Spring is here, summer is just around the corner, and that can only mean one crucial thing – it’s time to perform A/C maintenance! Here is a step-by-step guide to tuning up that air conditioning unit and making sure, when the Michigan summer heat arrives, you’ll be ready.
First, let’s clean and inspect the outdoor unit.
Clean any leaves and debris from inside the condensing unit and control box, making sure that the condenser fan spins freely and the blade is tight and in good condition.
Next, oil the motor (if it has oil ports) and inspect all the wiring connections for corrosion and ensure that the compressor terminals are tight and rust free. Make sure the contactor connections are tight and that the contacts are not pitted; if contacts are badly pitted, the contactor should be replaced as to not cause a voltage drop. Similarly, check the capacitor connections for corrosion and ensure the capacitor is not swelled up; replace it if it is.
Next, it’s important to clean the condenser coil with an approved coil cleaner. Many of the aluminum condenser coils such as Micro-Channel can be damaged by strong coil cleaners. A “shiny coil” means some of the aluminum has been removed and it is revealing new aluminum. That’s not good!
Replace or clean the air filter at the furnace, air handler or roof top unit (RTU).
Inspect the condition of the blower wheel as they will accumulate dirt and debris that can greatly affect the air flow. If the blower wheel is dirty, it should be removed and cleaned.
On belt drive equipment such as RTUs, inspect the belt and change it if it is worn or cracked. Check the pulley alignment with a straight edge and use a belt tensioning tool to ensure proper belt tension.
Inspect and grease the bearings if appropriate.
Drain and shut the water off to humidifiers and close the bypass duct to prevent air recirculation during the cooling season.
Inspect the evaporator coil inlet to ensure that it is clean. This is more difficult on A coils but they are also the most likely to get plugged!
Make sure the condensate line and pan are clear and test any condensate pumps by adding water.
Open any high wall return air registers. On ductless mini-splits check for an accumulation of dirt or mold near or on the plastic vents. The plastic parts may sweat due to the lower discharge temperatures, and can collect dirt or even start to grow mold. Special mini-split cleaning kits are available for cleaning when needed.
Let’s start up our A/C unit and check the operation.
Did the compressor and fan start? If not, we will need to trouble shoot.
Using a proper charging chart (Super heat for fixed metering device and Sub-cooling for TXV units) check the unit charge. Always refer to the manufacturer’s charging procedure when possible. “Beer Can Cold” is not a proper charging procedure!
If the unit is low on refrigerant we should first locate the leak and repair it.
Once the leak has been repaired, the filter drier should be replaced and proper evacuation procedures should be followed. Always use a micron gauge and change the vacuum pump oil before evacuation.
On packaged units including RTUs, weighing in the charge is always the best procedure. Ductless Mini-Splits are critically charged and must always have the charge weighed in.
Next, check the temperature drop across the evaporator coil. Measure the return air temperature as close to the blower as you can and check the discharge temperature as close to the evaporator outlet as possible. The difference on most systems should be between 16 and 20 degrees. If it is less than 16, we may be low on charge, or have other problems; if it is higher than 20, we may have airflow problems. Make sure you correct either condition. The temperature split on a ductless mini-split will be at least 30 degrees or higher.
Check all motor and compressor amp draws to ensure motors aren’t overloaded. If amp draws are too high find out why and correct the problem.
Follow these directions and you and your customers will be ready for the summer! Contact Dave Paruszkiewicz and the team at B-Y with any questions.
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