Summer Starts And So Does The HVAC Trouble

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dacflyer
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Re: Summer Starts And So Does The HVAC Trouble

Post by dacflyer » Wed Apr 14, 2010 4:23 am

most contactors you should be able to manually push the contactor in, but if you want to bypass it, should be ok, the compressor should have a overload switch somewhere on it or in it.
does the unit have a start/run switch or just a start cap ? eitherway, if the compressor is shot, theres not much harm can go worse :P except totally short and trip the breaker.

if you can ,when you bypass the contactor, use a fuse if you can or at least a HD switch to flip it off if need be,. most outdoor units have a service box next to them.
good luck, i am curious to know, but i think the compressor is shot, winding might not be bad, but something internal could be..

oh, i could be wrong also, but i thought that the run windings should be higher resistance than the start winding, because the start winding is what usually give the compressor the hard kick it needs to get going. and then the run winding just keeps the momentum going..
good luck :)

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Re: Summer Starts And So Does The HVAC Trouble

Post by Lenp » Wed Apr 14, 2010 5:02 am

SETEC
I will assume that the start and run capacitors are ok, and that all connections are tight and the proiper voltage is available. Also I expect that this is a conventional control system and not a microprocessor that is controlling the unit. Years ago I had a York system that used a processor with all sorts of inputs that controlled the system so troubleshooting was more involved.
That being said...
When the unit starts and then stops again if the contactor is still pulled in check to see if voltage is leaving the contactor and going to the compressor. If so suspect a bad compressor or a bad compressor thermal overload control which is usually on the compressor. If it is an overload a ammeter test will be essential to determine if the compressor or the overload is bad. It may be a bad pressure switch but they are usually on the control side of the contactor, not the power side. I guess you could also bypass the overload for a quick test but you will need to watch the system closely for impending trouble.

If there is no voltage to the compressor but the power is coming into the contactor it is obvious the contactor is defective. Bypass it or hold the armature closed for a test and see if the unit runs. If a pressure switch opens it could be a defective pressure switch or a system gas problem, like low charge or high head pressure due to dirty coils or a system restriction. . Here a gauge set and proper knowledge of the system pressures will be necessary to deteremine the problem. If it is a bad pressure switch they are inexpensive, but, system evacuation and recharging may be necessary to replace it.

Len
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Re: Summer Starts And So Does The HVAC Trouble

Post by SETEC_Astronomy » Wed Apr 14, 2010 6:48 pm

Today the decision maker of the home opted to have a professional out, one we've known for almost 20yrs. According to him the compressor has been in trouble for years. Our particular unit didn't come with a start kit, someone added it when the compressor would no longer start reliably. The compressor was overamping which is what was killing the contactor. Other than sound I don't know how he confirmed this but he said the crank finally broke and is causing the motor to over strain and cut-off. I started getting nervous when the lights would dim in the middle of a cycle on top of dimming on startup. I'm now in the market for a new air conditioner.

Thanks for all the wonderful help and thoughts guys.

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Bob Scott
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Re: Summer Starts And So Does The HVAC Trouble

Post by Bob Scott » Thu Apr 15, 2010 8:31 am

SETEC_Astronomy wrote:I'm now in the market for a new air conditioner.
Do you really have to buy a whole new one and not just a new compressor with top-up of your oil-freon mix?

I'm thinking about how the newer appliances are all computerised and when it does break down, new controller boards are very expensive, if you can still get one 5 years from now.

I intend to keep my older micro-free apliances functioning as long as parts are available. They are simpler to troubleshoot because there is no proprietary software and also built to a more robust standard than the new appliances. (I've been watching the chatter between techs in the appliance repair message bases.)
-=VA7KOR=- My solar system includes Pluto.

