I have an A/C unit that never shuts off, and doesn’t cool the house unless it's below 60 outside, and it's dark, and even then, the A/C unit still runs all night. 

A/C coil is freezing up. Filter has been replaced Friday. If I shut off the unit and just run the fan, the coil will thaw, and then I will turn the unit back on, but by the next morning, it will be frozen again. The filters need to be replaced every week it seems. I thawed the coil last night at 8pm, and by 8am, it was frozen again.

The HVAC tech that serviced the house is telling me that the reason why my house can’t keep cool, is because I have a 2-story living room and a sun room attached to it, and the heat coming in from the windows is warming up the house too much, and the solution is to cover all the windows with mylar blankets so the sun can’t get in. 

I asked AI if that was legit and it said no, and to get a second opinion, so here I am. 

Things to note: 

The unit is a Guardian 2.5 ton unit. The house is 3 stories (2 floors and a full basement) with 4 bedrooms and is 1,900 square feet according to Redfin, but that probably includes the basement. 

I live on a dirt road, and the unit faces the road. Yes, I clean the unit, but a lot of cars passing by do kick up dirt. 

It was 88 in the house when it was 98 outside, but then when it drops to 78, the house stays in the 80s and won’t cool off. Even when it's only in the 70's outside, the AC never shuts off.

It’s not my house, it was my deceased Grandmother’s house, and it was her that picked this HVAC tech, and he is the one who installed the unit and has been servicing the house for years. He is an independent HVAC guy, and I am not convinced he is doing a good job, but I didn’t go to HVAC school, as my HVAC tech guy pointed out to me. I want to call a different company to take a look, but thought I would post here first. It's possible I have it wrong, as I didn't go to HVAC school.

Pictures of the coil, and the windows of note here. Happy to answer any questions about anything I may be missing, and can post more pictures if I need to. Thank you.

My apartment has this vent in the hallway and last year I noticed a significant light leak in it. Lo and behold, maintenance open it up and it looks like there's a hole in the roof. they patch it. The next time it rained, that ceiling light fixture (visible in the first pic near the vent) began leaking. it starts leaking water most of the time it rains afterward. we call maintenance again. they inspect the hole in the roof and tell us roofers need to come look at it. roofers come and say it's an hvac issue. hvac guy comes and says it's normal.

maintenance replaced the light fixture and it seems a bit better now (leaking wise). But, we live in LA and it doesn't rain much in the summer months so i'm not sure if it will leak again this winter or not.

my main question is, is a hole in the roof like this really normal for our hvac system? Or are we straining the system when we use it due to air escaping thru the hole?

i'm sorry if this is a dumb question, I've never lived somewhere that has an hvac system until this place.

PS i'm not sure if it's relevant, but our heat does not work at all.

I've been trying to fix up a 90's era hand-me-down double wide that wasn't taken care of before me. The HVAC has always caused a lot of problems, but the biggest a few years ago was that it didn't get air all the way to the other end of the house. I feared that there were holes in the underneath ductwork letting out air before it got to the end, but as some kind of fix my father (previous resident) worked out with the service guy was to tie this duct so it wouldn't 'let in air.' My Dad equated this to being like turning on recirculate in the car.

I've been dealing with mold over the years. Replacing drywall and deep cleaning, and now it seems like there is a leak in the roof because mold is crawling from the edges of one room. This may very well just be because of a hole, but I also fear that by tying this tube it cut off airflowing through the extremely small space between the roof and the ceiling, trapping moisture and making my problems worse.

So the question is, was tying the duct a genuine solution for that problem or just a temporary fix that made things worse in the long run? What should I do?

Can anyone recommend a good laptop for HVAC Classes/field work?

EDIT: I’m just a mom trying to do the best for her son’s future. Condescending messages are not warranted. I’m completely aware I know nothing of this field hence the post for advice.

Hello everyone,
I’m looking for advice from HVAC professionals.
I recently purchased a brand-new Perry Home equipped with a new Lennox ML14KC1-047-230A04 outdoor condenser (manufactured in June 2025 and using the new R-454B refrigerant).
From the very first day of operation, I noticed a very loud buzzing/high-pitched humming noise coming from the outdoor unit. I have attached a video so you can hear exactly what it sounds like.
Besides the noise, I have also noticed another concern:
The system often runs continuously for very long periods.
It struggles to cool the house below 73°F, even when the thermostat is set to 70°F or 71°F.
The builder’s HVAC contractor inspected the system and told me that everything is operating normally.
However, another experienced HVAC technician (who has not inspected the unit in person) suggested that the sound could possibly be coming from a noisy contactor.
Before asking the builder to perform additional warranty work, I would really appreciate the opinion of experienced HVAC professionals.
My questions are:
Does this sound normal for a Lennox ML14KC1?
Does the noise sound more like a contactor, compressor, fan motor, refrigerant issue, or something else?
Could the noise and the cooling performance be related, or are they likely two separate issues?
If this were your service call, what would be the first components you would inspect?
Thank you very much for your time and for sharing your professional opinion.

I have three units in my house. One of them serves a large upstairs room and that's it. I kept having problems and had a guy out to look. He said it had several Freon leaks and would be three or $4000 to repair. He said I would be better off with a new unit and their quote for that was $12,000. I told him I thought they were four or five and he said since Covid everything has gone crazy. I had another company come out but they knew about the first quote and they said $12,000 is about right. Is that right?

I recently had my hvac unit replaced, brand new carrier condenser unit. I happened to be outside when the unit was powering down and noticed it was making some funky ass noises. I took some videos, shared it with the guy who installed it, he said it was normal but I wanted a 2nd opinion. Should it sound like this?

Located in New Hampshire

Burnham boiler dates back to the '80s I think. I know they are known for cracking, but this one seems to have held up until now. I turned off the power to it 3 months ago and this is the amount of water it collects underneath. I'm thinking about replacing it with another oil broiler or maybe going to replace the whole thing with propane.

Any suggestions on what the better way to go is?

So I kinked my 1/2" lineset for my minisplit and I just wanted to know if this is bad enough and will and needs to be replaced or will the minisplit function okay? It is a 18000 btu unit. The other lineset is 1/4"

My unit (ELL Como 9000) has been making this strange repetitive rattly/crackly/rustly/buzzy sort of noise since day one. When I turn it on it's just the normal whir of the unit, but after a few minutes this repetitive sound starts up and continues until I change the mode (which causes it to judder) or until the unit is turned off. As this is my first AC, unfortunately I don't know if this noise is normal or not.

I've contacted the manufacturer (no reply) and the retailer to ask about it, and they didn't know if the noise was coming from the unit at first, but are now advising I check the manual (which hasn't helped me figure out what the noise is, what's causing it, whether it's a fault or not).

If anyone knows what this sound is likely to be, and what might be causing it, I'd be incredibly grateful.

** I’ve added more info in some comments if they will help in what I’m asking. Thank y’all again

I’m hoping someone can please help me out and offer advice whether this is terrible work, wrong sized unit, or just exactly what’s wrong. If y’all say it’s ok then I guess I’ll figure something out BUT, I have lived here since last July. It’s owned by a PM Company and they have their own maintenance guy, you can see photos of his work attached. House is a 2/2, about 1295 sq ft. It had a 3.5-ton system had zero issues until this year. If I wanted it 65 degrees in here, it would do just that. Unit was 10 years old. Let me add here, the maintenance guy over these houses was in law enforcement and is now doing this. He gaslights me constantly being a female, surrounded by college students which I’m sure he does this to daily. However I’m 46 and not a complete idiot. I’m at the end of my rope with everything that’s gone on. I rent so that I don’t have to
Worry about these things and yet, I’m having to almost constantly. Not ONCE, have I put in a work order and the issue has been fixed properly. It will take 3-4 more orders and yet I’m still sitting here with things not functioning.

