Home Page link

Need help diagnosing problem with A/C

Home| Search | About
Login Password
Register Now! Lost Password?

HVAC Discussions - Heating, ventilation and air conditioning. 

Page 1 of 8       1 2 3 > last >> Bookmark this page:  YahooMyWeb Yahoo!  Google Google  Windows Live Favorites Windows Live  del.icio.us del.icio.us  digg digg  Add to Netscape Netscape
Subject Author Date
Need help diagnosing problem with A/C tivolo 07-25-2006
If you were  Registered and logged in, you could reply and use other advanced thread options
Posted by tivolo on July 25, 2006, 11:11 am
I have a 6-year-old TempStar SmartComfort 2000 A/C unit that's
generally behaved well up until this year. But now we're having serious
problems and the two techs that have come out have not been able to
resolve the issue. I'm not electrically inclined and I don't know much
about HVAC in general, so I'm hoping someone might have some advice on
this problem.

Basically, the symptoms are these:

* From an off state, I turn on the thermostat to Cool and the
compressor starts up. About 20-30 seconds later, the blower on the
furnace comes on. The air's good and cold -- no problems so far.

* Anywhere from 10 to 30 seconds later, the compressor and fan click
off and then immediately back on. It repeats this 4 or 5 times, speced
anywhere from 5 - 30 seconds apart. After that, the compressor/fan
shuts down.

* As soon as the compressor stops, the furnace's blower kicks into high
gear. It is then impossible to stop the blower by means of the
thermostat. Turn it off, turn up the temp, turn it to heat, remove it
from the wal, ... the blower keeps going. To turn it off I have to use
the switch in the furnace cabinet.

* Now, even though it's off, if I turn the switch in the furnace
cabinet back on, the blower comes right back on (compressor/fan still
off) and will run indefinitely (as far as I know -- I've let it go for
an hour once before shutting it off again).

I end up having to wait anywhere from an hour to a day or more before I
find I can turn the switch in the furnace cabinet back on and NOT have
the blower start. At that point, I can restart the whole process: turn
on the A/C and the compressor comes on, etc.

The two techs that cme out both diagnosed the problem as the compressor
overamping. Here's their exact diagnoses:

Tech #1:
"Unit is way overamping. Rated at 18.6 amps, amping at 19.8 amps.
Overamping due to burned contact points and wrong size fuses."

Tech #2:
"While out by condenser running, compressor dropped out. When it reset
checked amp drain. Compressor is overamping, will need to replace."

The second tech said the burned contact points and fuse couldn't be the
problem and that the entire compressor would have to be replaced. Based
on other feedback I've received, the consensus seems to be that neither
tech is correct.

Thanks for reading all of that, and thanks for any advice you can give
me. I'm scheduling a third tech to come out but would like to have more
of a clue before he starts so hopefully I can steer him in the right
drection.

Thanks -
Ken


Posted by udarrell on July 25, 2006, 12:42 pm
tivolo wrote:

>I have a 6-year-old TempStar SmartComfort 2000 A/C unit that's
>generally behaved well up until this year. But now we're having serious
>problems and the two techs that have come out have not been able to
>resolve the issue. (Clipped)
>
>Basically, the symptoms are these:
>
>* From an off state, I turn on the thermostat to Cool and the
>compressor starts up. About 20-30 seconds later, the blower on the
>furnace comes on. The air's good and cold -- no problems so far.
>
>* Anywhere from 10 to 30 seconds later, the compressor and fan click
>off and then immediately back on. It repeats this 4 or 5 times, speced
>anywhere from 5 - 30 seconds apart. After that, the compressor/fan
>shuts down.
>
>
That sounds like a pressure control shutting down the unit then when the
pressure equalizes the control closes the contacts and the condenser
cycles back on.

>* As soon as the compressor stops, the furnace's blower kicks into high
>gear. It is then impossible to stop the blower by means of the
>thermostat. Turn it off, turn up the temp, turn it to heat, remove it
>from the wall, ... the blower keeps going. To turn it off I have to use
>the switch in the furnace cabinet.
>
>
>(Clipped)
>I end up having to wait anywhere from an hour to a day or more before I
>find I can turn the switch in the furnace cabinet back on and NOT have
>the blower start. At that point, I can restart the whole process: turn
>on the A/C and the compressor comes on, etc.
>
>The two techs that came out both diagnosed the problem as the compressor
>overamping. Here's their exact diagnoses:
>
>Tech #1:
>"Unit is way overamping. Rated at 18.6 amps, amping at 19.8 amps.
>Overamping due to burned contact points and wrong size fuses."
>
>
The compressor will nearly always pull more amps during the startup period.
If the contact points are burnt that will cause high resistance that
will reduce available voltage & thus spike-up the amps.
Voltage times amps = Watts. It may or may not be pulling excessive watts.

Voltage should be checked on each side of the contact points to
determine any drop.
The high amp draw may not be due to the contactor points!

