A/C blowing too soft

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Old 06-27-15, 03:32 PM
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A/C blowing too soft

OK, I have researched this a bit online and read a couple of threads here. I think I am at the point where I need to get some advice for my particular situation.

So a few weeks ago I noticed the A/C was struggling late in the afternoon to keep up with the summer heat. The house stays as cool as I desire from about midnight to about 3 PM. But around 3PM, the summer heat (highs in the low to mid 90's lately) is apparently too much for it now. The A/C blows non-stop from 3 to around midnight, and then it gets caught back up again. It did fine last year and the year before.

The output from the vents is very soft. However, the input vents appear to be pulling the air in as strongly as ever. I have some MERV 8 air filters, but after reading around I went out today and got the cheapest accordion-type filters that I could get at Wal-mart, (1" thick, 3.94 cents each), which many suggest are better because they do not impede the air inflow as much.

Unfortunately, that does not appear to have fixed the problem. The output is still weak and here at 5:30 PM, the A/C has fallen behind and it is starting to get warm in the house.

I also got some Tri-Clean 2X Coil Cleaner a few weeks ago and sprayed down my external A/C unit according to the instructions. So, that has also been done.

I went into the attic to inspect the A/C unit, including inside the metal panel that you can open up, but I could not see anything obviously wrong. I am about an average level of handy, but I do not have any experience trying to troubleshoot or fix my own A/C.

Any help you guys could provide would be much appreciated.
 
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Old 06-27-15, 04:57 PM
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Well , you have to determine is the problem is truly not enough air flow ? Or some other problem ? Or both ?

Get an inexpensive " refrigeration thermometer " .

Search results for: 'thermometer'

Take the temperature of the return air , at the time the unit is struggling . Also the temperature of the air leaving the supply vent , closest to the air handler / furnace . Outside air temperature . Temperature of the air exhausting the top of the condenser unit . Temperature of the small copper refrigeration line , leaving the condenser . Temperature of the large copper line leaving the furnace coil / evaporator coil / A-Coil .

All this with the new filter installed . Repeat the temperature measurement at the first vent , with the filter off . Did it change the temperature ? ( I do not think so . ) Put the filter back in place .

You may or may not need to clean the indoor coil / A-Coil / Evaporator coil .

God bless
Wyr
 
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Old 06-27-15, 05:10 PM
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Wyr,

Thanks for your reply.

I have a thermometer. How do I identify these locations to measure the temperature:

1. Supply vent
2. Condenser unit (is that the outside unit?)
3. Small copper refrigeration line
4. Large copper line leaving the evaporator/A coil

Thanks.
 
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Old 06-28-15, 03:01 AM
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1. Supply vent

These are the vents / registers that blow cool / cold air ( warm / hot air when the system is in heating mode ) into the rooms / living space . Usually in the ceiling , sometimes in the floor or walls . Check it at the one closest to the furnace / air handler .

2. Condenser unit (is that the outside unit?)

Yes , this is the outside unit .

3. Small copper refrigeration line

At the condenser unit / outside unit , there should be 2 copper refrigeration lines coming from the house into the unit . The larger one should be insulated . The smaller one probably is not .

4. Large copper line leaving the evaporator/A coil

Those 2 copper lines end up going to the furnace / air handler . I think you said it is located in the attic ? They should be going into a " box " at the end of the furnace , from which the air flows ( and continues down the supply ducts ) . Stick the end of the thermometer under the insulation ( that should be on the larger of the 2 refrigeration lines ) so it contacts the copper tubing / line under the insulation .

The other end of the furnace sucks in the return air from the house . It is where the filter is located .

I may be able to tell you a little from the temperature readings . More knowledgeable folks on this forum can probably tell you more .

While you are in the attic , inspect the duct work as best you can . Look and listen for air leaks from the ducts . Look for ducts that may have been squashed by some one working in the attic . That might or might not make a different sound , as the air is forced past a restriction .

I think you said you removed a sheet metal panel / cover . was it one that reveled the cooling coil / evaporator coil / A-Coil ? Did all look well . It may or may not need cleaning . Was the blower fan running at the time ? If so , there should have been a lot of air coming out the side where you removed the cover / panel .

