A/C went out, thoughts on the cause?

[TheZymurgist]

So yesterday, our A/C went out. The outside unit is running, and there's freon running through the pipes, but the attic unit isn't pushing any air. I can hear the fan start up, but only just barely, and it's not enough to feel anything coming from the registers. I tried shutting off the power supply for a little while to see if it would reset, but no luck. I also switched it to heat, and it's still the same issue. The furnace lights up, but no air runs through the unit.

Any thoughts on what this could be? I'm thinking the fan motor is going, but I'm not sure. The unit is 9 years old, which seems too early. I'm hoping I don't need to replace the unit...

 

[aiptasia]

Something with your attic unit.

 

[passedpawn]

The attic air handler contains coils that could be completely blocked. Obviously, they are not iced up if you tried the heat. So, maybe they are blocked by dust webs. Do you have filters on the returns in your house, or is there one large one in the air handler?

You should be able to open the side of the air handler and see the coils. Just take a look.

And sure, I guess it could be the fan motor.

 

[cfonnes]

Fan motor, or startup capacitor is bad.

 

[TheZymurgist]

The attic air handler contains coils that could be completely blocked. Obviously, they are not iced up if you tried the heat. So, maybe they are blocked by dust webs. Do you have filters on the returns in your house, or is there one large one in the air handler?

You should be able to open the side of the air handler and see the coils. Just take a look.

And sure, I guess it could be the fan motor.

I think we just have the one filter, and I checked it. It's pretty new, not more than a few months old, and still relatively clean. I did take off the upper and lower access panels, but didn't see the coils. However, if it was a blockage issue, would it be running just fine one day and completely stop the next? I think I would expect more of a gradual issue as the blockage built up. Plus, the fan is barely turning, almost enough to not even hear it.

 

[Wolfbayne]

Mine went out two days ago. Fan motor wasnt blowing. Repair guy said the internal coil filter thing (technical term) was clogged. Apparently the manufacturers put a filter on the inside that only repairment can get to. He took it out, cleaned it, and now the AC works better than it has before!

 

[TheZymurgist]

Mine went out two days ago. Fan motor wasnt blowing. Repair guy said the internal coil filter thing (technical term) was clogged. Apparently the manufacturers put a filter on the inside that only repairment can get to. He took it out, cleaned it, and now the AC works better than it has before!

Man, I hope that's the issue. My mind always goes to worst case scenario. I can just hear the repair man now: "You need to replace the entire unit, both inside and outside, including all of the duct work, or your house will EXPLODE!!!"

 

[Hello]

I think we just have the one filter, and I checked it. It's pretty new, not more than a few months old, and still relatively clean. I did take off the upper and lower access panels, but didn't see the coils. However, if it was a blockage issue, would it be running just fine one day and completely stop the next? I think I would expect more of a gradual issue as the blockage built up. Plus, the fan is barely turning, almost enough to not even hear it.

I had the same issue but my air handler is in the wrong place (go figure) as it is in the crawl space. My air handler for a/c unit (I have two) for the upstairs is is shot. It's a Carrier and evidently this brand is bullshat. They do not permit (or fit) any universal parts so since my fan motor is bad it is almost just as "cheap" to replace the entire air handler. The motor at cost is $600+ plus install and markup on the air handler motor itself. The recommendation I've been given is to get a new air handler (I'll be sold one at cost) and move away from Carrier.

My a/c freon is low but still over 50%. Because I have R22 freon (older type) it will be a couple hundred at least to refill. R22 isn't being reclaimed so there is no cost relief. My unit is 11 years old. The recommendation there is to get me a/c asap or at least get me an air handler before winter and work towards getting a new a/c. The other unit is older but supposedly has a newer (7 years) motor. I'm worried about that as well.

So your issues can be anything. What is the brand of air handler? If it is Carrier then read above again. That motor should be a couple hundred, not $600+ at cost to the a/c company. Talk about BS. The coils could be rusted if there is a lot of humidity up in that attic. My coils have some rust on them and I have to invest in a crawl space dehumidifier. I also have to cost out moving the air handler to the attic where it should be because it is working twice as hard to get air upstairs.

I ended up getting a window a/c unit and I moved my office downstairs until I save my pennies for a new air handler. Sorry to be Bad News Betty here. I certainly hope if it is a motor that is gone then you have anything but a Carrier unit.

Side note, nothing lasts as long as they used to. Any major appliance that we grew up seeing in our houses for 20+ years aren't made that way anymore. A/C units are seeing more like 10 years instead of 20.

 

[GilaMinumBeer]

Man, I hope that's the issue. My mind always goes to worst case scenario. I can just hear the repair man now: "You need to replace the entire unit, both inside and outside, including all of the duct work, or your house will EXPLODE!!!"

A/C system consists of 3 main parts.

Condensor (the outside bit), coil (a box with either a A shaped or Z shaped radiator coil inside), and the furnace/air handler. Between the condenser and coil are copper lines. wherever the copper line connect to the unit in the attic is where the coil is. You should also see a PVC pipe co0ming from it as well to drain off condensate.

It used to be commonplace to have a blank side to the coil box for access. Some units do not have this anymore. The coil can become matted with dust/detritus and eventually suffocates airflow. Best bet is to get a toothbrush and a shop vac. be very careful about applying any pressure to the coil as you do not want to bend any of the fins.

