Probable new AC


  #1  
Old 05-23-10, 09:08 AM
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Probable new AC

I have an older (estimate 10-15 years) AC unit that worked last year, but will not kick on this year. I protected it (plywood over the top), but did not wrap it up. Now it tries to kick on, but kicks off about a second later when I kick the breaker on. The fan then costs to a stop soon. I have a hard tme getting down and behind it to read the plate. - I know it is not new, but it worked well last year, but we only had it on for a week or two each time and it did the job at 95F with humidity.

I have called for service for tomorrow, but know they will try to push for a new unit.

My furnace is a 4 year old Bryant 80%+ two stage with a variable speed fan. Because of the existing number of wires to the thermostat, the the thermostat just calls for heat or cooling and the units does its own management. A 90+ furnace was not a possibility because of the venting problems and the low heating requirements.

We are in a 1400 sf two story "quad home" (4 corner units per two story building) with two interior walls. The exterior walls face north and east. The north wall has a oversized 6' slider and a 36x60 window on each level. The east wall is partially buried 4' (half of the length) with a two 36x60 windows and a steel entry door. Our winter gas heating (furnace and hot water) is nominal ($80/mo maximum for a month or two, and about $15 in the summer) because of the limited exposure even at -30F winters. Our electric bill is less even in hot hot humid summers, even though we keep it on continually because of comfort and more uniform temperatures since we have on open stairway between levels.

If it seems the repair of the old compressor is not practical, what brands of AC should I consider (assuming a high efficiency unit) and what problem could be possible with a new installation? I would probably go for a new thermostat (plus a few extra wires) to get the most out of the system. We use a very big set-back at night and the furnace rarely goes to the second stage for more than 3-5 minutes in the morning rise.

Any opinions are welcome and greatly appreciated.

Dick
 

Last edited by Concretemasonry; 05-23-10 at 10:44 AM.
  #2  
Old 05-23-10, 12:35 PM
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does sound like your compressor has broken down, short to ground, but since ur furnace is only 4 years old, keep it. no need to buy a new one.
 
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Old 05-23-10, 04:28 PM
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ender -

When you "keep it" do you mean the old AC set-up and replace the compressor or take the big step and replace everything including the furnace?

It seems like replacing the "heart" (compressor) would be an option since the system has been adequate in the past. I know an inspection will include a look at the A coil, where many things could be found.

Any ideas on a compressor replacement from a large, multi-location company with all the technicians and overhead? I know I can go the cheap route and find a one man wonder that may do everything properly and cheaper, but I plan to live with this equipment for 10-15 years.

Thanx for your opinion.

Dick
 
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Old 05-23-10, 05:31 PM
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Why not do a voltage test on the compressor per ender's idea it might be bad. And also make sure the 24 volt signal to the contactor is not quitting. And know that full line voltage (240 volts) is getting through the contactor. And that the possible dual cap(acitor) is good.

Now it tries to kick on, but kicks off about a second later when I kick the breaker on.
??? How could it kick on in the first place unless the breaker WERE already on?
 
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Old 05-25-10, 09:13 AM
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A quick up-date on the apparently successful solution -

It was all electrical related.

1. My home has an "energy saver" box to control to power to the unit. At times, it gets no power and I was aware of the quirks and problems with initial start-up and trouble shooting procedures with a variable source. Because of this , I tried several times during the previous day with no success. Apparently, there is a bit of a problem with reliability of some of these boxes according to the technician and my neighbor. He temporarily by-passed it, but will re-connect later if necessary. I should still get the monthly credit unless monitoring catches it, but our power use is very low any way.

2. After getting reliable power, he found a questionably "loose" wire on the thermostat that he reconnected. The old thermostat had been in use the previous two cooling seasons, but ran the fan on continuously during cooling for comfort.

3. Also found a problem with the thermostat and suggested changing it out (he could do it or let me do it). The existing thermostat was the cheapest Honeywell set back version that I did not like because of the location, visibility and non-compatibility with my wife. Since I had already bought a new new Honeywell VisionPro 6000, I had him install it. - Total time 1 hour 15 minute and I found out my old exterior unit as only 8 years old and everything else was clean and proper after things were checked out.

Now it just getting around to setting the programming. I just set it at a decent temp to cool and get rid of the humidity that accumulated (it was 95F+ and very, very humid when it started up).

Thanx for the opinions, but I probably could not have done the trouble shooting myself, including running up and down and inside and out even after the reliable power was available.

Dick
 

Last edited by Concretemasonry; 05-25-10 at 11:05 AM.
 

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