AC / Heat Pump FAQs

Lost Cooling Capacity Q&A
Air condioner / heat pump problems

My air conditioner takes too long to cool down my condo. Why?

My HVAC is around 15 years old. I have lived in my condo for 3 years now, so I wasn't living here when it was installed. It always reached the set AC temperature within a few minutes and I always leave the thermostat on "auto".

Recently it started taking hours to reach the set temperature and until it reaches that temperature, it doesn't turn off and on even though it's set on auto. It does run cold though. I also recently had the capacitor replaced.

I asked the technician who replaced the capacitor why it's doing that, but he just said I need a new HVAC and couldn't tell me why it's doing that.

Do you happen to have any idea why it's taking so long to reach the set temperature? I don't want to have it replaced until it stops working altogether. On 2018-06-06 by Jill

Reply by (mod) -

I would start at LOST COOLING CAPACITY: DIAGNOSTIC GUIDE A/C or HEAT PUMP

for help in diagnosing and repairing the trouble ypu describe

Check air flow and temperaturee drop across the cooling coil.

Followup by Jill

And I just used the word "compressor" as being the problem when it could be the motor or something else (I read several things about it, but since I can't get on the roof, I can't check those things).

At this point, I just basically would like an opinion on whether or not I should continue to run it on auto until I have to have it replaced or would just letting it run continuously extend its life any? Thanks.

Thanks for the suggestion, but I don't know how to check things myself and part of it is on the roof, so if I decide to use the AC until it breaks down completely and I have to get a new one, am I better off leaving it on auto or just let it run all the time as far as if the compressor happens to be failing goes?

I say that because now it seems to be having more trouble starting up after it has been off between cycles.

Reply by (mod) -

Right - not even the service techs use consistent language. And yes, stay off the roof.

Check for reduced air flow at the supply registers

Check then for a dirty air filter


Check then for blocked, disconnected air ducts

 

What if my indoor unit has a higher BTU rating than my compressor?

What if my indoor unit has higher BTU than my compressor? i suspect the installer has fixed the wrong unit - 011-08-06 by Alan

Reply by (mod) - check with the manufacturer after getting the actual BTUh numbers

Alan, if the numbers are close the system may be adequately balanced;

I'd write down the data tag information from both the compressor/condenser unit and the air handler unit, then give the manufacturer's customer support line a call to ask their opinion.

Let us know the specifics of what you read on the data tags and what the manufacturer says.

A/C or Heat Pump Dehumidification or Humidity FAQs

New compressor unit won't dehumidify our home

I recently had a 3 1/2 T Payne Dual HeatPump/AC installed in Dec 2017. Heat worked perfectly. However in early July the compressor went bad.

The air compressor was replaced with a new one. Since the new compressor has been installed it is cycling 5 minutes on and 20 min off.

The temperature is cooling; however the humidity in the house has varied from 50-58% in 90-100 degree temperatures.

Service tech checked unit for 2 hrs. He stated since the compressor was cooling everything was ok.

I don't agree with him and I don't think he knows how to fix it. This unit is still under warranty. Actually only used 6 months. - On 2018-07-20 by Lilian

Reply by (mod) -

Lillian

If the compressor unit is over-sized it will cool adequately but won't run long enough to dehumidify.

Why does humidity go up in our basement when the air conditioner is running?

Any thought on why the RH in the basement would increase by appx 10% when the unit is running.

Trying to keep the RH in check due to having to replace duct work due to mold.

No visual signs of any leaks to the unit and it is doing it's job for the living area up stairs (1 floor).

Drain has trap on and goes into pump to sewer line. On 2011-06-03 by Mark

by (mod) - humidity problems - air starved?

Mark:

If the humidity in your basement is INCREASING when your air conditioner is running that's certainly unexpected as A/C should decrease the humidity.

If you can't find a water, moisture, or condensate leak somewhere I'd look at the return air duct system to see if the system is air-starved, creating negative pressure, and then drawing outside air into the basement.

Also, noting that you had a previous mold problem, I'd want to be very sure that any building sources of excessive moisture have been identified and fixed.

As an aside: if an A/C unit is not dehumidifying its building sometimes it's because it was not sized properly.

A unit that is too big will cool down too fast and won't run long enough to drop the Relative Humidity - but I wouldn't expect that problem to itself increase the RH.

by Mark

To the best of my know how the mold was from years of someone allowing the moisture to be present and a water issue that has been addressed with a swale on the exterior.

Even during period of heavy rain the RH will stay in check with the dehumidifier.

One thought is to seal the block walls again with drylock. Thanks for all your imput. still baffeled.

by (mod) - mold and condensate leaks

Mark

Sometimes with a sensitive RH meter you can track down moisture to an area of the building or a wall or floor.

Certainly moisture may be pumping through a foundation wall into the basement, and I agree that an interior moisture barrier sealant would help.

On our EXTERIORS section page you'll see WATER ENTRY in BUILDINGS where we list a number of diagnosis and repair/improvement articles that might help.

Don't assume that the swale alone is enough; For example even a small error in handling roof spillage can increase basement moisture even if you're not seeing wet floors.

Why is my A/C unit producing buckets of water?

My a/c unit inside is producing water by the bucket fulls. What causes this and how do I prevent it? On 2011-05-24 by Jo

Answer by mod

If you are seeing a lot of condensate produced by your A/C unit,

1. be sure that the condensate drain is not clogged, so that the condensate is disposed of properly

2. this is normal in hot humid weather

3. but you might have a source of unusually high indoor moisture, such as from building leaks, water entry, or even cooking or bathing.

Can a Goodman AVPTC49c14 be installed in a doublewide mobile home"

Can a Goodman AVPTC49c14 be installed in a doublewide mobile home. - On 2020-06-11 by LISA

If so would anything have to be modified?

Reply by (mod) - check the manual: it MUST say "approved for mobile home use" or "approved for manufactured home use"

If a heater is not listed and approved for mobile home installation, modifying it would be unsafe.

Is there an ambient temp safety sensor to protect the compressor in cold weather?

Do any AC systems have an ambient temp safety sensor that wont allow to compressor to turn on below a preset outside temperature? - On 2018-11-10 by robinsoninspections @gmail.com

Reply by (mod) - Yes, for example the SUPCO freeze protection switch, opens at 35 degF.

Rob

Heat pumps use outdoor temperature sensors for several purposes including switching the compressor motor OFF and switching to backup heat mode if outdoor temperature falls below the safe (or efficient) operating temperature of the unit (typically around 25-30 degF for most units).

An air conditioner unit, that is one that ONLY provides cooling, again depending on age and model, may NOT have any such outdoor temperature controllers.

Such units should be left turned off in winter.

If some fool tries to turn on the air conditioning at the indoor thermostat and if the outdoor unit runs in freezing weather it might be damaged by liquid refrigerant slugging in the compressor.

THose AC units do often include a crankcase heater to prevent liquid refrigerant slugging; that's why we leave power to the unit ON for 24 hours before actually asking the compressor motor to run at lower outdoor temperatures.

There are also "freeze protection kits" from Amana, Goodman, Supco, and others that provide an outdoor temperature sensor and that prevent the compressor from running at low outdoor temperatures.

Those can be retro-fitted to an A/C (i.e. not a heat pump) if needed. There are similar protection devices that can be fitted at the indoor coil to detect coil icing or freezing in that location, like the Amana FSK-01A kit.

Shown above SUPCO freeze protection switch, opens at 35 degF.