I had an HVAC guy come out and recharge my refrigerant, and the refrigerant line is "beer can cold" both outside and going into my attic unit. However, the air coming out of the vents is blowing low-to-mid 70s throughout the day, making it run basically all day long. What other things can I check myself before calling out an HVAC guy again?

Did he inspect and clean the coils, inside and out?

He showed me they were a little dirty and I cleaned them myself.

I admit I know almost zero about HVACs, but if the refrigerant line is cold, doesn't that mean the outside unit is working properly?

You cleaned the INSIDE ones yourself or the outside? Or both?

Further evidence I know nothing. I thought you meant the inside and outside of the condenser unit coils. I didn't know there are coils on the inside unit it my attic, too. He did not look at those.

DeLaHonta said:

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Further evidence I know nothing. I thought you meant the inside and outside of the condenser unit coils. I didn't know there are coils on the inside unit it my attic, too. He did not look at those.

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The one in your attic is the main thing doing the work to remove humidity. Hot air is blown across the cold coils to drop the water out.

If those inside coils up in your attic are really dirty it can't cool the air or remove humidity effectively. How long has the issue gone on?

This is starting to make a lot of sense. We had Reno work done, and there was dust everywhere. Mu contractor said he relaxed the filters in the attic, but it would make total sense for a decent amount to get past it and onto the inside coils. Is this a DIY-capable cleaning or should I call a pro?

Depends on your system. Some are more accessible than others. I think you need additional troubleshooting though. It might be those inside could. Could be something else entirely though. Could be compressor not function fully

How is the air flow from the vents? I had a similar problem. The builder's GC said our A/C "should" handle MERV11 filters, but I later switched to MERV8 and it was like night & day.

DeLaHonta said:

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I had an HVAC guy come out and recharge my refrigerant, and the refrigerant line is "beer can cold" both outside and going into my attic unit. However, the air coming out of the vents is blowing low-to-mid 70s throughout the day, making it run basically all day long. What other things can I check myself before calling out an HVAC guy again?

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Do you have any "dirt" on your vents on your registers?

Do you have easy access to your attic along with plenty of room to move around?

Torn/open ducts can lead to warmer air coming from the vents but there usually is signs of dirt/mold on the vents.

If you can walk/crawl around your attic then check your ductwork and any distribution boxes for obvious leaks.

I had a box feeding 2 bedrooms come open at an old house and after crawling around I was able to use some aluminum tape to seal it back up.

I had the ductwork replaced at my current place and had a distribution box that was saturated in water because it was torn open. The 3 vents it fed all showed signs of dirt/mold.

One other thing you "could" do if you are feeling adventurous would be to stick a instant read probe thermometer in your plenum right after the air handler to take a temp reading post evaporator. it will make a small hole and covering it with duct sealant should take care of it without any long-term issues.

Cold air coming out of the handler would lead to downstream problems. 70 degree air would mean your evaporator isn't doing it's job be it dirty or another problem.

I ended up buying an Anemometer to compare the flow and temp in each room trying to figure out what was going on.

Finding a good HVAC company can be a chore. If you are in Houston look up 88Agswin as he has an excellent reputation. I found one in Austin but he was in a bad car wreck and may have hung it up.

Good luck.