The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Calling all Non-US members!! (Non-US only)
by aussie240
12/07/16 02:39 AM
Photo Upload Tutorial
by DanK
12/06/16 11:35 PM
Sprinklered equipment 26-008
by bigpapa
12/02/16 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
Wow, that was close!
by jraef
11/28/16 07:06 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 13
HotLine1 9
Texas_Ranger 8
sparkyinak 7
Potseal 6
Who's Online
0 registered (), 92 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Page 1 of 2 1 2 >
Topic Options
Rate This Topic
#27329 - 07/10/03 05:43 PM In-Wall A/C Compressor Won't Turn Off
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
I have a through-the-wall air conditioner, 220V, digital settings.

It started misbehaving when I tried to turn it off (by pressing the big red ON/OFF button).

The compressor still runs even though the display indicates that the unit is off.

I pulled the plug immediately--naturally, that shut the compressor. I left the unit unplugged for a few hours and tried again with the same results.

Any ideas as to what is wrong with the thing?

From the little I know about this stuff, if that compressor runs and the rest of the unit doesn't, the compressor will burn out...

Top
Work Gear for Electricians and the Trades

Work Gear for Electricians and the Trades
Work Gear for Electricians and the Trades
Arc Flash Clothing, Gloves, KneePads, Tool Belts, Pouches, Tool Carriers, etc. etc....

#27330 - 07/10/03 06:31 PM Re: In-Wall A/C Compressor Won't Turn Off
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Just at a guess, mate,
I'd say that the Compressor contactor has welded closed, this happens a bit.
Hope this helps.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

Top
#27331 - 07/10/03 06:35 PM Re: In-Wall A/C Compressor Won't Turn Off
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
Ouch...

Top
#27332 - 07/10/03 06:36 PM Re: In-Wall A/C Compressor Won't Turn Off
NJwirenut Offline
Member

Registered: 09/15/01
Posts: 816
Loc: Bergen County, NJ
Definitely sounds like the control device for the compressor has failed in the ON position.

Usually, these are fairly large mechanical relays, subject to the usual contact welding problems, but I have seen one unit which used solid state relays, in which the output device (SCRs or TRIAC) failed by short-circuiting.

Either way, it sounds like you will need to change a relay.

Top
#27333 - 07/10/03 07:17 PM Re: In-Wall A/C Compressor Won't Turn Off
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
The unit was here when we bought the house...there is a second 220V unit that was here (both of these are Carrier brand, no more than 5 years old) that stopped cooling about 2 years ago.

I guess it's time for some more fans

Top
#27334 - 07/11/03 03:21 AM Re: In-Wall A/C Compressor Won't Turn Off
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
ThinkGood,
I work quite often with the Carrier brand of Air Con equipment, if you need a hand fault-finding the unit, let us know! .
The company I work for over here, is a Service Agent for these units and I've fixed HEAPS of them.
That larger unit, you mentioned, sounds like it's lost it's gas (Refrigerant), my guess is there will be a small leak in the system (which is easily repaired!), the main cost would be in re-charging the system.
But, sometimes it can just be cheaper and easier to replace the units, if they are getting on in years.

[This message has been edited by Trumpy (edited 07-11-2003).]
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

Top
#27335 - 07/11/03 04:36 PM Re: In-Wall A/C Compressor Won't Turn Off
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
Could this component be the culprit?

OMRON
G4A-1A
24 VDC
20A 250VA

Top
#27336 - 07/11/03 05:34 PM Re: In-Wall A/C Compressor Won't Turn Off
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
More than likely, mate.
You could try disconnecting it from the unit and bench-testing it, with a 24V PSU.
The contactor should open and close as normal and this can be confirmed by hooking it up to an ohm-meter while applying the 24V to the coil.
If the meter reads a dead short with the supply ON and OFF, the contactor is shot.
I probably shouldn't have to say this, but mark the wiring sequence of the contactor BEFORE you remove the wires, Compressors don't take too kindly to reverse polarity!.
Hope this helps, I would imagine you'd be wanting to get the Air Con running again, I saw on the BBC weather report, last
night that temperatures are certainly getting up there in the US!.

[This message has been edited by Trumpy (edited 07-11-2003).]
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

Top
#27337 - 07/11/03 06:05 PM Re: In-Wall A/C Compressor Won't Turn Off
NJwirenut Offline
Member

Registered: 09/15/01
Posts: 816
Loc: Bergen County, NJ
That definitely sounds like it. Have replaced a lot of those nasty little things in A/Cs and microwaves. Contact welding is the usual failure mode, often evidenced by melting of the plastic case around one or both of the contact terminals.

There should be no continuity between the 2 top terminals unless there is power applied to the coil. If an ohmmeter check shows welded contacts, you can buy a new one for about $6 from Mouser Electronics:
http://www.mouser.com/catalog/613/580.pdf

Your relay is down at the bottom of the page.

Top
#27338 - 07/11/03 07:22 PM Re: In-Wall A/C Compressor Won't Turn Off
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Gidday there Bob,
Since parallel importing started over here, in 2000, I've seen heaps of Contactors and CB's with Brand-names of reputable manufacturers on them, only to turn them over and find something like "Made in Pakistan" on them.
This is just not right!, it's blatant commercial plagiarism and judging by the number of faulty and just plain rubbish products,I've had to replace since then, a real blot on the good name(built up over years) of these manufacturers.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

Top
Page 1 of 2 1 2 >



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals