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Old 05-23-2011, 02:49 PM   #16
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Help with older A/C unit


I thought you meant a breaker outside near the condenser. I have the main breaker between the service and my fuse panel but no protection after the fuse. Like I said...it's an OLD unit. I'll post pics tomorrow too...it'll be good for a laugh.

I'll just grab some fuses tomorrow when the stores are open again (Victoria Day here in Canada).

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Old 05-23-2011, 02:54 PM   #17
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Help with older A/C unit


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I thought you meant a breaker outside near the condenser. I have the main breaker between the service and my fuse panel but no protection after the fuse. Like I said...it's an OLD unit. I'll post pics tomorrow too...it'll be good for a laugh.

I'll just grab some fuses tomorrow when the stores are open again (Victoria Day here in Canada).


































































































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Old 05-23-2011, 02:55 PM   #18
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Help with older A/C unit


Either I'm confused or you're screwin' with me.


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Old 05-23-2011, 02:56 PM   #19
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Help with older A/C unit


You should at least identify the breaker to the outside unit in the service panel and turn it off before replacing those fuses, to be safe.
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Old 05-23-2011, 02:58 PM   #20
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Help with older A/C unit


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Either I'm confused or you're screwin' with me.



I'm messing with you, bro. I was hoping you'd get to work so I could feel like I'm accomplishing some work through you. I'm waiting on a roof top unit to be delivered from another city so I have a few days off.
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Old 05-23-2011, 03:05 PM   #21
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Help with older A/C unit


LOL!!

Service Main shut-off -> fuse panel -> Condenser

The fuse is my only protection on the circuit. It's what I'm trying to say. Not that it matters...


------------------
I'll turn the thermostat off, disconnect the compressor, put in new fuses, turn the thermostat to cool, check to see if fuses blew and/or condenser fan is running.

If fuses are good and/or condenser fan is running = bad compressor and a sad wallet.

Correct?


Edit: you posted before me...glad I provided some lazy afternoon amusement. I promise I'll post back results tommorow so your efforts were not in vain.

Last edited by pete0403; 05-23-2011 at 03:08 PM.
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Old 05-23-2011, 03:09 PM   #22
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Help with older A/C unit


You have a main brekaer and no sub breakers for individual circuits is what you are saying so you'd have to turn the power off to the entire home to tie through at the ac fuse box. Is that it?

If so that is wierd.
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Old 05-23-2011, 03:14 PM   #23
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Help with older A/C unit


Now I can't tell if you're screwing with me or not anymore.

Instead of a breaker panel, I have a fuse panel...individual fuses for each circuit of my house. The two 30A fuses that power my Condenser run from the fuses outside directly to the condensor with no other fuse or breaker.

I didn't think that was weird...maybe different codes here.

Again...if you're screwing with me then

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Old 05-23-2011, 03:30 PM   #24
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Help with older A/C unit


okay, okay, sheesh. be careful at the fuse box when replacing them.

Do that removing the wires from the compressor trick and see what happens, but I have a feeling you're not going to like it. 99.99% of the time if a fuse blows or a breaker trips on condenser the compressor is bad.

And if it is a burn out versus being locked up then you will need new filter driers, both high and low side (refrigerant lines) and make sure the old driers are removed and new ones are not just added in with the old ones still in place. A lot of the times it is the driers themselves that take out compressors as they get clogged so the refrigerant has no where to flow so the compresssor ends up fighting itself to death.

Actually it's good practice to replace driers with every compressor changeout regarldess.
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Old 05-23-2011, 03:39 PM   #25
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Help with older A/C unit


Cool...I'll make sure I tell anyone I get to do the work to replace the driers.

If it is the compressor, I'll probably bite the bullet and get a new unit. Maybe not right away though. The guy told me a new compressor could be $1400 whereas a new unit would be $2500. Seems silly not to go new in that case.
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Old 05-23-2011, 03:45 PM   #26
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Cool...I'll make sure I tell anyone I get to do the work to replace the driers.

