# Central AC outside compressor buzzing after the coil cleaning? Help!



## Don2222 (Aug 13, 2012)

Hello

My neighbor's central AC 30 amp circuit breaker kept tripping. We checked it and the compressor was working, the line was cold as if there was enough freon but the air blowing out the top did not seem very strong. The FLA - Full Load Voltage is 17 Amps and we measured each of the 240 legs at 15 amps.

So today I went back and the 30 amp breaker in the panel was tripped again. So I got the coil cleaner out and cleaned the coil and put in a brand new Simens 30 Amp breaker. Yes it is a Siemens 200 amp 40 circuit panel. The coils do look cleaner on the inside but it did not seem like the hose spay water was super dirty. See pics(Pic 2 is coils before cleaning and pic 5 is coils after cleaning) *Were they real dirty?*

After doing all this the 30 amp breaker tripped almost right away when it was started up. Sounded like the compressor may have come on for a min.

So I shut the 60 amp breaker off outside and reset the 30 amp breaker back on inside. Then I went outside and turned the 60 amp breaker back on and just heard a buzz. The fan was not moving and the compressor did not turn on!

Please help? I can check and take more pics if needed.


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## heat seeker (Aug 13, 2012)

Sounds like one of the motors is locked/shorted/dead. Can you disconnect one or the other and try again? I'd try disconnecting the compressor first, and see if the fan operates. I tend to think cleaning the coils, while a good idea, will not help in this case. The fan doesn't draw much current; the compressor draws the most. The compressor may be bad, have a bad starting capacitor (if it has one), or is trying to start against head pressure (not too likely).
It might be easiest to remove the top of the condenser and disconnect the fan?
You might have to call in the pro's on this one.
BTW - one of the lines from the compressor should be hot - the one going to the fins. The return line from the evaporator should be cool/cold.
If the compressor runs for a while, then shuts down - is the air handler fan working in the house? If not, that might overload the compressor.


Disclaimer: I am no AC guru, just have a little experience with motors.


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## lukem (Aug 13, 2012)

+1 on the start capacitor, if equipped.


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## blujacket (Aug 13, 2012)

Usually the capacitor's top will be bulged when bad.


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## Don2222 (Aug 13, 2012)

heat seeker said:


> Sounds like one of the motors is locked/shorted/dead. Can you disconnect one or the other and try again? I'd try disconnecting the compressor first, and see if the fan operates. I tend to think cleaning the coils, while a good idea, will not help in this case. The fan doesn't draw much current; the compressor draws the most. The compressor may be bad, have a bad starting capacitor (if it has one), or is trying to start against head pressure (not too likely).
> It might be easiest to remove the top of the condenser and disconnect the fan?
> You might have to call in the pro's on this one.
> BTW - one of the lines from the compressor should be hot - the one going to the fins. The return line from the evaporator should be cool/cold.
> ...


 
Thanks for the tips.
The air handler fan in the house is running fine.
This does have a capacitor that had a label stating it was replaced in 2007.
The compressor lines are not warm or cold because it was not working all weekend. Saturday morning when we tested it, everything was working fine. So it could be the capacitor.
*How do I test this Capacitor? The cap looks ok but you never know?*

See pics
See old round capacitor in upper left of pic 1
Pic 3 - Outside water proof 240 vac circuit breaker and water proof 240 vac outlet.
Pic 4 - Inside 30 Amp breaker that started tripping and started causing this whole problem!


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## blujacket (Aug 13, 2012)

http://www.hvacpartsoutlet.com/troubleshootacapacitor.aspx


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## blujacket (Aug 13, 2012)

Push the contactor in and see if the fans kicks on.


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## Don2222 (Aug 13, 2012)

Hello

Well, I asked an old timer how to check the starting capacitor in the outside condensing unit.

This Lenox Condenser Unit has a:
CMCI25/5DVR
25/5 MFD +/- 5% CBB -65
370/440VAC 50/60Hz
MPP3306370/440J
Protected 10,000AFC
E236128
US C22.2 NO. 190

Since this is a double cap or 2 caps in one.
The Fan uses the 5 MFD Cap
The 240 VAC Compressor uses the 25 MFD Cap
There is one Common Terminal
The terminals are marked
Fan C HERM

So take the leads and use a high ohm scale like 1K
Put the black on C and the red on the other 2 one at a time.
The battery in the ohm meter to power the ohm scale for continuity is enough to charge the cap. This makes the needle go full scale and then the needle will swing back when it discharges. You can also revers the leads to create another charge.
He says if you see the charge/discharge or Bounce as he called it, the capacitor is working correctly.

I tried it and it does seem the cap is working! What next? The contactor?


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## Don2222 (Aug 13, 2012)

blujacket said:


> Push the contactor in and see if the fans kicks on.


 
How do you push the contactor in without getting Zapped with 240vac?


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## blujacket (Aug 13, 2012)

Don2222 said:


> How do you push the contactor in without getting Zapped with 240vac?


 
Use a pencil or a stick


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## Don2222 (Aug 13, 2012)

blujacket said:


> Use a pencil or a stick


 
Is that the 1 small metal tab in the middle on top of the contactor? If so it seems to be already in? WTF?
See yellow arrows in pic below. Click to enlarge


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## blujacket (Aug 13, 2012)

That means it's energized and should be sending 220v to fan and compressor. You have either a bad fan motor or compressor.


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## heat seeker (Aug 13, 2012)

I'd also make sure the motors are really getting 220 volts.


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## Don2222 (Aug 13, 2012)

Hello

Yes, I went up stairs and even though the T-Stat was set for 80 Deg F, I turned the switch to off. Then the contactor in the previous post. (See pic with yellow arrows) turned off!

