Heating and air conditioning - Variable Speed Blower Barely Runs on AC Settings

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Variable Speed Blower Barely Runs on AC Settings - Goodman Gaspack

Derek Mark Edding

2005-07-24, 9:13 pm

Hi Folks,

It looks like our 3 yo 12 seer Goodman combined AC/heat outdoor unit has
an installation problem. The compressor works great, but the variable
speed blower barely spins. When set to heat it blows just fine - very
powerfully. But set on AC, it feels like someone's waving a newspaper.

According to the HVAC Tech who visited this week, the refrigerant is
fully charged and the temperature measures 55 degrees F at the output
vents, 82-83 at the two intake vents.

Our digital thermostat shows that the compressor is running between 12
and 14 hours a day. We've had temperatures in the nineties for the last
three weeks, and this system is running hard enough to power a
whole-house refrigerator. We keep the thermostat at 78-79, but the best
it can do is four degrees above that.

The 12 seer unit is a replacement the original Goodman Comfortmaker
gaspack. When our installer removed the old one, he remarked that the
intake and output hoses were too small, and had been reduced in size to
12 inches which did not meet building code.

To the best of my knowledge, all of the homes in our neighborhood were
equipped this way. The original builder installed systems were
inefficient but functioned adequately. The replacement unit is
physically much larger, but at 3.5 tons is probably the same capacity
(we have no records for the original unit).

He removed the original "main trunk" of the ducting under the house -
plenum? Manifold? And replaced it with a much larger one that had 18"
pipes running to the outdoor gaspack. There was no change other than that.

After installing and powering on the new system in August three years
ago, we had the same problem we have now. The variable speed fan barely
ran when set to AC, but ran powerfully when set to heat. Our installer
had not installed this model before and had to consult with Goodman
repeatedly to fix the problem. He replaced the variable speed blower
unit, but this did not fix it.

What eventually did make a difference was this: he said that there was
an Air Mass Detector built into the variable speed blower, which is like
a humidity detector. He said that the air flow returning to the unit
was not sufficient, and this detector was keeping the fan from ramping
up to its full speed. He pointed to the intake duct inside the unit and
said that there was (and here my memory is sketchy) something like an
air flow restrictor, that he had needed to adjust to increase the
velocity of the air returning to the unit.

After he made this change, the blower began functioning normally and we
had decent cooling. However, this was towards the end of the Summer.
We had to call him back again last Summer for a similar problem, which
he said was "just needed a few pounds of refrigerant".

That brings us to this year, where we have unusually high heat and
humidity and again, the blower is back to barely running. The HVAC tech
who visited this week said that the unit appeared to be fully
operational and was not reporting any failure codes. He said he would
need to send an expert to examine our installation and determine if it
needs to be redone.

If anyone has any clues that might help us get this unit to run properly
I'd be very grateful. The fellow who did our installation did an
excellent job of taking care of our old system for ten years, but he
seems out of his depth with its replacement.

Thanks,

-dreq

Derek Mark Edding

2005-07-24, 9:13 pm

B-Hate-Me wrote:
> "Derek Mark Edding" <dreq@earthlink.net> wrote in message
> news:HZ6Ee.2826$6f.1880@newsread3.news.atl.earthlink.net...
>
>
>
> Why didn't you listen to the dude that TOLD you
> the ductwork was too small ?
>
> Fucking people never cease to amaze me.

If you always leap to the wrong conclusions, you'll always be amazed by
fucking people.

Where in the posting does it even suggest that I didn't listen to him?

He wrote an estimate for the full job, did everything he thought was
necessary, and got paid in full. No modifications. No alterations. End
of story.

-dreq

Derek Mark Edding

2005-07-25, 11:21 am

Bubba wrote:
> Here is a clue.
> Just Paypal me the $10 K in advance. I really dont think I'll need to
> show up on this one. I'll just phone it all in.

Hi Bubba,

The check's on its way. Thanks a lot for the help, it made my day. You
da man!

-dreq

Derek Mark Edding

2005-07-25, 11:21 am

Bob Pietrangelo wrote:
> The 11th word in your post including your greeting and all of the numbers
> included. Why do you think putting 5 tons of flex duct to your existing
> poorly designed duct work would change anything. Sounds like your
> contractor is an idiot. THe VS ircuit board determines the speed of your VS
> motor. It sounds like your motor and head are find. It's the brain not
> telling everything else to work properly. Why in the world would you buy
> goodman anyway.

Because the first one worked fine for seventeen years?

Thanks Bob.

-dreq

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