Had our AC shut off a few weeks ago, needed Freon, guy added 6 lbs. 10 days later, it shut off again. I had another guy come out and he said it was low on Freon and the thermal switch had flipped from overheating. He added 2 more lbs.

First guy came out yesterday to look for a leak but couldn't find one. Recommends replacing the unit and coils as the current unit is 9 years old. Thoughts?

BR 12 said:

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First guy came out yesterday to look for a leak but couldn't find one.

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Man, how long did he look and what instruments did he use? I would think a leak that size could be found either with UV dye or with an electronic detector.

I've even had coil leaks where I could hear it leaking, after eliminating all competing noise sources.

Is it a heat pump? I ask because with the high pressures 410A runs it really does a number on a thin-walled indoor coil when in heat pump mode.

Are you using the same HVAC company? IMO, HVAC companies can be very shady and just want to replace a unit and not do repairs. Make sure you get a 2nd and 3rd opinion if you hear that a unit replacement is recommended by the 1st.

Thanks so much, I'm in Dallas though. I'll probably have the other company come and check it out before pulling the trigger on a new system.

9 years isn't very old.

Think he just used an electronic sensor. And no, not a heat pump.

Call Mechanical Air Design out of Carrollton and ask for Robert. He's their lead tech. Great company, very fair, and Robert will shoot you straight.

Reminds me of one new house build awhile back
Owner hired the cheapest homebuilder that would drive an hour to the build site farm.
Although the very best HVAC in town installed the system, after a few years a leak such as yours began and got worse.
Owner blamed HVAC, got another HVAC from his farm area to inspect, only to not find the leak and that farm HVAC guy was all BS.

Leak found!
Gun nail through wall sheathing pierced a ref.line
but it didn't leak until much later ... some guessing that the fluid motion eventually worked that nail point loose.

There was a lot of gypbd removed, about chest high, bigger than a basketball diameter.

Ergo, why sign up for replacements not yet proven to show a leak, only b/c these ARE the prime suspects most times?

That's what he kept saying, 95% of the time the leak is in the coils, just can't find it.

Going to have a few more guys come out to see if they can find the leak. Or should I hold off for a few weeks to see if the Freon levels have dropped to confirm a leak?

BR 12 said:

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guy added 6 lbs. 10 days later, it shut off again. I had another guy come out and he said it was low on Freon and the thermal switch had flipped from overheating. He added 2 more lbs.

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Enough proof of a leak, be it in walls, coils, switch/other.

Find the leak = job#1

It sounds like you're dealing with ongoing issues. Given the age of the unit and repeated Freon loss, it might be wise to consider replacing it, especially if repairs are costly. For now, I'd recommend getting a thorough inspection before deciding to replace the whole system. I had a good experience with the guys from https://alphamechanicals.com/blog/how-to-detect-hvac-refrigerant-leak/ who did a HVAC leak repair.

Had company #2 out today and he found the leak in the coils within the outside unit. Quoted $4200 to replace those coils with a one year warranty or $4650 to replace the whole unit with a 10-year warranty. Seems an easy decision.

I had the same issue with our upstairs unit in February except the leak was in the inside coil. Also super expensive to replace the coil so just bought a new unit.

Do you guys service Sugar Land? I'm looking for someone to replace my coil. I work with a guy who does A/C repairs on the side. I got the error code 79 (low refrigerant), he came out and added refrigerant in July (right after the hurricane), and now today the error code is back (and we definitely noticed it was not cooling upstairs). We were trying to wait until cooler weather to replace the coil, but it doesn't look like that will be happening. He doesn't have any availability to do the repair at the moment, so I'm looking for someone or a recommendation for the sugar land area.

Yes we will take care of you. Please call the office at 346-482-2691 and Anna will get you scheduled

I really appreciate it! Thank you!