air conditioning used to cool 15 degrees now only 4

[whimser]

Suddenly a 1.5 year old carrier air conditioning unit at my house that used to rapidly cool the house 10-15 degrees is now only able to cool it 2-4 degrees.

A serviceman came out and checked the freon and amperage and differential and some other stuff and said the unit is working perfectly. They measured the output at the nearest vent and it was 46 degrees on a 65 degree day.
The air coming out seems cool but the house just will no longer cool down?

Question 1. What could cause this if the unit seems to be working.
Question 2. If the temp outside is 64 should my air conditioner be able to get the house to 54 or does it only lower it 10 degrees if it's 80 in the house down to 70.

Any experts have any ideas. I've been reading up on air conditioning and nothing seems to make any sense.

Thanks,

Dan
Homeowner

[timebuilder]

First, the coolest temp you should try to attain is a setpoint of about 69 in residential. There are some folks who want it cooler than that, and some equipment can indeed get you there, but 54 would be bordering on refrigeration.

Second, ask yourself, when did you perceive this change? The beginning of the season? On hot days only? After you heard a noise form the system?

My point is that if the parameters are in place, and there was no work performed, then a supply temp like 46 should be cooling your house.

It may be time to get another opinion, since we generally can't rely on readings that we haven't taken ourselves.

My gut is telling me there is more to the story. Not that you are deceptive, mind you, but that there may be other pieces to this puzzle.

[udarrell]

How high was the humidity in the house at 54F?

Never try to get the indoor temp that low, especially on a cool day.

Try it again when the weather is hot With a 75 to 80F indoor temp & 50% indoor relative humidity. The temp drop should be around 18 to 20F depending on where & how you take the temp.

How energy efficient your home duct system, etc., is determines how much temp drop it will get below the outside temp.

[wahoo]

Maybe we don't understand your post. Do you actually keep your home at 54 degrees? Most AC units are not designed to operate at this low an inside temp. What part of the country do you live in?

[Supertech_newb]

Well, I think it's clear. Replace your refrigerator instead of using your air conditioner to keep your food cool and preserved.

[whimser]

Thanks for the jokes and questions.

Here are some clarifications. The day we were testing it was not hot so I was trying to see how much I could cool the house below the ambient temperature and how long it would take. It was 65 and I was hoping it would drop to 55.

I could only get 4 degrees cooler than starting temp of 65 it went down a few degrees.
On another day at 83 it went down to 79, but while doing so the outside temp also dropped a few degrees so it's hard to say if it's doing anything.

It's certainly not 15-20 degrees although I thought that's what it used to do though. It used to cool the house down in a half hour about 10-15 degrees.
Now it does about 4 even though it checks out fine.

Dan

[Rob_in_WV]

Did the technician by chance share any of his readings with you or discuss his findings with you? it would be nice to know what he saw and then we might be able to spot a human error or oversight.

[C Combs]

check your airflow. Check all registers for airflow and make sure your return is getting indoor air not attic air. Make sure you have a clean filter and all registers are open with air blowing out of them. Next make sure your outdoor condenser has hot air (warmer than ambient) coming off the top of it from the fan. If both of the previous steps are done and OK then call your service tech because the next steps require the tools and skills of an HVAC technician

[udarrell]

check your airflow. Check all registers for airflow and make sure your return is getting indoor air not attic air. Make sure you have a clean filter and all registers are open with air blowing out of them.

Next make sure your outdoor condenser has hot air (warmer than ambient) coming off the top of it from the fan. If both of the previous steps are done and OK then call your service tech because the next steps require the tools and skills of an HVAC technician

Good advice.

Also, buy a humidity gauge at a hardware store.
When it is 78F & 50% or higher humidity in your home, a 10 or 12-SEER condenser will normally have an 18 to 20F air temp rise off it.

It appears the indoor coil is not absorbing an adequate heatload.
The condenser test will provide a clue concerning how much heat is being discharged to the outdoors.

You will need to find a competent Tech to verify & fix any problems.

