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Who's Central A/C knowledgeable?

Posted By: MONC

Who's Central A/C knowledgeable? - 07/17/19 04:35 PM

So we had Central A/C ( with heat pump ) installed about a year and a half ago.
Last season A/C worked fine .
This season, the A/C runs fine during the day, but in the late evening , the outside compressor is on, and the blower fan is on in the house, but I get barely any air flow.
I have been turning it completely off late at night ( concerned of burning something out ) .
When I turn it back on the next day it blows cold with good air flow until late evening again .

I am thinking the blower motor is fatigued or something.
The belt is brand new, there is no overheating / burning smells , so I don't think it is overheating .

Any ideas, or suggestions ?

Thanks in advance !
Posted By: Orange_Crush

Re: Who's Central A/C knowledgeable? - 07/17/19 04:39 PM

Originally Posted by MONC
So we had Central A/C ( with heat pump ) installed about a year and a half ago.
Last season A/C worked fine .
This season, the A/C runs fine during the day, but in the late evening , the outside compressor is on, and the blower fan is on in the house, but I get barely any air flow.
I have been turning it completely off late at night ( concerned of burning something out ) .
When I turn it back on the next day it blows cold with good air flow until late evening again .

I am thinking the blower motor is fatigued or something.
The belt is brand new, there is no overheating / burning smells , so I don't think it is overheating .

Any ideas, or suggestions ?

Thanks in advance !


Does your AC have a HEPA filter? Check the filter and replace and see if that helps.

The other issue that you might be having is that you might have involuntarily signed up for your power company's energy saving program where they reduce power to your AC system during certain hours. That happened to me at one point.

Check and see if there's some kind of module installed on your outside unit's power supply with your power company's name on it.
Posted By: 4406bbl

Re: Who's Central A/C knowledgeable? - 07/17/19 04:56 PM

If it blows fine all day, but not in the evening and the compressor is running, I would say it is low on freon and the coil is freezing up, blocking air flow.
Posted By: rapom

Re: Who's Central A/C knowledgeable? - 07/17/19 05:31 PM

Coil freezing up sounds like the best answer. It has a chance to melt during the night which is why your good the next morning.
Posted By: Orange_Crush

Re: Who's Central A/C knowledgeable? - 07/17/19 05:33 PM

Originally Posted by 4406bbl
If it blows fine all day, but not in the evening and the compressor is running, I would say it is low on freon and the coil is freezing up, blocking air flow.


I thought about that, but it if a 1.5 year old system is low on freon, He may have bigger problems.
Posted By: RobG

Re: Who's Central A/C knowledgeable? - 07/17/19 06:15 PM


Idiots where my sister lives were sucking freon/refrigerant from peoples AC units to get high. Almost everyone on here street were hit by these punks.
Posted By: Tom_440

Re: Who's Central A/C knowledgeable? - 07/17/19 06:24 PM

Originally Posted by RobG

Idiots where my sister lives were sucking freon/refrigerant from peoples AC units to get high. Almost everyone on here street were hit by these punks.


I learned something new today. Thank-you.
This must be the single benefit to having my AC units up high on my second story roof.
Posted By: 318 Stroker

Re: Who's Central A/C knowledgeable? - 07/17/19 06:41 PM

Originally Posted by Tom_440
Originally Posted by RobG

Idiots where my sister lives were sucking freon/refrigerant from peoples AC units to get high. Almost everyone on here street were hit by these punks.


I learned something new today. Thank-you.
This must be the single benefit to having my AC units up high on my second story roof.


May not be safe there. They'll send drones to siphon it off... laugh2
Posted By: BB14404SPD

Re: Who's Central A/C knowledgeable? - 07/17/19 08:16 PM

Go where the blower unit is and check for this. Insulating mats are glued to the sides and top of blower unit to help with noise and keep hot in winter.. They are not glued very well. They fall and restrict airflow. The coil freezes and no cold air. Also make sure the drain line is cleared. Mine was a trane. Also get the cheapest filter you can buy and change them monthly. Expensive filters do not let enough air in and clog up quick.
Posted By: RWG75

Re: Who's Central A/C knowledgeable? - 07/18/19 12:17 PM

Pop the service cover off the outside unit. It's usually about 4 sheet metal screws at the corner where the wiring and plumbing enters. Look for one or more LEDs on the circuit board that might be flashing. The inside of the cover should have a wiring diagram and a table for decoding the flashes in to actual errors. Generally verify that the outside unit (compressor and fan) are operating correctly when the problem happens. Last time I had mine replaced, it acted up a few times during the first year until I found and fixed a couple of shaky electrical connections from the install.