God bless
Wyr
 
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Old 06-28-15, 04:21 PM
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Wyr,

OK, I was planning to take temperature measurements today, but it rained and has been cloudy all day, so it did not get hot like it usually does. I will try again, hopefully tomorrow.
 
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Old 06-29-15, 05:03 AM
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If the return-air seems to be stronger than what the supply is delivering, then there must be severe duct leakage.

Check the entire duct system for leaks.

While you are in the attic , inspect the duct work as best you can. Look and listen for air leaks from the ducts. Look for ducts that may have been squashed by some one working in the attic. That might or might not make a different sound , as the air is forced past a restriction. - WyrTwister
 
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Old 07-05-15, 03:34 PM
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Well , you have to determine is the problem is truly not enough air flow ? Or some other problem ? Or both ?

Get an inexpensive " refrigeration thermometer " .

Search results for: 'thermometer'

Take the temperature of the return air , at the time the unit is struggling . Also the temperature of the air leaving the supply vent , closest to the air handler / furnace . Outside air temperature . Temperature of the air exhausting the top of the condenser unit . Temperature of the small copper refrigeration line , leaving the condenser . Temperature of the large copper line leaving the furnace coil / evaporator coil / A-Coil .

All this with the new filter installed . Repeat the temperature measurement at the first vent , with the filter off . Did it change the temperature ? ( I do not think so . ) Put the filter back in place .

You may or may not need to clean the indoor coil / A-Coil / Evaporator coil .

God bless
Wyr
Wyr,

Thank you for your patience. It got unseasonably cool for a few days, and then I got sidetracked until today. Here are the measurements that you told me to take:

1. Return Air - 80
2. Supply vent (with/without filter) - 70/70
3. Outside temperature - 92
4. Condenser unit (Top) - 102
5. Small copper refrigeration line - 89
6. Large copper line leaving the evaporator/A coil - 90

While you are in the attic , inspect the duct work as best you can . Look and listen for air leaks from the ducts . Look for ducts that may have been squashed by some one working in the attic . That might or might not make a different sound , as the air is forced past a restriction .

I think you said you removed a sheet metal panel / cover . was it one that reveled the cooling coil / evaporator coil / A-Coil ? Did all look well . It may or may not need cleaning . Was the blower fan running at the time ? If so , there should have been a lot of air coming out the side where you removed the cover / panel .
I inspected the duct work and it all looked good as best I could tell. I would have needed to be elastic man to get back there and see all of it. Which unfortunately in this instance, I am not.

I removed the metal panel by hand again on the side of the attic unit. It kind of hooks in and slides out, without any bolts or screws. There was no filter around there of any kind that I could see, nor was there any air coming out of the side of the attic A/C unit. The blower was and is running.

There were two red lights on the electronic control unit for the attic A/C that said that Dampers 3 & 4 were closed. I do not know it that is relevant, or if perhaps they are supposed to be closed.

There is air coming out of the supply vents, but it is just softer than I remember it. In any case, the house is not staying cool and it is not unusually hot out for this time of year at all.

I also got the model number of the attic unit, in case that might be helpful. It is a Lennox model CH33-50/60C - 2F - 2

Thanks,

Spartacus
 
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Old 07-05-15, 03:58 PM
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I believe this is the documentation from Lennox (pdf file) for the evaporator coil:

http://www.lennox.com/pdfs/installat...x_CH33_IOM.pdf
 
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Old 07-05-15, 05:18 PM
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I'm sorry if I missed it, but how old is the system? There could be several variables at work here. Capacitors, blower motor, air flow, restrictions, open duct runs, freon levels, components overheating, etc. I'd put a meter on it and check your run/start and fan capacitors, check the amperage on all your motors (condensing fan, blower), etc.

You can PM me with any questions. Good luck!
 
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Old 07-05-15, 05:26 PM
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NJHVACTECH,

It was installed in 2008. As far as your meter recommendations, I do not know how to do that yet.