>Tech #2:
>"While out by condenser running, compressor dropped out. When it reset
>checked amp draw. Compressor is overamping, will need to replace."
>
>
Was the condenser fan running? The compressor normally cycles on & off
on the overload independent of the condenser fan motor.
Pressures may not have equalized enough for the compressor to restart
without over amping for too long a time period.

Is the condenser clogged with cottonwood or other debris?

>The second tech said the burned contact points and fuse couldn't be the
>problem and that the entire compressor would have to be replaced. Based
>on other feedback I've received, the consensus seems to be that neither
>tech is correct.
>
>
That is also my consensus, neither tech is correct.
It is probably a simple fix for a good trouble shooting tech.
PJM is correct.
It appears that, especially the one condemning the compressor "might" be
pulling your leg for some quick cash.(?)
- udarrell

>Thanks for reading all of that, and thanks for any advice you can give
>me. I'm scheduling a third tech to come out but would like to have more
>of a clue before he starts so hopefully I can steer him in the right
>drection. Thanks - Ken
>
>
--
Air Conditioning's Affordable Path to the "Human Comfort Zone Goal"
http://www.udarrell.com/air-conditioning-total-heat-enthalpy-latent-heat.html
For Techs:
http://www.udarrell.com/ac-trouble-shooting-superheat-subcooling.html

Posted by tivolo on July 25, 2006, 12:52 pm
Thanks, udarrell --

When the compressor goes off, the fan always goes off as well. The
condensor doesn't look clogged with anything -- the fins look very
clear of deris inside and out.

One other thing I forgot to mention: sometimes when the compressor
shuts off it does so with a very strong "bang" -- it sounds like
someone kicked the side of the unit's cabinet. Also, from time to time
it will run just fine. For example, it ran for almost two days straight
this weekend before finally giving out. Since then, we can get it to
run for more than a couple of minutes (and usually less than 1 minute).

Thanks again -
Ken



udarrell wrote:
> tivolo wrote:
>
> >I have a 6-year-old TempStar SmartComfort 2000 A/C unit that's
> >generally behaved well up until this year. But now we're having serious
> >problems and the two techs that have come out have not been able to
> >resolve the issue. (Clipped)
> >
> >Basically, the symptoms are these:
> >
> >* From an off state, I turn on the thermostat to Cool and the
> >compressor starts up. About 20-30 seconds later, the blower on the
> >furnace comes on. The air's good and cold -- no problems so far.
> >
> >* Anywhere from 10 to 30 seconds later, the compressor and fan click
> >off and then immediately back on. It repeats this 4 or 5 times, speced
> >anywhere from 5 - 30 seconds apart. After that, the compressor/fan
> >shuts down.
> >
> >
> That sounds like a pressure control shutting down the unit then when the
> pressure equalizes the control closes the contacts and the condenser
> cycles back on.
>
> >* As soon as the compressor stops, the furnace's blower kicks into high
> >gear. It is then impossible to stop the blower by means of the
> >thermostat. Turn it off, turn up the temp, turn it to heat, remove it
> >from the wall, ... the blower keeps going. To turn it off I have to use
> >the switch in the furnace cabinet.
> >
> >
> >(Clipped)
> >I end up having to wait anywhere from an hour to a day or more before I
> >find I can turn the switch in the furnace cabinet back on and NOT have
> >the blower start. At that point, I can restart the whole process: turn
> >on the A/C and the compressor comes on, etc.
> >
> >The two techs that came out both diagnosed the problem as the compressor
> >overamping. Here's their exact diagnoses:
> >
> >Tech #1:
> >"Unit is way overamping. Rated at 18.6 amps, amping at 19.8 amps.
> >Overamping due to burned contact points and wrong size fuses."
> >
> >
> The compressor will nearly always pull more amps during the startup period.
> If the contact points are burnt that will cause high resistance that
> will reduce available voltage & thus spike-up the amps.
> Voltage times amps = Watts. It may or may not be pulling excessive watts.
>
> Voltage should be checked on each side of the contact points to
> determine any drop.
> The high amp draw may not be due to the contactor points!
>
> >Tech #2:
> >"While out by condenser running, compressor dropped out. When it reset
> >checked amp draw. Compressor is overamping, will need to replace."
> >
> >
> Was the condenser fan running? The compressor normally cycles on & off
> on the overload independent of the condenser fan motor.
> Pressures may not have equalized enough for the compressor to restart
> without over amping for too long a time period.
>
> Is the condenser clogged with cottonwood or other debris?
>
> >The second tech said the burned contact points and fuse couldn't be the
> >problem and that the entire compressor would have to be replaced. Based
> >on other feedback I've received, the consensus seems to be that neither
> >tech is correct.
> >
> >
> That is also my consensus, neither tech is correct.
> It is probably a simple fix for a good trouble shooting tech.
> PJM is correct.
> It appears that, especially the one condemning the compressor "might" be
> pulling your leg for some quick cash.(?)
> - udarrell
>
> >Thanks for reading all of that, and thanks for any advice you can give
> >me. I'm scheduling a third tech to come out but would like to have more
> >of a clue before he starts so hopefully I can steer him in the right
> >drection. Thanks - Ken
> >
> >
> --
> Air Conditioning's Affordable Path to the "Human Comfort Zone Goal"
> http://www.udarrell.com/air-conditioning-total-heat-enthalpy-latent-heat.html
> For Techs:
> http://www.udarrell.com/ac-trouble-shooting-superheat-subcooling.html


Posted by Bob_Loblaw on July 25, 2006, 4:38 pm


> * From an off state, I turn on the thermostat to Cool and the
> compressor starts up. About 20-30 seconds later, the blower on the
> furnace comes on.