If it is the compressor, I'll probably bite the bullet and get a new unit. Maybe not right away though. The guy told me a new compressor could be $1400 whereas a new unit would be $2500. Seems silly not to go new in that case.

Good idea. You'll also have either a five or ten year warranty on a new unit versus one year on just the compressor.
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Old 05-23-2011, 04:43 PM   #27
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Help with older A/C unit


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Hi All,

My AC stopped blowing cold air yesterday. I went out and saw that the fan wasn't on in the condenser and I couldn't hear the compressor.

Pulled out the dryer fuses and put them in the AC slot while the thermostat was calling for AC and they both blew instantly. (In hindsight this was probably dumb)

Called a tech, he says that the compressor windings have probably overheated. He determined this by showing me that the relay was on (there was a buzzing from the 24V and the little contacts were pulled in) and he said that terminals 2 and 3 were shorted to ground.

He did this by scratching off a little paint on the casing of the compressor and touching the terminals with his meter. I saw the meter read 16 (don't know if it was ohms or Mohms) and he said this was basically a short because it was too low.

I have a decent understanding of electricity and I thought an instant blow of the fuses would need a direct 0 resistance short.

I'm probably wrong but the reason I'm a little iffy is the guy instantly tried to pressure me on buying a new unit even though I told him I have a newborn and we wouldn't be doing that this year.

Rather than paying another $85 for a second opinion I was hoping I could describe what he did and get some thought from experts on here.

Thanks a lot!
Wrong procedure. I remove the 3 wires from the compressor then use an ohm meter from the 3 terminals to the COPPER larger line from the compressor. Should have NO continuity or it is shorted. The resistance reading he got may be from paint which he did not scrape thru completely.
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Old 05-24-2011, 12:04 PM   #28
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Help with older A/C unit


Okay, here's what I found today.

Three terminals from the compressor are labeled 1 (bottom side of relay), 2 (capacitor), and 3 (top side of relay).
Resistance:
1 to 2: 3.0 ohms
1 to 3: 980 ohms
2 to 3: 985 ohms

I don't have a microfarad setting on my meter to test the cap.

The other part of my troubleshooting was running the AC without the compressor hooked up:

-Thermostat off
-Disconnected the compressor
-Plugged in fuses (they didn't blow)
-Turned on thermostat and made it call for cool
-Blower turned on, fan was on in the condenser unit (fuses didn't blow)

So it looks like it's the compressor? What do the resistance readings between the terminals tell me?

As a side note: The guy call me back today and says, "I'm missing a 1/4" nut driver, do you have it?" I said No, He says "Because we were using them yesterday outside remember...two of them?" I said I was just out there and there's nothing. Then he said alright in a disbelieving kind of way. LOL, what a...

Here's some pics:

Condenser unit (old as the hills):


Inside:


Cap (looks like it's been replaced?):


Label:


And LOOK! A fuse panel
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Old 05-24-2011, 12:22 PM   #29
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Help with older A/C unit


Thats a 1977 ClimateMaster/Flame Master and is OLDER than the hills. Did you check for continuity from the terminals to the copper line. Unit is not worth repairing if the compressor is shot which it should be at that age. Valves inside will be worn and you will be lucky if it pumps at 85% capacity. 8 SEER or less with that old bird. Fuse panels are going obsolete where I am and some insurance companies I believe are avoiding insuring homes with them from what I hear or may charge a huge surcharge. Not that they are inherently unsafe but people stick larger size fuses in when they have problems and then overheat the wiring and cause fires.
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Last edited by yuri; 05-24-2011 at 12:24 PM.
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Old 05-24-2011, 12:30 PM   #30
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Help with older A/C unit


Crap, I forgot to do that. I have to get ready for work soon so won't have time today. You mean from the terminals to the copper tubing correct?

Does the resistance between the terminals tell you anything? This unit is 3 years older than me!

Oh, and about the fuse thing...when we moved in every position had a 20A or 30A fuse in it...I changed them to the proper sized fises as soon as we got the keys (BTW the inspector missed this)


Last edited by pete0403; 05-24-2011 at 12:32 PM.
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