[whimser]

I think that the fan on the unit is blowing out ambient temperature air, not hot air. It feels almost the same. I'm going to get a gauge and measure it and I'll report back.

Is it possible for the unit to check out fine in terms of typical measurements that a typical technician would make and still have a problem?


Thanks for all the input,

Dan

[timebuilder]

I think that the fan on the unit is blowing out ambient temperature air, not hot air. It feels almost the same. I'm going to get a gauge and measure it and I'll report back.

Is it possible for the unit to check out fine in terms of typical measurements that a typical technician would make and still have a problem?


Thanks for all the input,

Dan

1) There is no "typical" tech. However, you want a competent tech. It may be an opportunity for a second opinion.

2) Without heat load, you can't test the system properly. No system would respond in the manner you expected under those conditions.

What were the conditions on the day you decided to call out a contractor?

[dan sw fl]

If you know that the Temperature Difference changed from 15 to 4,
you KNOW
the unit is Very Ill.

[timebuilder]

If you know that the Temperature Difference changed from 15 to 4,
you KNOW
the unit is Very Ill.

I don't think that's what he said.

He said it used to cool 15 decrees on a day where cooling was required.

They he said he tested it on a day with no heat load and got 4 degrees.

Not the same thing.

I think most of us can imagine what happened on the day without heat load as he ran the unit continuously......

[dan sw fl]

I don't think that's what he said.

He said it used to cool 15 decrees on a day where cooling was required.

They he said he tested it on a day with no heat load and got 4 degrees.

Not the same thing.

I think most of us can imagine what happened on the day without heat load as he ran the unit continuously......

Post # 6

" ...
I could only get 4 degrees cooler than starting temp of 65 it went down a few degrees.
On another day at 83 it went down to 79, but while doing so the outside temp also dropped a few degrees so it's hard to say if it's doing anything. "

With 83'F inside, the diffusers ( vents) should provide air at about 61- 65'F.
I guess clarification is not clear.

[kwilcox]

years ago the same thing happened to me... then I flushed out my condenser coil. Could it be that simple?

[timebuilder]

Post # 6

" ...
I could only get 4 degrees cooler than starting temp of 65 it went down a few degrees.
On another day at 83 it went down to 79, but while doing so the outside temp also dropped a few degrees so it's hard to say if it's doing anything. "

With 83'F inside, the diffusers ( vents) should provide air at about 61- 65'F.
I guess clarification is not clear.

No, it isn't.

We have no idea how long the system was permitted to run before that reading was taken, do we? What else was going on? What kind of other variables are in play that could have kept the heat load from the evaporator?

Nope. Clear it is not.

[sktn77a]

Is it possible for the unit to check out fine in terms of typical measurements that a typical technician would make and still have a problem?

Not if the tech knows what he's doing. Your first post said "They measured the output at the nearest vent and it was 46 degrees on a 65 degree day". 65 degrees inside the house, or 65 degrees outside? If the former, that's a 19 degree differential which is good (if you don't have a plugged filter). You now say it's blowing ambient temp air - ie differential of zero. Which is it?

[jpsmith1cm]

I think most of us can imagine what happened on the day without heat load as he ran the unit continuously......

I don't think it is a problem to tell him. If you try to run an AC unit too cold, the coil temperature drops below freezing. Then the coil starts to build ice fairly rapidly. This tends to be very bad for compressors. It is also why AC equipment cannot maintain temperatures much below 70 degrees F.

years ago the same thing happened to me... then I flushed out my condenser coil. Could it be that simple?

A competent technician would see this in an analysis of the system.

[timebuilder]

I one heard about a guy who was told his coil was frozen, so he decided to clear the ice himself when the tech left.

With an ice pick.

I'd rather the guy called that "competent" tech, perhaps from another company.

[vibration]

It's certainly not 15-20 degrees although I thought that's what it used to do though. It used to cool the house down in a half hour about 10-15 degrees.
Now it does about 4 even though it checks out fine.

I really doubt this, the reason why the OP thought the ac was wrong.