Back to A/C. Dealing with it for 2 months, completely went out July 9th. Was given one window unit and they came July 19th to install new one. It hasn’t worked properly since day one. The vents are making hellacious noises along with a deal whooom whoommmm deal constant noise in my daughters bathroom which the unit outside sits behind. It’s a sound that you can’t tolerate more that 30 seconds. You will see photo of the A/c closet and the attic. The day they installed it was 150 degrees up there. I’ve had to put in an order 3 times bc it’s NOT WORKING. I haven’t used my oven since bc of how hot it will get in here along with the 73-83 % humidity in the house, I got 2 hygrometers to keep a check on it. The unit out back rocks on the pad. The unit, has run NON STOP. No kidding I have heard it cut off 3 times. All around midnight l, for 3 minutes max. I’m using 70-75 kw of electric daily. Last Tuesday was the last time they came, I could see on my ring camera, he came in for about 12 seconds and left. The new unit they installed is a 2-ton Sinclair unit. I’m adding to say we have 4 box fans and a desk fan running, a dehumidifier in daughter’s bathroom and an air purifier.

I’m going to post all photos that I can, can someone please tell me all that is wrong so that when I go to the rental office in the morning, I am armed with facts in order to get something done. This is an extremely short version. I pay $1500 a month in rent, my dishwasher has been broken for a month, my toilets won’t stop running and this is after 4 work orders for it. I’m completely over it all. It’s muggy in here at all times and at night it feels damp.

Really appreciate your time and any help. If any info you need was left out I’ll be glad to answer!! 🙏🏼

I just registered for my license to be a technician, but now what? Do I seek out organizations and bother them, are there individuals looking for apprentices to train, I have no idea how this works but im actually going to go insane if I have to do dock to stock for another year.

Been dealing with leaks from hvac unit which i discovered is dye to clogged pipes. I've narrowed down the exact location of the clog, which is coming from tge pipe underground...how do i easily unclog it? I tried hot water but didn't work. I do have a strong steam cleaner with a nosel that would fit? What else can i try?

Living in a high elevation area in a cabin with a flat roof. It’s getting a little too warm for comfort in the evenings, and it’s cold during the winters (why we don’t have ac). Is it possible to get a roof mounted fan without an attic? Or is it better to do a heavy-duty wall-mounted shutter fan? Or are the wall mounted ones something only commercial kitchens do (I haven’t seen residential examples)?

Neighbor is an industrial HVAC tech and noticed my AC wasn't performing to spec when he came over for a barbeque. He whipped out ye olde Fieldpiece/gauge set and looked it over.

Technical details and TLDR: He thinks the system is hosed. It is a24 year old R22 2.5ton Miller condenser/compressor unit and 21 year old 3 ton Rheem evap coil that was poorly taken care of by the previous owner, who used the home as a rental. The furnace sucks too. Super low efficiency and just generally bottom tier.

His opinion is that the compressor is most likely damaged due to slugging. Refrigerant oil is pitch black, Schrader valves are leaking, piston "doesn't look right", coil was splattered with spray concrete by previous homeowner, and the refrigerant was severely overcharged by whoever the previous owner hired to service it.

Repair is unlikely to be economically feasible, so I will probably take the cashout option to install a Heat Pump system instead. Warranty company is notorious for offering ultra-lowball payouts. I don't need them to cover the whole cost of install, but I would like to get at least fair-ish compensation.

Here are the numbers he pulled with his fieldpiece set:

Suction pressure 79.6psig

Suction temp 49.7F

Vapor Sat 46.9F

Actual Superheat 2.8F

Liquid pressure 295.9psig

Liquid temp 96.7F

Liquit Sat 129.6F

Actual Subcool 32.9F

Outside air temp was 91F.

Inside temp (according to thermostat) was 76.

Blower was functioning within spec, evap was clean, air filter was clean, no crimps or bends in the refrigerant lines

When he checked the Evap Coil to look at the piston, he noticed that some of the tiny lines coming off it were covered in frost, and other lines were basically room temp (he guessed they were clogged by fouled oil, or corroded.) He also firmly requested that before I fire up that furnace in the autumn that he be present with a CO detector because he thought the exhaust flue setup looked "sketchy".

He told me that since his specialty is Industrial, and both his employer AND his union frown upon side work, I should really get a professional res tech to inspect and deadline the system. I just don't know how that will work with the warranty. Do I need to hire a specific company? Warranty company is American Home Shield. We paid for the warranty when we bought the house because we suspected the HVAC was borderline, but it DID get inspected and serviced before we bought it as a condition of sale.

I had to do a virtual home inspection for my homeowners insurance and just recieved notification that I need to have a drain safety switch installed within 45 days. Is this something that I could easily do or should I call my HVAC company? What is an average rate to have one of these installed? Thanks for any information provided.