Did the temperatures and other information I posted above say anything to you?

Thanks,

Spartacus
 
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Old 07-05-15, 06:54 PM
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RESPONSE TO YOUR TEMP NUMBERS:

Evaporator Unit appears to be a 4-Ton, condenser could be a 3 or 4-Ton.

First, we need an indoor %Relative humidity reading as that affects both indoor & outdoor temp-splits.

At 50% indoor RH coil-temp-drop should be 19F, it is only 10F.
Condenser if a 13-SEER, split should be around 17F or more, it is only 10F.
Subcooling was 13F; all results seem to indicate a light load on the indoor coil, perhaps due to too low an airflow.

The system is way under performing; find out what is causing the low airflow!
 
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Old 07-05-15, 07:51 PM
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all results seem to indicate a light load on the indoor coil, perhaps due to too low an airflow.
HVAC Retired,

So, what does what mean exactly and how do I do that? I have the cheapest, least-imposing filters in the three in-house air-intake vents. As far as I can tell, the ducts appear to be fine. I would prefer not to go out and buy a whole closet full of air-conditioning testing equipment if possible, so if there is something I can do to try to solve this that does not cost an arm and a leg, that would be preferable.

Could it be the two closed dampers (number's 3 & 4) that are the problem?

Thanks,

Spartacus
 

Last edited by Spartacus; 07-05-15 at 08:13 PM.
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Old 07-05-15, 09:14 PM
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Low freon can cause those problems too. You need to call an AC tech to check the charge level. If it is low, then you may have a leak.
 
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Old 07-06-15, 05:06 AM
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Flip the breaker off to the furnace & check the blower wheel blades for lint build-up.
If there is lint build-up on blower blades then the evaporator coil may be lint clogged...

Is the blower on the high-speed tap?
If it's a permanent-split-capacitor blower motor, is the blower motor capacitor okay & the correct MFD, or is the blower not coming-up to speed for some other reason?

Try opening those dampers to see if the helps any; doubt that's the problem.
You need an indoor humidity monitor & a good thermometer to check some temps; that's all, & those are very low cost.

If the coil freezes-over 'due to' low refrigerant charge or clogged indoor coil or way too low an airflow; the result is low airflow.

You have to be able to see the bottom-side of the indoor coil; it should be cleaned the best you can...
 
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Old 07-06-15, 05:28 AM
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I am confused by the 2 red indicator lites indicating damper issues ? Would this be a zoning controller connected to remote motorized dampers ?

Could you please post a photo of this control board ?

I am confused by the 90F temp of the large / suction / vapor copper line leaving the A-Coil / evaporator coil ? With 80F return air temp and 70F at the supply ?

Would some one more knowledgeable than I , please help me out here ?

Would be nice to have pressure information to compare this to .

Has any one else messed with the system , since last time it performed correctly ?

God bless
Wyr
 
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Old 07-06-15, 07:41 AM
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I am confused by the 2 red indicator lites indicating damper issues ? Would this be a zoning controller connected to remote motorized dampers ?

Could you please post a photo of this control board ?
It is a Lennox Harmony III Zoning System. Here is a PDF File of the Homeowners Manual for this unit, which has a clearer picture of the unit.



The four lights on the bottom left are for Dampers 4, 3, 2 & 1, respectively. I have seen it with the "Dampers Closed" lights for 4 & 3 lit while the A/C is on (they are all off except the green status light when it is idle) and I have seen it when the "Dampers Closed" 4, 3 & 1 lights are lit when it is on. I am not sure how many active zones that I have, or how that works, exactly.

I am confused by the 90F temp of the large / suction / vapor copper line leaving the A-Coil / evaporator coil ? With 80F return air temp and 70F at the supply ?
The poster HVAC RETIRED spoke to that in an earlier post. His comments about the temperature differentials suggested that my A/C is struggling to do its job, "way under performing" to use his words. But that did not tell me how to fix it.

I was hoping to be able to do this myself, but I am starting to wonder if that is going to be possible.