Getting inside the the inside unit (evaporator and circulation fan) is less easy. The obvious service panel mostly gets you to the control relays and the emergency heater coils. Look for a less obvious panel on a different side of the unit until you can lay hands on the actual fan, squirrel cage, coils, drains, etc. Stare and compare at what's going on day time vs night time.
Posted By: Sunroofcuda

Re: Who's Central A/C knowledgeable? - 07/18/19 05:15 PM

Originally Posted by MONC
So we had Central A/C ( with heat pump ) installed about a year and a half ago.
Last season A/C worked fine .
This season, the A/C runs fine during the day, but in the late evening , the outside compressor is on, and the blower fan is on in the house, but I get barely any air flow.
I have been turning it completely off late at night ( concerned of burning something out ) .
When I turn it back on the next day it blows cold with good air flow until late evening again .

I am thinking the blower motor is fatigued or something.
The belt is brand new, there is no overheating / burning smells , so I don't think it is overheating .

Any ideas, or suggestions ?

Thanks in advance !


Trust me, it is an owl - they are nocturnal. One is messing with you - may be sucking refrigerant to get high while you are sleeping - just like the aforementioned punks.
Posted By: MONC

Re: Who's Central A/C knowledgeable? - 07/18/19 06:26 PM

Thanks for all the replies and suggestions.


I did think it might be a filter issue, so I replaced it with a mid-quality filter, and it did not help.
I will check to see if I have some kind of module from the power company on there, but don't think so.

I will check drainage hose.
Was going to check to see if coil was freezing up last night, but the dang thing ran fine all day and night long ! Why? I don't know .

I would think if some kind of insulating mat came unglued it would block the flow entirely, not just during the evening, but will see if I can get in there to check.
My inside unit is older , so new fancy electronics in there.
I will check out side service panel and see if there's any LEDs or other blinking lights for troubleshooting purposes.

Maybe I can get some pics on here for reference.

I do not think idiots or owls are sucking my freon out, people and animals not that sophisticated in these parts, lol .
Posted By: Mastershake340

Re: Who's Central A/C knowledgeable? - 07/18/19 08:59 PM

In Chicago people are stealing AC's, and there are security cages available on the market to enclose them to keep them safe!
https://wgntv.com/2019/07/17/several-central-air-conditioning-units-stolen/
Posted By: BB14404SPD

Re: Who's Central A/C knowledgeable? - 07/19/19 01:58 AM

If you look in the blower unit it could partial of fully block. That was my issue. Run all day then freeze at night. Also due to the air it would get thrown around and then lodge. Go here and see the pictures about 2/3 down.

HVAC

Also I just re-read your post.At work we warranty our installs for two or three years depending on brand. Manufactures have 5 or ten years on compressors. Call the company that installed it.
Posted By: 340Cuda

Re: Who's Central A/C knowledgeable? - 07/19/19 03:17 PM

For about $90 per year per unit I have a company come out twice a year to clean and run diagnostics on our HVAC units.

I think it is money well spent and has prevented further problems down the road.

I would also agree with an earlier post that your unit may still be under warranty.

While I think it is unlikely that you would have any sort of utility cut back on your system, if you did it would most likely be effective between 2:00 and 7:00 pm when loads peak.
Posted By: MONC

Re: Who's Central A/C knowledgeable? - 07/19/19 04:56 PM

Okay so no utility connections that I could see.
The drain hose looked clear / clean .

When I got late yesterday afternoon, the A/C was on, but NOT blowing well at all ( like I have been experience at night) .
So I took a look at the unit outside , and the coil looked pretty frozen .
I got the ice off with the hose, let it sit awhile then started the A/C again, and it seemed to blow better but not fully.
I ended it up turning it off before going to bed , and when I woke up this morning turned it on, and it blew cold with good air flow from vents.

I agree having a maintenance schedule set up for 90 /100 a year is a good idea, and will pursue that route.
I do NOT want the so-called experts who installed it back to the house, I went through a lot with them, and have concluded they are no experts.

So my question is what causes the coil to freeze like that?
It didn't happen last season ?

Thanks
Posted By: 3hundred

Re: Who's Central A/C knowledgeable? - 07/19/19 05:00 PM

Originally Posted by MONC
So my question is what causes the coil to freeze like that?
It didn't happen last season ?

Thanks


It's low on freon / coolant, whatever they install these days. Gotta be a leak. 2¢

Robert
Posted By: MONC

Re: Who's Central A/C knowledgeable? - 07/19/19 05:06 PM

Originally Posted by 3hundred
Originally Posted by MONC
So my question is what causes the coil to freeze like that?
It didn't happen last season ?

