Author Topic: After power cut, no cold air  (Read 3469 times)

Offline michaeljc70

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After power cut, no cold air
« on: July 14, 2012, 03:41:55 PM »
I accidentally shut off the power at the circuit breaker for my furnace (not condenser) while looking for the circuit for something else. The a/c was on.

After turning the power back on, my a/c was not blowing cold air and the unit outside was not on. I went back to the circuit breaker and the double circuit for the a/c condenser was not all the way to off, but not all the way to on either, like it had been triggered off.

I flipped it to ON and turned the A/c on. The condenser turned on (well, at least the fan on top of it), but no cold air. I also heard a surge every few minutes. I have always heard a surge when first turning the a/c on.

I repeated turning the a/c on/off from the thermostat and still room temp air. Even tried turning it to heat, waiting, turning it back to a/c.

Any ideas? Could cutting the power to the furnace but not the condenser have fried something?

Offline JWWebster

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Re: After power cut, no cold air
« Reply #1 on: July 14, 2012, 05:13:00 PM »
You might have a burnt wire on the compressor. Sometimes a brief interruption can cause a terminal wire to melt. I would check for a fail compressor capacitor. Might be that the fan motr has a sep cap or that the fan side of the cap is ok. Could be a contact on the magnetic contator has been fried.
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Offline haroldsappliance

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Re: After power cut, no cold air
« Reply #2 on: July 14, 2012, 06:34:43 PM »
Time delay could be faulty. Power off and then right back on is not good, hence the time delay component. That is the purpose, as pressure equalizing on the system will allow unit to start with less labor. Locked rotor amperage is four to six times that of running amps. Excess amps are always converted to heat. A loose connection will pull excess amps and could eventually burn and over heat a compressor terminal.

Offline michaeljc70

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Re: After power cut, no cold air
« Reply #3 on: July 14, 2012, 07:31:23 PM »
You might have a burnt wire on the compressor. Sometimes a brief interruption can cause a terminal wire to melt. I would check for a fail compressor capacitor. Might be that the fan motr has a sep cap or that the fan side of the cap is ok. Could be a contact on the magnetic contator has been fried.
My page: https://sites.google.com/site/sublimeappliancerepair/ask-the-sublime-one-a-question/outside-condenser-blues

After looking around on the web, I had actually taken the panel off the a/c unit and inspected the capacitor. It looked surprisingly new (unit is 11 years old). 

One thing that was a little "Burnt" was the thingy in the box on the side of my house. It is a metal electrical box and instead of a pull down handle, it has a cartridge like thing.  I pulled that out and it looked a little burnt and there was a little melted plastic on the box part.  I figured that probably isn't it as the unit has power and as I understand it, it either has power or it doesn't. 


Offline JWWebster

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Re: After power cut, no cold air
« Reply #4 on: July 14, 2012, 07:47:38 PM »
That might be a barrel fuse. Be careful with that.
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Offline michaeljc70

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Re: After power cut, no cold air
« Reply #5 on: July 14, 2012, 07:58:11 PM »
That might be a barrel fuse. Be careful with that.

I looked up barrel fuse. It is something else.  It is rectangular and has a metal bar that pulls up so you can grab it and pull it out.  It appears that it just completes the circuit and there is no fuse or other parts in it.  I think it is just an alternative to the electrical box with the pull down handle to cut the power.
« Last Edit: July 14, 2012, 08:01:03 PM by michaeljc70 »

Offline JWWebster

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Re: After power cut, no cold air
« Reply #6 on: July 14, 2012, 08:08:02 PM »
Got any pictures of it and the unit?

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        never grow rusty.

About the icons: The beer is tip link, if a tech saves ya some money buy em a 6 pack. The small green square=personal message. The green dot is a link to my web page on appliance repair and other general BS I love to post. The letter sends me email.
I love fan letters! LOL

Offline michaeljc70

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Re: After power cut, no cold air
« Reply #7 on: July 14, 2012, 09:14:07 PM »
These should give you a pretty good idea.  It is an Armstrong unit BTW.

I appreciate the help.  I know I most likely need to get someone out.   However, believe it or not, I am having 50 people over tomorrow for a party.  I thought if it is something small I can take care of, it would save me. It is supposed to be 93 here tomorrow.   

I have 2 units. 1 for the lower 2 levels and one for the upper.  I am probably going to blast the upper level tomorrow and hope for the best. 







Offline michaeljc70

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Re: After power cut, no cold air
« Reply #8 on: July 14, 2012, 09:16:29 PM »
After looking at the pics closer, the purple wire looks a little burnt or at least dirty.

Offline JWWebster

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Re: After power cut, no cold air
« Reply #9 on: July 14, 2012, 10:07:39 PM »
Red wire also looks burnt. Did you remove the cover on the compressor and look for burnt wires?
May the hinges of our friendship
        never grow rusty.

About the icons: The beer is tip link, if a tech saves ya some money buy em a 6 pack. The small green square=personal message. The green dot is a link to my web page on appliance repair and other general BS I love to post. The letter sends me email.
I love fan letters! LOL

 

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