Air Conditioning Problems

[AquaMan]

My American Standard Allegiance 10 central air unit seems to have a bad contactor or a bad thermostat or both (google research). It hums sometimes and refuses to kick the compressor on. Then the next time it comes on just fine. It does cool. At least once it turned off before reaching the temp set on the thermostat. The unit is a 1997 model that has had some service work but I normally clean it up each year myself.

What should this cost me and does anyone have a contractor they trust? So many cheats out there right now. Thanks.

[DolfanBob]

Give Tom Hundley a call. It's a family business and he has been doing it quite awhile. 918-455-5993

[nathanm]

R&R Mechanical. They "saved" me a ton over some other guys who wanted to do a bunch of unnecessary work after my compressor took a dump some summers ago. My A/C is still working fine, 2 or 3 years later, despite not doing literally $3,000 worth of upsell crap that the other folks claimed was required by code. Nice guy, too. I forget exactly what the price was, but I think it was about $700 to replace the compressor, including the R-22.

[Hoss]

R&R Mechanical. They "saved" me a ton over some other guys who wanted to do a bunch of unnecessary work after my compressor took a dump some summers ago. My A/C is still working fine, 2 or 3 years later, despite not doing literally $3,000 worth of upsell crap that the other folks claimed was required by code. Nice guy, too. I forget exactly what the price was, but I think it was about $700 to replace the compressor, including the R-22.

This.  Owner is my uncles adopted son I believe.  He came out and fixed my a/c issue earlier last month before it got really hot.  Fan went out and needed 1/2 lb of R22.  250 dollars.  Super nice guy.

[patric]

My American Standard Allegiance 10 central air unit seems to have a bad contactor or a bad thermostat or both (google research). It hums sometimes and refuses to kick the compressor on. Then the next time it comes on just fine.

Look up "hard start kit" which is an add-on that extends the life of older or prematurely failing compressor motor starters.

[heironymouspasparagus]

Here is another one, if you want more selection;

http://www.alltempheatandcool.com/

He has done good, reasonable work for parts of the family for about 20 years (Mothers in both families go to church together). 


If you put the hard start on, I would strongly recommend that you go ahead and replace both the contactor AND the capacitor on the compressor (the hard start IS a replacement capacitor).  Look at the fan motor on the outside unit, too.  If it looks like it is "struggling" to turn on, change it's capacitor, too.  (I would just go ahead and change the cap anyway, no matter what.)  If you are having issues there, the inside unit probably needs a new cap on the fan motor, too.

1997 - you are at the end (past) of expected life of the equipment.

Locke Supply will have these parts, or Grainger (sometimes more difficult to buy parts from).

[heironymouspasparagus]

One other thing - if you still have one of those old style non-programmable thermostats, I would strongly recommend replacing it.  The programmables (Honeywell, etc) have a feature that you really do want - especially with an older unit.  It is a time delay after a power glitch such that the thermostat does not try to bring the compressor back on without a waiting period.  Like if lightning drops power for a second, the unit stops, then tries to come back on.  It is called an ASCD - anti-short cycle delay.

What it does is makes the system wait for 5 minutes before trying to turn on again.  Let's the pressure bleed down to an equalized condition, so that upon restart attempt, the compressor is not starting against high pressure.  Greatly reduces stress on compressor and increases life.  Many of the programmables will also enforce a minimum run time that you really want happening, too.  Once the compressor starts it won't stop for some time (3 minutes is typical) so that any oil that has been ejected from the compressor can make its way through the system back to the compressor.  Several quick start/stop cycles can empty a compressor of oil, causing serious issues - from increased wear and tear to catastrophic compressor failure.

Both of these features have been around in commercial systems for a long time, but just now coming to residential.  A new residential may have these built in to its control board, if you are lucky.

[Hoss]

One other thing - if you still have one of those old style non-programmable thermostats, I would strongly recommend replacing it.  The programmables (Honeywell, etc) have a feature that you really do want - especially with an older unit.  It is a time delay after a power glitch such that the thermostat does not try to bring the compressor back on without a waiting period.  Like if lightning drops power for a second, the unit stops, then tries to come back on.  It is called an ASCD - anti-short cycle delay.

What it does is makes the system wait for 5 minutes before trying to turn on again.  Let's the pressure bleed down to an equalized condition, so that upon restart attempt, the compressor is not starting against high pressure.  Greatly reduces stress on compressor and increases life.  Many of the programmables will also enforce a minimum run time that you really want happening, too.  Once the compressor starts it won't stop for some time (3 minutes is typical) so that any oil that has been ejected from the compressor can make its way through the system back to the compressor.  Several quick start/stop cycles can empty a compressor of oil, causing serious issues - from increased wear and tear to catastrophic compressor failure.

Both of these features have been around in commercial systems for a long time, but just now coming to residential.  A new residential may have these built in to its control board, if you are lucky.

I've had one of those now for about five years.  Indicator on the thermostat will blink 'Cool' during the cycle, and then come on solid when the compressor starts.  Best 59 dollars I ever spent as it regards to my air conditioner.  I have one that is about 15 years old also and have hit little problem with it (aside from what has happened last month).  R&R guy told me that having the programmable with ASCD can extend the life of a compressor that doesn't use one.

[heironymouspasparagus]

I've had one of those now for about five years.  Indicator on the thermostat will blink 'Cool' during the cycle, and then come on solid when the compressor starts.  Best 59 dollars I ever spent as it regards to my air conditioner.  I have one that is about 15 years old also and have hit little problem with it (aside from what has happened last month).  R&R guy told me that having the programmable with ASCD can extend the life of a compressor that doesn't use one.

Dramatic increase in life!

If it were me (which it is...), I would put a commercial control board set on any decent A/C system I had.  I have the good thermostat, and am thinking about the installation of a control board set on this system as an "experiment" - even though is it not a decent system - 37 years old on its last legs.  Since it is very likely that I will be replacing this in the fall, I may wait and put it on the new one...  Will be able to measure temperatures of all the coils, inside and outside temperatures and humidity, etc.  One that I am familiar with allows some amazing control of the system if the correct hardware is available.  And THAT is the big ugly thing that really irritates - very few residential systems give you the "good" stuff like multiple stages of compression, economizer hardware to bring in outside air (allows what they call "free cooling").  Lots of good stuff out there for commercial - most of it required - that residential doesn't get.  And yes, these things cost extra.  But they pay for themselves in months or a year or two versus decades.

[carltonplace]

My American Standard Allegiance 10 central air unit seems to have a bad contactor or a bad thermostat or both (google research). It hums sometimes and refuses to kick the compressor on. Then the next time it comes on just fine. It does cool. At least once it turned off before reaching the temp set on the thermostat. The unit is a 1997 model that has had some service work but I normally clean it up each year myself.

What should this cost me and does anyone have a contractor they trust? So many cheats out there right now. Thanks.

It sounds like the capacitor is failing. If its only the capacitor that is an easy fix.

[AquaMan]

Thank you so much for the advice. Now I have to make some calls. Good thing it is not as hot today.