Often times, there is a air filter between the air handler and the return air. the return air is the duct that runs to the filter box for the house. the fileter in teh unit tends to be a very basic washable filter and is meant to further reduce the amount of dust taht collect inside the unit.

 

[TheZymurgist]

Thanks for the responses guys. I've sourced a couple repair people from friends, so I think I'll just have to end up calling one of them.

 

[DrunkleJon]

Also, in my eperience go with the cheaper air filters unless you or someone in your household have allergies and problems where you need a HEPA filter. This is because the tighter the filter the more air restriction you will get. The cheaper ones will still filter, though not as efficiently, but will allow far more airflow through and as a result stress your fan motor less. I just get the cheap ones and replace every/every other month or so.

 

[whoaru99]

^^^
Well, actually....the blower motor does more work when it's moving more air. So, put another way, the motor sees more load/stress with the filter that allows more air through it.

 

[whoaru99]

Obviously, they are not iced up if you tried the heat.

Not necessarily...I'm sort of assuming the heat was turned on and since it didn't work either it wasn't left to run very long.

If the evaporator is froze up (I've had this happen on my house AC when it was low on Freon) it takes a while to thaw out since no air can pass through it. I literally had no air coming out of the ducts even through the blower was running (that'd be a good sign too...blower runs but no air coming out).

 

[DrunkleJon]

^^^
Well, actually....the blower motor does more work when it's moving more air. So, put another way, the motor sees more load/stress with the filter that allows more air through it.

Turn on a fan with a pencil keeping it from turning, turn same model fan on unobstructed beside it. Let them both run. Pencil fan will fail first. Extreme comparison I know, but the added strain on the fan would shorten its life. Not to mention if air flow is restricted than the fan will need to run longer to heat/cool the house the same amount and as a result add wear to the fan motor.

 

[whoaru99]

Stopping the motor from turning is not anything at all like restricting the air available to the blower fan. Not even remotely close to the same situation.

About running longer, sure, I agree with that, but it would be running at less load so...

Note, what I say is for the centrifugal "squirrel cage" type of blower common in HVAC systems.

An axial flow type of fan, what might be called a propeller fan, doesn't exhibit this same characteristic. They tend to experience roughly the same or somewhat higher load with restricted flow.

 

[DrunkleJon]

Maybe I am thinking of the wrong sort of fan. I am no expert at HVAC systems, though the 25 year old heat pump in my house still running strong and only having been using the cheap filters verses my neighbors house built around the same time with a similar system having needed maintenance far sooner with the higher dollar ones does say a little for my 'theory'

 

[dkwolf]

Turn on a fan with a pencil keeping it from turning, turn same model fan on unobstructed beside it. Let them both run. Pencil fan will fail first. Extreme comparison I know, but the added strain on the fan would shorten its life. Not to mention if air flow is restricted than the fan will need to run longer to heat/cool the house the same amount and as a result add wear to the fan motor.

Very poor comparison. Because of the physics of an electric motor, when you "lock" the rotor (i.e. stick a pencil in the blades of a fan), the motor coils generate increasingly higher and higher currents in the windings, which will eventually either trip the circuit breaker, or ruin the motor windings. Much more the case in something like a 1/2 horse motor, but not good for a small fan motor either.

 

[TheZymurgist]

Anyways...

I have an A/C guy coming out tonight, so we'll see what the issue is.

 

[TheZymurgist]

Turns out it was a bad capacitor. $75, 10 minutes, and done.

 

[whoaru99]

cfonnes, post #4, for the win!

 

[LakesideBrewing]

Turns out it was a bad capacitor. $75, 10 minutes, and done.

Damn! I charged $225 for that. Good deal!

 

[TheZymurgist]

Damn! I charged $225 for that. Good deal!

Wait, you were charged that much, or that's how much you charge for the same work? Either way, that's a total rip off! It's a cheap part and easy to replace. If I had known how to identify it, I would have done it myself. Now that I do, that's what I'll be doing if it ever comes up again.

 

[mikescooling]

Wait, you were charged that much, or that's how much you charge for the same work? Either way, that's a total rip off! It's a cheap part and easy to replace. If I had known how to identify it, I would have done it myself. Now that I do, that's what I'll be doing if it ever comes up again.

I'm sure paying for the truck, gas, insurance, a livable wage and all the overhead of having a shop, is a rip off. To say nothing of customers who think they should get parts at cost and labor should be free. Next time your furnace or A/C breaks I think you should fix it your self.

 

[TheZymurgist]

I'm sure paying for the truck, gas, insurance, a livable wage and all the overhead of having a shop, is a rip off. To say nothing of customers who think they should get parts at cost and labor should be free. Next time your furnace or A/C breaks I think you should fix it your self.

Yeah, try to school the self-employed accountant on how much it costs to run a business. I've never heard of anyone charging that much to switch out a capacitor. I spoke to others that had the same work done and they were each under $100.

Assume the part, after mark up is $50. That would mean $175 for labor on a ten minute job. That doesn't seem high to you?

 

[FermentNEthinG]

Wait, you were charged that much, or that's how much you charge for the same work? Either way, that's a total rip off! It's a cheap part and easy to replace. If I had known how to identify it, I would have done it myself. Now that I do, that's what I'll be doing if it ever comes up again.

You better take a lesson on discharging capacitors if you think you are going to replace it yourself next time. You may get a life-ending jolt when you least expect it. Ohm's Law is a motherfu#&er!!!