It’s well recognized that your car or truck needs regular maintenance. You need to periodically change the oil and oil filter, change the air filter, and more in order to avoid breakdowns and get maximum life, as well as maximum miles per gallon, out of your vehicle.

HVAC contractors and technicians likewise emphasize to their residential customers that their HVAC system needs a regular tune-up to keep the unit up and running and provide optimum performance. With the air conditioning season approaching, now is the time to make the system checks and adjustments necessary to ensure a cool and comfortable home.

Matt Marsiglio, operations manager of Flame Heating, Cooling, Plumbing and Electrical, Warren, Mich., supplies his company’s 15 essentials of a residential HVAC tune-up.

1. Check operating pressures.

“If the operating pressures don’t fall into the proper superheat or subcool range, it could indicate you have a leak, it could indicate a restriction in airflow, either of which would cause the unit to not cool properly and run inefficiently,” said Marsiglio.

Besides these two problems, “you could have a problem with the compressor valves or a mechanical failure in the compressor.”

If the pressures are off, Marsiglio said, “The first thing you’re going to check is the air filter to make sure you don’t have a dirty filter. If suction pressure is low, that’s generally where we start. If it’s clean and the airflow is good, we’ll start looking at the charge in the system.”

2. Check air filter.

As Marsiglio noted, one of the first things Flame’s technicians will do is check the filter. “Probably the No. 1 service call for air conditioning season is a frozen coil due to a dirty filter,” he said.

Homeowners tend to have the impression they just changed the filter, no matter how long it’s been, said Marsiglio.

3. Check for leaks.

If the refrigerant pressures indicate it is necessary, the technician will then check for leaks. “There are a lot of leaking systems out there,” commented Marsiglio.

The best approach is to find the leak and repair it, or replace the system, he said. But sometimes cost considerations make use of a leak sealant an attractive alternative and Flame offers homeowners the option of applying a sealant.

When trying to find a leak, Marsiglio said, “you look at the brazed connections and mechanical connections before you look at the coils. If the leak is in the coil, it might be best to replace the system.”

4. Clean the condenser coil.

“We do a chemical cleaning with a biodegradable cleaner so it’s safe for plants, grass, and pets,” he said. “We also recommend that the homeowner hose off the coil at least once a month.”

As for the evaporator coil, he added, “We do inspect the evaporator coil to see if it’s plugged up. It’s not part of the standard inspection because accessing the evaporator coil in many cases requires additional labor. We have a no-rinse biodegradable cleaner for cleaning the evaporator coil.”

Usually an evaporator coil cleaning is required when the air filter has been neglected and hasn’t been changed.

“We also inspect the blower wheel,” said Marsiglio. “A very good indicator of how dirty the evaporator is going to be is how dirty the blower wheel is. If there’s a lot of dirt accumulated on the blower wheel, you can expect to see a plugged up evaporator coil.”

5. Oil motors.

“A lot of motors are non-serviceable; they don’t have oil ports,” remarked Marsiglio. But for motors that do have oil ports, they should be oiled.

Also, the technician should make sure that the oil ports are facing upward so no oil drains out.

6. Check evaporator coil for proper drainage.

“A plugged condensate drain is probably the No. 2 service call for the air conditioning season,” he related. “Standard procedure is to clean the evaporator condensate line on every inspection.”

7. Check the condensate pump.

“We verify operation of the pump. We also ask the homeowner to put a cap full of white vinegar in the pump monthly.” The vinegar helps keep the float and the pump line clean.

8. Check the amp draw of the unit.

“If the compressor is operating at a higher amp draw than normal, it could indicate there’s a weakness in the compressor, or you could have a restriction of airflow across the compressor through the condenser coil. It leads you into a couple possible directions,” Marsiglio said.

“We also check the amp draw of the condenser fan motor as well as the blower motor to make sure they’re all within range.”

Plus, he said, “We check the microfarad rating of the capacitors.”

In addition, the technician will check the voltage drop across the contactors, and make sure the contactors aren’t burnt or pitted. “Anything higher than a 10 percent voltage drop, we’ll recommend replacement.”

9. Check the belt on blower.

“We don’t see too many belt-driven blowers anymore. We’ve been seeing direct-drive for 20-plus years in our industry,” said Marsiglio.

“But we still have a few customers with belt-driven blowers, so we’ll check to make sure the belts have no cracks or are glazed over.”

10. Check if condensing unit is level.

“If a unit is a little off level, it’s no problem. But you see some that have a pretty good tilt to them. You do have oil in the compressor and you don’t want to have it all to one side or the other. So we try to ensure that the unit stays level.”

11. Check air temperature differential.

“We can check if we have the proper airflow by doing this,” Marsiglio said. “By taking the temperatures of the return and supply air, we can calculate if we’re in the proper cfm range. And it’s also a good way to verify your charge.”

12. Shut down the humidifier.

“If you don’t shut down the humidifier, it would reduce the amount of air delivered to the home.” This is because a bypass humidifier would create a bypass of air; so the tech makes sure to shut it down.

13. Check thermostat.

“We check to make sure the thermostat is operating properly,” said Marsiglio. “We check to make sure it’s secured to wall well.”

If an older customer still has a mercury thermostat, the tech will make sure it’s level and also that it’s calibrated properly. The tech will explain the benefits of upgrading to a digital thermostat. “But some customers just aren’t ready to do it yet.”

14. Check heat exchanger for carbon monoxide leaks.

This check is not just for the heating season. “Every time we touch a furnace, even if it’s a cooling season tune-up, we will inspect the heat exchanger. It’s a safety check for our customers. We want to inform the consumer if there’s a problem,” emphasized Marsiglio.

15. Change standard air filter.

If the customer has a service agreement with Flame, the tech will change the air filter. “Our standard filter for our customers is a 4-inch media filter.”

If the customer indicates concern about indoor air quality, it provides a segue to discuss home performance since Flame also provides home performance testing. The homeowner will be turned over to a comfort advisor for details.

Publication date: 4/8/2013