Then I replaced the Capacitor. PITA. The old one was round and the new one is oblong! See pic

So now when I push in the contactor there is no fan or compressor going! Strange both are not moving?

I disconnected the heavy compressor wires from the contactor and when I pushed it on, there was no buzzing.

Still the Fan did not go on either!

Both the fan and the compressor were working before the weekend and the 30 amp breaker tripping! ! ! PITA
*What is the next step?*


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## blujacket (Aug 13, 2012)

The wall t-stat sends 24v to contactor coil on a call for cooling. That pulls the contacts down to send the 220v to fan and compressor. Next step is to ohm compressor and fan. To trip those breakers, I have to believe the compressor is the culprit.


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## Don2222 (Aug 13, 2012)

blujacket said:


> The wall t-stat sends 24v to contactor coil on a call for cooling. That pulls the contacts down to send the 220v to fan and compressor. Next step is to ohm compressor and fan. To trip those breakers, I have to believe the compressor is the culprit.


 


heat seeker said:


> I'd also make sure the motors are really getting 220 volts.


 
Right on!
Very unlikely that both the Fan and the Compressor would be bad. So when I opened the top again I found the broken purple wire that goes to the common terminal on the capacitor. Bingo!

Reconnected the wire and it all works! The Fan on top now seems alot stronger since the coils have been cleaned. That really makes a difference even though I did not see much come off!

Also cleaned the cold air return with shop vac. See pic 2 below

See yellow arrows pointing to broken purple wire in pic 1 below!

Thanks all for your help!


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## Don2222 (Aug 13, 2012)

Hello

Well 3 things I learned on Central AC servicing!

1. If the AC outside condenser that contains the fan and compressor motor has dirty coils, Then the air coming out the top of the condenser is greatly reduced.
2. If the filter that filters return air is dirty, the volume of air coming out of the cooling register in the house is also reduced.
3. If the evaporator coils inside the house are dirty, Then
The air coming out of the cooling register in the house will not be as cold as it should be!

If any or all of the 3 items above are dirty, then the air conditioner will take much longer to cool the house and can trip the breakers and stop cooling the house!


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## heat seeker (Aug 13, 2012)

Congrats! Glad you got it going.

I would, however, not agree with your statement #1. The outside unit has no bearing on the _amount_ of air moving in the house, but would affect the temperature. The air handler fan (inside the house) moves the air in the house. I totally agree with your other statements. Yeah, picky, I know. 

Now you've got me thinking (and that's dangerous!) that I oughta go out and check my condenser coils for dirt.

Anyway, good work! And you saved your neighbor probably a couple hundred bucks. Hope he springs for some beer, or better yet, pellets for your stove.


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## woodgeek (Aug 13, 2012)

Nice work Don.....w00t.


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## Don2222 (Aug 13, 2012)

woodgeek said:


> Nice work Don.....w00t.


 
Thanks
I just have to go back tomorrow and clean the Evaporator A coil out. Still a little way slow in cooling the house but it does not trip the breaker anymore!


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## heat seeker (Aug 13, 2012)

While you're at the evaporator, don't forget the check the condensate drain/pump.


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## Don2222 (Aug 13, 2012)

heat seeker said:


> While you're at the evaporator, don't forget the check the condensate drain/pump.


 
Thanks, you are right if that gets partially clogged that can be a real issue too.

These video helps


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## Don2222 (Aug 13, 2012)

What is your point pgmr?


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## Don2222 (Aug 13, 2012)

heat seeker said:


> While you're at the evaporator, don't forget the check the condensate drain/pump.


 
Hey Heat Seeker

Is this how you do it with DIYVac?  http://circlepad.com/vac/


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## heat seeker (Aug 13, 2012)

Wow, that's a great idea! I thought my line was plugged a while back, so I just took an air tank and air gun and gave a quick shot of air up the pipe. It wasn't plugged, just had dried the house out enough so water wasn't dripping out as usual.

My unit _should_ never overflow. Code here requires a drip pan under the evaporator with a moisture sensor that shuts the compressor off if it senses moisture in the drip pan. My previous house had a bad installation of the condensate line, so the unit overflowed into the drip pan, and the unit shut down. The bill was over $200 about 8 years ago. I didn't pay, as the unit was still under warranty, and it was a bad install. The drip pan prevented a load of ceiling damage, for sure!

Most of the time, there is a steady, small, stream of condensate coming out, since summer is usually humid here.

I am going to make an adapter for my vac like the one in the video. It makes more sense to suck the crud out instead of blowing it back in!


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## Don2222 (Aug 14, 2012)

heat seeker said:


> Congrats! Glad you got it going.
> 
> I would, however, not agree with your statement #1. The outside unit has no bearing on the _amount_ of air moving in the house, but would affect the temperature. The air handler fan (inside the house) moves the air in the house. I totally agree with your other statements. Yeah, picky, I know.
> 
> ...


 
Thanks, you are right. I fixed my first statement.

Next, I cleaned the Evaporator A Coil with the Evaporator cleaner that does not need rinsing
Also vacuumed the return air filter and vacuumed out the Evaporator and fan housing.
See detail and pics in link below.
https://www.hearth.com/talk/threads/...coil-cleaning-and-orientation-question.88982/

After I cleaned the Evaporator A Coil it is Still not working! 30 Amp breaker in main panel is still tripping.
So I replaced Contactor.
See pics and details in link below.
https://www.hearth.com/talk/threads/...after-cleaning-condeser-and-evaperator.89042/


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