vents over time. In most cases this can be fixed with a proven stop leak additive to seal up any leaks. When it's time for an AC recharge, turn to AutoZone.
Most ACs nowadays come shipped from the manufacturer with the exact amount of refrigerant that it will need for the duration of its life. So, unlike a car, your AC won't ever need to “fill up” on refrigerant unless something goes wrong with the system.
Steps to Check Refrigerant Levels
Attach the manifold gauge set to the service valves. Turn on the air conditioner and observe the pressure readings, which should be between 30-40 PSI for most systems (though some may require higher or lower pressures).
Your AC has limits, no matter its age, how well it was installed, its manufacturer, etc. As a rule of thumb, when it's 95 out, your AC can cool your house to approximately 70-80. Your air conditioner will be able to cool to about 15-25 degrees from the outside temperature.
It's cooler inside: One of the simplest ways to check if your air conditioning unit is cooling your home is to assess the indoor temperature. If it's cooler inside than outside, your air conditioning system is likely functioning correctly.
You can determine the efficiency of your AC by comparing the temperature of the air blowing out of the vent, to the temperature of the air being drawn into the system. Hold a digital thermometer up facing the air coming out of the vent. Wait until the thermometer has a steady read.
Another possible reason could be a dirty condenser coil. Located outside, the condenser coil dissipates heat from the refrigerant, not the cooled air. Dirt, leaves, or debris can block the coil, reducing its ability to transfer heat and thus making the AC work harder.
Go outside and see if the condenser is turned on.
While the condenser is on, place your hand about a foot above it. There should be air blowing out of it. If there is no air, the condenser is not working. If the air feels cool it means that your air conditioner is not removing any heat from inside of the home.
If your central AC is not blowing cold air, the refrigerant may be the problem. The unit could be running low and need additional refrigerant added. The most likely cause of this is a leak. A leak not only keeps the AC unit from cooling properly, but also it can cause other issues within the home.
Your AC might be stuck at 75 due to various reasons like clogged filters, refrigerant leaks, or the wrong unit size. It's best to have a professional diagnose and fix the issue.
Yes, you should turn off your AC if it's not cooling.
If you're low on refrigerant, you should notice that your air conditioner runs constantly, struggling to reach your temperature setting—or it may never reach it at all. On very hot days, you may even feel lukewarm air coming out your supply vents. Sure, summer electric bills are usually high.
Press the reset button. Most models require you to hold the button down for 3-5 seconds before releasing. Restore power to your AC. Restore power to the unit at the circuit breaker, and make sure the unit is set to “on” and your thermostat is set to “cool.”