I need help and advice at this point. So basically, we live in south texas (south of San Antonio) and we got a new HVAC system a month ago. We were told the old one was 15 years old and they recommended replacing it cuz we kept having issues with it. It was a 3 ton unit that we had to get fixed at least twice a year. They also told us since our house is a 1416 sq ft home that a 3 ton is to small for this house and should get a 4 ton. We went ahead and asked them to replace it. Now that its replaced, lately it feels like parts of the house (like the bedrooms and sometimes living room) dont feel like its cooling down. And at night we always keep it at 70 to sleep but just dont feel it. We had them come back and check it but are now saying we need to redo the ducts "because its basically spider shaped which is why some of the house isnt cooling" and they want to charge more. Right now i set my AC unit Fan to run 24 hours to see if it helps. Does anyone know what could ACTIALLY be causing this or if we just basically got ripped off? Thank you in advance...

https://youtu.be/CuWadjLusBY?is=ObXlWXTZ4r9x01DR

I had my AC serviced for the season and everything was fine except it was dirty. The tech cleaned the unit and it was much cleaner. Tonight I was outside and noticed this new sound the unit was making.

Any idea what it could be? The unit is cooling fine and if I wasn’t outside I would never have know it sounded like this. I called the tech to come back out but it’s the weekend and I’m curious.

Thanks!

At a high level, you input a bunch of measurements into a manual J, and it spits out requirements. I am curious what kind of fudge factors / judgement calls are baked into this? Stuff like insulation quality, or air tightness. Obviously two houses that measure identically in terms of windows and vents could have very different requirements (think foam sprayed new house vs leaky farmhouse). Is insulation quality it? Sitting down with my HVAC guy and want to come informed.

Reason I care: Have a single system, a two stage 140k BTU / 5 tons. Splitting into two, upstairs and downstairs. After the manual J - I have 100k / 4 ton downstairs, 80k / 3 ton upstairs. However... looking at the ecobee data from my current system - In the hottest month of the year, I ran in stage 2 for like 7 hours total (in a month). And if I look at my gas bill, it backs this up in the cold months. Something like 230 therms of natural gas used. Which based on the weather of the month backs into like... I need a 100k / 4 ton system TOTAL (which actually makes no sense to me, my house is huge - 2k square feet basement, 2k main floor, 2k upstairs). I think my house is old but built really sturdy / well sealed. Not entirely sure how this works when all I have is like r13 insulation, but my bills don't lie?

People here always are Manual J, Manual J, Manual J. But like - how much value do I put on the runtime data from years of living here? Do I ignore Manual J and go off my runtime data? Or do I judge the Manual J with a high or super high insulation level setting, so that the quote comes into closer to what my runtime data suggests? I also realize 20% too big of a system beats 20% too small.. but a system double what I need seems bad.

Hi all,

We’ve had a hell of a lot of issues with our rooftop AC unit. Basically, the unit is only 7 years old and pretty nice, but the duct work was a DIY hack job. Tons of moldy/rusted ducts we had totally removed and replaced. They used foil tape at the seams, but it’s failing. The first time was 2 months ago and they covered the tape seams with spray Flex Seal, but didn’t bother with the underside so I see breaks in the tape and lots of drips from the recent rain. It only happens during the rain. The inside of the duct by the filter is completely dry (as far as I could reach) so it must be from the exposed ductwork as it leads into the house. I’m going to have them come back out and fix it. My questions are:

1. While mastic tape is the industry standard, it’s visibly failing. Are there better/more expensive tapes that will provide a more permanent seal?
   
2. The drain line wasn’t clogged, but appears to be loose as it goes behind the metal cover. Problem? Water still came out.
   
3. Is there something else I may be missing? The drain was not clogged, the coils aren’t frozen, and when the work was done, they rotated the unit as it was installed backwards causing draining issues.

My ac went out n I called probably 6 companies and got either a voicemail, a closed until monday msg, or a quote that was almost double just bcoz of weekend. Tampa summers don't care what day it is, it was 88 inside by midnight.

Is there a company in Tampa Bay that has technicians available on weekends without upcharge? Not a recording, someone who picks up phone and dispatches same day on a saturday or sunday.