House AC died need some info

[sledge]

Air handler is blowing air, nothing but a hum from the outside unit (compressor?) It's a Rheem 10 SEER built 10/02 so I know it's ripe for replacement. But I'm hoping I can get away with a band-aid until my old man (30yrs HVAC) gets back from his cruise and hooks me up.

I have no gauges and only a simple multi-meter, but if there's something I can check (or smack with a wrench) before I call out the AC techs, let me know.

[Chris]

Is the evaporator coil frosting up? Are you getting air flow out of your registers?

If you're not getting flow, the freon is probably low. Otherwise, replace the motor capacitor.

[JupiterSunsation]

I replaced one late last year. I can't help you with the diagnosis but can tell you to get with a company that does rebates with your local power company/Obama. The SEER rating is somewhat misleading (as in as the unit ages the SEER value actually drops). But when buying new with an authorized rebate installer the rebates can really add up.

I got pitched everything from Trane 13 SEER to the highest level XYZ brand SEER available. The deal I ended up going with was the longest warranty with the highest rebate and the best SEER rating (most bang for the buck). Funny thing was it was almost like mattress shopping since no two companies pitched the same unit so it was tough to decipher what was the best price due to the variation in units.

[Boss460]

Air handler is blowing air, nothing but a hum from the outside unit (compressor?) It's a Rheem 10 SEER built 10/02 so I know it's ripe for replacement. But I'm hoping I can get away with a band-aid until my old man (30yrs HVAC) gets back from his cruise and hooks me up.

I have no gauges and only a simple multi-meter, but if there's something I can check (or smack with a wrench) before I call out the AC techs, let me know.

Refrigeration manufacturer here. You say outside unit is humming. You also didn't say anything about the fan (on the outside unit) not running so I'm assuming it is. The noise from the compressor should be easily distinguished from the noise of the fan.

[cigdaze]

Drain pan full? Line clogged? Float switch stuck?

I had the same symptoms last spring. My moisture collector drain pipe was clogged and the pan filled up, float switch killed the system. It still blew air but the rest of the system did not operate.

[sledge]

"outside humming" as in electric motor getting juice but not turning. Fan not turning.

Mom staying with me, she cranked it down to 73 last couple of nights and the d@mn thing runs non-stop (until my frozen @ss gets up and turns the temp up). I wouldn't doubt there was a frozen evap at some point.

Yeah Nick, I had that happen once before so already checked that; nice and dry.

Not looking forward to having to "shop" the AC stuff if my dad can't help out. Of all the mechanical stuff I've learned from him, I've only recently started messing with auto AC. Between this and plumbing, I need to learn how to solder/braze some copper pipe already.

[sledge]

Jup, tell me more of what you ended up with. I'm down in Broward so I'm a FPL slave like you.

[Boss460]

"outside humming" as in electric motor getting juice but not turning. Fan not turning.

Mom staying with me, she cranked it down to 73 last couple of nights and the d@mn thing runs non-stop (until my frozen @ss gets up and turns the temp up). I wouldn't doubt there was a frozen evap at some point.

Yeah Nick, I had that happen once before so already checked that; nice and dry.

Not looking forward to having to "shop" the AC stuff if my dad can't help out. Of all the mechanical stuff I've learned from him, I've only recently started messing with auto AC. Between this and plumbing, I need to learn how to solder/braze some copper pipe already.

Without the fan turning, the compressor would be unable to stay running (if that's what's humming). Does the hum come and go after a few minutes? The compressor would overheat and keep kicking itself off on high pressure for a few minutes. If this is the case replace fan motor. Based on what you've told me it's nothing serious and shouldn't need to replace the entire unit.

[Chris]

If it's humming outside the compressor may be running. Let it sit for a while then have someone kick it on while you're down the basement. You'll hear fluid running in the lines. You should get a little cooling with the fan not running, but not much.

