Our industry has a dark secret and it’s time we talk about it. Most techs and installers use their refrigerant gauges as the first go-to tool when on a no-cooling call. Many even put the gauges on first when they are doing routine maintenance. This is the worst thing you can do on maintenance, service, and even installation calls.
There is no way to verify if a charge is correct without knowing one critical piece of information: Airflow at the indoor evaporator coil. Unless techs first verify airflow, they may think the charge is off.
Closed Systems Don’t Consume Refrigerant
I can’t tell you how many times I’ve heard a homeowner say, “They topped off my Freon.” Anyone in our industry with even the most basic knowledge should know these are sealed systems, and refrigerant doesn’t get “used up” like oil in a gas engine. If you have anyone on your team saying that, tell them to stop immediately!
Compressors Don’t Die, They Are Murdered
The top cause of compressor failures is not defects. Compressors fail based on how equipment is installed or serviced. Charging without knowing airflow can cause many issues, including coils freezing and compressors slugging due to liquid flood back.
Occasionally a bad thermal expansion valve (TXV) can cause failures as well, but the top issue is inadequate airflow. There is no earthly reason to gauge-up on a system before checking airflow. Measuring evaporator temperature change (ΔT) is not the right way to verify airflow.
Another important reason to not disturb the refrigerant system is doing so can cause problems including leaks, introducing non-condensables, and cross contamination. Also, every time you “tap” in you are reducing the charge because of what remains in the hoses.
If you don’t know actual airflow across the coil, and touch the refrigerant side, you are likely guilty of malpractice. It’s like a surgeon not getting vital health information – or not washing his or her hands – before cutting into you.
The Right Way
Let’s look at the two correct workflows for service and maintenance:
1. Maintenance. When performing maintenance, leave your gauges in the truck! After your cleaning and inspections, measure Total External Static Pressure (TESP) at the correct equipment test points, then measure ΔT across the evaporator coil.
If you’re not getting the right temperature drop across the coil and static pressure is off more than 10%, alert your customer and ask permission to dig deeper at your regular service rate. If you don’t have diagnostic capabilities, bring in a tech to do more testing and offer solutions.
2. Service. If the issue is a no-cooling or poor cooling problem, verify airflow first. If your ΔT is off and airflow is low, offer to test further. Once you have correct airflow, check temperatures at the coil. If good, don’t touch the refrigerant side. If not cooling properly, then check and adjust charge if needed.
Follow these two simple workflows and you’ll have happier customers. You’ll also generate great leads for equipment replacement, air distribution upgrades, and renovations. By integrating this approach into your culture you’ll see customer satisfaction and referrals soar. You’ll also have happier technicians and a bigger bottom line!