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Re: Summer Starts And So Does The HVAC Trouble

Post by SETEC_Astronomy » Thu Apr 15, 2010 8:59 am

Unfortunately it looks that way. The refridgerant our system uses is as of Jan this year a banned substance (well not completely until 2015 or 2020, I forget which). While you can still install and service the units most manufacurers have already stopped production. Unless we can find a no longer manufactured unit in someone's warehouse we have to get a Puron unit. If we get the Puron unit we have to replace our current A-coil as it wasn't designed for the pessures involved in a Puron system (500+psi on a hot day).

I hear you on the microntroller controlled appliances. One component fails and you have to replace the whole board, unless you're a lucky hobbyist and it's not a custom part that failed. The gentleman told me of a unit he installed that uses fiber from the thermostats to the HVAC system. The system utilizes zones, indoor and outdoor temperature and humidity sensors plus a whole host of other things. Point being you set it where you like it once and it factors everything in to provide the same feel day to day. After installation he got an automated call to replace the compressor. When he arrived at the house to find it working he called in to verify an error. No error, the self monitoring system detected 8 current spikes out of range and knew it would fail prematurely.

I love technology and automation but all that really does is give you a better picture of what you can afford to replace... :-/

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Lenp
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Re: Summer Starts And So Does The HVAC Trouble

Post by Lenp » Fri Apr 16, 2010 8:03 am

We replaced a 20 year old York system with a Trane system 3 years ago. Trane offers an extended 10 year parts and labor warranty that is reasonable, and, it is from Trane, not the dealer. You do not need the 'annual checkup' but if the failure is from neglect, it is not covered. Keep the coils clean and the drain free and that's about all that is needed. To get the necessary high efficiencies some sophistication is necessary to fine tune the performance so processors are obvious. Even the old York had a CPU!
Replacing an older system with a non OEM compressor or coil could be dicey since the coil, compressor and air handler must be matched for maximum performance, and, if you don't replace it all, there could be lots of finger-pointing when something doesn't wok right. Freon 12 and 22 is still available, but expensive. Large quantities were stored before the cut off dates for production. Even I have some partial jugs!
Len
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Re: Summer Starts And So Does The HVAC Trouble

Post by SETEC_Astronomy » Fri Apr 16, 2010 10:10 am

Lenp wrote:Replacing an older system with a non OEM compressor or coil could be dicey since the coil, compressor and air handler must be matched for maximum performance, and, if you don't replace it all, there could be lots of finger-pointing when something doesn't wok right. Freon 12 and 22 is still available, but expensive. Large quantities were stored before the cut off dates for production. Even I have some partial jugs!
Len
If I can swing it I'd much rather replace everything. What's here now is a 15yr old system, contractor grade and when you're gutting everything you might as well start fresh. The furnace and blower will likely stay but the coil and outside unit are goners.

Anyone need a starting capacitor? It's new. lol

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Re: Summer Starts And So Does The HVAC Trouble

Post by Robert Reed » Fri Apr 16, 2010 12:19 pm

Anyone need a starting capacitor? It's new. lol
Hang on to it - its your best insurance that your new unit will never need one :grin: .

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CeaSaR
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Re: Summer Starts And So Does The HVAC Trouble

Post by CeaSaR » Fri Apr 16, 2010 12:36 pm

Robert Reed wrote:Hang on to it - its your best insurance that your new unit will never need one :grin: .
Yeah, until you finally either get rid of it or use it in something else. :P

CeaSaR
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Re: Summer Starts And So Does The HVAC Trouble

Post by SETEC_Astronomy » Fri Apr 16, 2010 7:59 pm

Robert Reed wrote:Hang on to it - its your best insurance that your new unit will never need one :grin: .
Good point. Let's face it, we all have a bin full of capacitors anyway, one more can't hurt.

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Re: Summer Starts And So Does The HVAC Trouble

Post by Lenp » Fri Apr 16, 2010 8:06 pm

Maybe use it to start a 3 phase motor on single phase :shock:
Len

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"I must be on the way to success since I already have the junk". (Me)

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