Thanks


It's low on freon / coolant, whatever they install these days. Gotta be a leak. 2¢

Robert


Is there a valve that shows the refrigerant level?
How long should the refrigerant last before having to refill / recharge?


Posted By: MONC

Re: Who's Central A/C knowledgeable? - 07/19/19 05:07 PM

Also , after shutting off the A/C entirely at the thermostat, I am still able to turn on the fan manually.
When I do that, the air flow is still weak.
This is why I was thinking it was the blower fan.
Posted By: wingman

Re: Who's Central A/C knowledgeable? - 07/19/19 05:12 PM

Originally Posted by 3hundred
Originally Posted by MONC
So my question is what causes the coil to freeze like that?
It didn't happen last season ?

Thanks


It's low on freon / coolant, whatever they install these days. Gotta be a leak. 2¢

Robert


Freezing coil can be caused by low refrigerant OR poor airflow.
Posted By: MONC

Re: Who's Central A/C knowledgeable? - 07/19/19 05:36 PM

I just read it could also be a faulty thermostat.

We have had to replace that thermostat before, and I do have a brand new replacement .
Since it's an easy plug and play device, I will try that over the weekend .
Posted By: 340Cuda

Re: Who's Central A/C knowledgeable? - 07/20/19 02:53 PM

Since you don't want the original installers back you might look for highly rated company that sells the same brand that you have.

That might insure that if there is something that is covered by warranty they could handle the claim.
Posted By: RWG75

Re: Who's Central A/C knowledgeable? - 07/20/19 03:46 PM

The outside coil should only freeze up in cold weather and that certainly hasn't been happening around this part of the world lately. Newer units should also have a defrost mode to get rid of it when it happens. No clue what's up with that but I'm not an a/c tech - I've just gone a few rounds with my heat pump. A long shot that comes to mind in the reversing relay. In my old system it was part of the inside unit, not sure where it is with the new one.

This is where I prove I'm not an a/c tech because I forget exactly how the thing works. Best I can give you is that when you put the system in heat mode, the relay is in one position and the system operates so that the hot side is in front of your circulation fan. When you put the system in cool mode, the relay goes to the other position and the system operates backwards putting the cold side in front of your circulation fan. With my previous system the default relay position was heat so when spring came around and I switched it over to cool, the stuck relay didn't let the refrigerant flow change directions.

See if you find something like that on the schematic and then figure out what it's default position is. Relays are more likely to fail than be intermittent but rapping it a couple times with a screw driver handle could pop it loose if it's stuck. Had a fan relay fail like that once. Worked for a couple days, needed another slap, worked for a couple more days, replacement eventually showed up.

A fowled up thermostat calling for heat when it should be calling for cooling seems possible and since ya have another one....
Posted By: Sniper

Re: Who's Central A/C knowledgeable? - 07/20/19 05:33 PM

low on freon usually freezes up the evaporator not the condenser.

So if there's a puddle on the floor in the house, that's the evap.
Posted By: rarefish

Re: Who's Central A/C knowledgeable? - 07/20/19 08:37 PM

Originally Posted by MONC
Originally Posted by 3hundred
Originally Posted by MONC
So my question is what causes the coil to freeze like that?
It didn't happen last season ?

Thanks


It's low on freon / coolant, whatever they install these days. Gotta be a leak. 2¢

Robert


Is there a valve that shows the refrigerant level?
How long should the refrigerant last before having to refill / recharge?


There is no valve that shows refrigerant level. The proper charge is check by temperature and pressure readings.
Refrigerant does not wear out with age. You only have to recharge when the system is opened for service or you develop a leak in the system. Hopefully the leak is found and repaired before recharging.
Posted By: slantzilla

Re: Who's Central A/C knowledgeable? - 07/21/19 12:15 AM

Mine was freezing up the evaporator after running about 1/2 day too. Had a service come out and it was 1 lb. low on freon. He topped it off and it's been good since.
Posted By: MONC

Re: Who's Central A/C knowledgeable? - 07/21/19 08:53 PM

Well, I changed the thermostat early yesterday morning before the hottest day of the year in our area to date.
The system ran all day , and as I kept an eye on it while I was working on another project in the basement.
The lines did not freeze, the drainage hose discharged as it was supposed to as well.
Let it go into the night and it seemed to run fine, blew good and cold all evening.
I checked the lines this morning and no freeze up at all.
It shuts off when it reaches thermostat set temperature, and restarts when it should.
It has been good all day today as well.
Not sure what the old thermostat was doing , but it so far the new one seems to have done the trick .
I did look for any loose insulation in the condensor unit and saw nothing ( this was before I installed new thermostat ) .

Will obviously keep an eye on it, but so far so good.
Thanks for all your advice, will come back to it if I have further issues .
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