There are breakers in the cabinet- if you get restrictions on airflow they'll pop. My buddy has two units below his office window. He's got bird feeders on the sills. He called me last week- no air, I went and looked- they were full of sunflower seed shells. Cleaned them out, popped the breakers and it runs fine.

[Boss460]

By the way since the fan is on outside of the unit you should be able to put your ear on the motor itself to see if the humming is coming from it. If it is NOT coming from the fan motor then you definitely have a bad fan motor and that's all. The only other thing on it that could hum is the compressor and means it's fine.

[JupiterSunsation]

Jup, tell me more of what you ended up with. I'm down in Broward so I'm a FPL slave like you.

FPL rebate, govt. tax credit and Rheem rebate. Changed the whole unit inside and out (power bill dropped $75 a month as well). The original unit was 2001 model, house built in 01. This was my upstairs unit (3 ton), downstairs is still a 2001 model (5 ton).

Unit was about $5700, after rebates/tax credit I laid out $2700 total out of pocket. I will PM you my guy's info. He actually is a neighbor and I liked his price/personality better than the other 3 guys (one of which was my a/c guy for 3-4 years). He also changed a whole unit out for a buddy of mine in Lake Worth last year as well. He has 5-6 trucks on the road and would easily do a job in Broward.

[sledge]

I'm no humming expert , but I'm gonna say it's constant? Is it the compressor motor that's typically two-stage? It might be a louder hum initially then less humming.

Would there be a breaker on the outside unit? I would figure if it's humming, it's getting juice. Breaker on air handler isn't tripped, still blowing air.

[Boss460]

It might be a louder hum initially then less humming.

You just described what a compressor sounds like. Replace your fan motor and voila fixed.

[sledge]

Ooof, $5700 for a 3-ton? I'm either 3.5T or 4.0T (hating these vaulted ceilings). At least the after-tax OOP isn't so bad.

[JupiterSunsation]

Try to spin the fan with a stick (anything but your fingers) it may have a bad run/start capacitor. The fan may continue spinning once you give it a push off......

[sledge]

So can a reasonably mechanically inclined dude replace a fan motor himself? What else can I do to double check before I tear it all apart? Ballpark cost for a motor?

I just scheduled a service call for between 5-7pm. Race is on to see if I can fix it before they get here.

[JupiterSunsation]

Ooof, $5700 for a 3-ton? I'm either 3.5T or 4.0T (hating these vaulted ceilings). At least the after-tax OOP isn't so bad.

The net number was fine with me and if I had the money I would easily change out the 5 ton downstairs unit. Just paid the property tax bill (8K) and insurance ($5600) so it drained my "household" account!

I suspect this summer I will change it but for now it is blowing cold!

[Sunsation96]

Could be a few things that will cause the "humming"

1. The rheems use a dual capicitor for both the fan and the compressor. The capicitor could be bad see if the top of it is out of shape. It will look like the capicitor exploded from the inside out. A good multi meter will check capicitors.

2. The "humming" could also be caused by your contactor pulling in but having no main 220v power at the condensor check for 220 on L1 and L2.

3. The condensor fan could be frozen causing the internal saftey to shut off on the compressor. See if the fan will turn with a screw driver with the power off.

Call me if you have any question 586-557-2629 Jonathan

[Boss460]

So can a reasonably mechanically inclined dude replace a fan motor himself? What else can I do to double check before I tear it all apart? Ballpark cost for a motor?

I just scheduled a service call for between 5-7pm. Race is on to see if I can fix it before they get here.

Sounds like fun. Let's do it! He is right it could be the motor start cap. Try spinning it first. It'd be cheaper for sure. Motor itself (been a while but if I had to guess) around $100. It's attached to the grating on the unit. Should be bolts holding grating to the unit. Once those are unbolted just lift it up, disconnect wires and take it to a supply house. They can even check the motor to verify it's death. Then it's just a matter of reconnecting wires and rebolting.

[Sunsation96]

Dude I can own a Mystic if I work down by you guy's prices are crazy I am packing right now see you in a few day's