The furnace blower should come on right away.



> * Anywhere from 10 to 30 seconds later, the compressor and fan click
> off and then immediately back on. It repeats this 4 or 5 times, speced
> anywhere from 5 - 30 seconds apart. After that, the compressor/fan
> shuts down.


The fact that both the compressor and the outdoor fan shut off , plus
the fact that your furnace fan is acting up, suggests to me that you may
have either a faulty thermostat, or a faulty circuit board on the
furnace.





> * As soon as the compressor stops, the furnace's blower kicks into
high
> gear.


It should be on high speed right from the start, unless it's a Coleman,
which for some reason known only to their engineers and God, the default
cooling speed used to be medium high.


>It is then impossible to stop the blower by means of the
> thermostat. Turn it off, turn up the temp, turn it to heat, remove it
> from the wall, ... the blower keeps going.

If, when you remove it from the wall you mean disconnect the wires from
it, then you have a faulty circuit board, or faulty t/stat wiring.




>To turn it off I have to use
> the switch in the furnace cabinet.
>
> * Now, even though it's off, if I turn the switch in the furnace
> cabinet back on, the blower comes right back on (compressor/fan still
> off) and will run indefinitely (as far as I know -- I've let it go for
> an hour once before shutting it off again).



Circuit board or t/stat wiring...




> The two techs that came out both diagnosed the problem
>as the commpressor overamping.



So why is the outdoor fan shuting down???
And why is the furnace fan delayed in starting, and running on for hours
after shut-down?

Furnace circuit board or thermostat wiring.
Is this a Carrier furnace by any chance, with an HK42 circiut board?


--
Respectfully, Bob

Posted by daytona on July 25, 2006, 5:09 pm
not necessarily.....could have a time delay on evap fan start up
gives the system a higher SEER rating


>
>
>> * From an off state, I turn on the thermostat to Cool and the
>> compressor starts up. About 20-30 seconds later, the blower on the
>> furnace comes on.
>
>
>
> The furnace blower should come on right away.
>
>
>
>> * Anywhere from 10 to 30 seconds later, the compressor and fan click
>> off and then immediately back on. It repeats this 4 or 5 times, speced
>> anywhere from 5 - 30 seconds apart. After that, the compressor/fan
>> shuts down.
>
>
> The fact that both the compressor and the outdoor fan shut off , plus
> the fact that your furnace fan is acting up, suggests to me that you may
> have either a faulty thermostat, or a faulty circuit board on the
> furnace.
>
>
>
>
>
>> * As soon as the compressor stops, the furnace's blower kicks into
> high
>> gear.
>
>
> It should be on high speed right from the start, unless it's a Coleman,
> which for some reason known only to their engineers and God, the default
> cooling speed used to be medium high.
>
>
>>It is then impossible to stop the blower by means of the
>> thermostat. Turn it off, turn up the temp, turn it to heat, remove it
>> from the wall, ... the blower keeps going.
>
> If, when you remove it from the wall you mean disconnect the wires from
> it, then you have a faulty circuit board, or faulty t/stat wiring.
>
>
>
>
>>To turn it off I have to use
>> the switch in the furnace cabinet.
>>
>> * Now, even though it's off, if I turn the switch in the furnace
>> cabinet back on, the blower comes right back on (compressor/fan still
>> off) and will run indefinitely (as far as I know -- I've let it go for
>> an hour once before shutting it off again).
>
>
>
> Circuit board or t/stat wiring...
>
>
>
>
>> The two techs that came out both diagnosed the problem
>>as the commpressor overamping.
>
>
>
> So why is the outdoor fan shuting down???
> And why is the furnace fan delayed in starting, and running on for hours
> after shut-down?
>
> Furnace circuit board or thermostat wiring.
> Is this a Carrier furnace by any chance, with an HK42 circiut board?
>
>
> --
> Respectfully, Bob



Page 1 of 8       1 2 3 > last >>
Similar ThreadsPosted
More customers diagnosing their own furnaces December 23, 2006, 10:55 pm
Problem ac July 3, 2006, 10:53 pm
Problem Update July 30, 2006, 12:52 pm
A/C problem, need help ASAP August 2, 2006, 10:37 pm
furnace problem December 5, 2006, 12:22 pm
roofing problem March 11, 2007, 10:48 pm
Condenser problem?? June 22, 2007, 10:17 pm
Janitrol A/C Problem June 26, 2007, 1:10 am
Stormy's problem ? September 27, 2007, 9:23 am
Thermostat Problem November 26, 2007, 12:44 pm

Contact Us | Privacy Policy

XML SitemapXML Sitemap