Thanks,

Spartacus
 
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Old 07-06-15, 08:03 AM
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The poster HVAC RETIRED spoke to that in an earlier post. His comments about the temperature differentials suggested that my A/C is struggling to do its job, "way under performing" to use his words. But that did not tell me how to fix it.

I was hoping to be able to do this myself, but I am starting to wonder if that is going to be possible.
Thanks, Spartacus
I told you some things you could do or get someone to help you do; if you can't do them about the only option is to call a contractor. I'm sorry but there are limits here...
 
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Old 07-06-15, 08:11 AM
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I told you some things you could do or get someone to help you do; if you can't do them about the only option is to call a contractor. I'm sorry but there are limits here...
I do appreciate your help.

I was hoping there would be something pretty easy and straight forward I could do to fix this, as it is my experience with cars, home repairs, computers, etc., that about 90% of the time, what is wrong is pretty easy to resolve if you can just figure out what the problem is and identify the basic procedures to fix it. The other 10% you either need to be ready to commit some real time to learning new skills, or get a professional to help you.

Thanks,

Spartacus.
 
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Old 07-06-15, 10:10 AM
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OK , you have a zoning panel . And do not know how many zones you have ?

Couple of thoughts . How many larger ducts do you have branching off the supply plenum ?

Another would be to take the cover off the zoning panel & looking to see if any cables are terminated for zones 3 & 4 .

I am wondering if there is a " master " damper for the whole system ?

When I get time , I will try to study the pdf .

God bless
Wyr
 
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Old 07-06-15, 10:20 AM
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As mentioned by Wyrtwister, the following does not make sense. If 90 there, how can you get 70 at the supply vent and 80 at return ? Are you sure you measured it right and measured at the right vent ?

*****6. Large copper line leaving the evaporator/A coil - 90 *****
 
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Old 07-06-15, 11:43 AM
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Thanks, guys. I think I am just going to have someone come fix it.
 
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Old 07-06-15, 02:15 PM
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Not a lot of info in the pdf that really helped me .

How many tstats do you have . Seems to indicate you can have one per zone or if set to central , one " master " tstat .

What puzzles me even more is it seems to say the tstats can be set differently ? Really be wild if some one sets 1 for heat & some one else sets another to cool ?

This is probably too involved to diagnose long distance .

But please post back and let us know what was wrong , once it all gets fixed .

God bless
Wyr
 
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Old 07-06-15, 05:20 PM
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AC guy just left. He says I have a tiny leak in my coil and my freon is low. He wants to bid to replace the coil. I told him to fill up the freon. He ran out of freon and will be back in a few minutes to finish the job.

I do not want to buy a new coil if I can avoid it. I have not seen the bid yet, but this is going to be expensive. Perhaps I should consider get some 410 freon charging equipment and just put that task on my annual maintenance routine.

What do you guys think?
 
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Old 07-06-15, 05:44 PM
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5 pounds of freon at $40 per pound = $200 + the service cost of $59?

That was more than I was expecting to refill the freon.
 
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Old 07-06-15, 09:58 PM
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Perhaps I should consider get some 410 freon charging equipment and just put that task on my annual maintenance routine.
R-410A is not compatible with R-22 which is what your older unit requires. Further, you need a certification from the Environmental Protection Agency in order to purchase R-22.

You could get the certification and buy a 30 pound jug of R-22 for about $300-350. and also spend about $50-100 for a manifold gauge set but that STILL won't be enough if you have to do anything more than simply add refrigerant.
 
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Old 07-07-15, 12:05 AM
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If it is 410a,yes, you can do it yourself. hope the leak is very small, otherwise you will be there every week if not every other day.
 
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Old 07-07-15, 02:24 AM
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Is it cooling properly , now ?

If you are serious about DIY your own A/C work , start now studying & researching .

If I can help ( I am just a DIY'er ) feel free to holler at me .

Hope it will be quite a while before it needs charging again .

God bless
Wyr
 
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Old 07-07-15, 02:59 AM
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I watched the guy fill it up. It is 410A. It was in a pink tank.

Wyr,

Yes, it is cooling great.

Thank you to everyone for trying to help me with this.

Spartacus
 
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