Mini-Split unit kicked breaker

DSWalker

David
Corporate Member
Went out to the shop this afternoon and noticed the AC wasn't on. The Pioner mini split had kicked the 30 amp breaker and now I cant get power back on the unit. I don't have a multimeter to check for current. Will try to pick one up tomorrow.

I checked the connections in exterior electrical box and all looked good and tight Then checked the wiring on outside unit. Normal. Interior connection looked good as well. All connections are tight.

Any ideas? Unit is about 3 years old.
 

DSWalker

David
Corporate Member
Ran to Autozone and got a multimeter. 240 going into the external box and zero coming out.

Are these fuses replacable? The fuse is NOT tight at all. It basically just sits there. No current out even if I push it up and down a bit.

I'm assuming this is the root cause.

Hopefully an easy fix. What would cause it to loose its "grip or tight connection"?

Been there for 3 years and no problem to date.
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Oka

Oka
Corporate Member
Those Eaton Disconnects are crap. We installed about 300 and then had to replace them. You really do not need fuses for that unit. You can just you a service disconnect (local breaker or a pull out. I have 4800 AC units going in right now. we just passed the 50% completion point. We swapped to just a local service breaker and no problems since.
 

DSWalker

David
Corporate Member
From my own photos i realized it may be in the wrong direction. Went out and flipped, pushed it in got a tight connection and heard a fairly loud pop at the unit. Kicked the breaker inside again. Maybe there IS a loose wire at the unit?

I'll recheck it in the morning.
 

chris_goris

Chris
Senior User
If you reinstalled the service disconnect and it immediately popped the breaker, I would get an HVAC person in there to determine what the issue is, It sounds like you have a direct power to ground problem somewhere, not a loose wire.
 

Charles Lent

Charley
Corporate Member
I agree. It's not a loose wire. Loose wires do not trip breakers, unless they short out to the case or the other power wiring in the process of coming loose.

You have a problem inside the AC Unit. Time to call the HVAC guy.

Charley
 

junquecol

Bruce
User
Being only three years old, is it still under warranty? If so call whom ever installed it. To me it sounds like the start / run cap is toast. It will probably be a dual value cap, as one side goes to compressor, and other to fan.
 

junquecol

Bruce
User
We swapped to just a local service breaker and no problems since.
Did you use a HVAC rated breaker. We had a HP that needed a 20 amp circuit. Circuit breaker, 20 amps, #12 wire and 20 amp fused disconnect. Never did the fuses blow, but about every couple months, CB would kick out. Because circuit was protected by 20 amp fuses at disconnect, I replaced 20 amp CB with a 30 amp until I could go by supply house and get 20 amp HVAC rated breaker
 

DSWalker

David
Corporate Member
Thanks everyone. I have a couple of calls out looking for a HVAC guy to come and take a look at it.
 

DSWalker

David
Corporate Member
Yes, the inside box has a 30 amp breaker dedicated for the mini split. I do have a couple others in the panel for my 220 outlets.

Suppose I could swap a couple out and do a test.
 

Ecr1

Chuck
Senior User
No need to swap breakers, Check it at disconnect. Pull out the disconnect and put it in the off position. If breaker holds and does not trip you will know that the breaker is good and the wire to the disconnect. If it trips with the disconnect in off position then you have a problem with breaker or wiring to disconnect.
 

Charles Lent

Charley
Corporate Member
Not true. If the 20 amp breaker is weak and trips before it's rating, only a replacement or slightly larger breaker than the one in question will be a good test. We have already determined that the problem is beyond the disconnect switch. Opening the circuit at the disconnect will only prove that the breaker holds with no load at all.

Swap the breaker out to the 30. If the unit runs and you can measure the current (amperes) being drawn, you will know if the original breaker should hold or not by the operating load amperes. If you can't measure it, just get a new 20 amp breaker and put it in. They aren't that expensive. My bet is that it will hold fine and the original has just gone weak. Don't leave the 30 amp breaker in this position. A short circuit later might cause a fire with a "too large" breaker installed. The original 20 held fine for 3 years, so you shouldn't need a larger breaker than 20 amps. Of course, measuring the actual ampere load is the best way. Your HVAC guy can do this with a clamp-on ammeter,, but a multi meter cannot measure amperes this high. An electrician would be the alternative if you want somebody who is capable of measuring it. I would do it if you were closer to me, but I'm too far away to do it easily. I'm a retired EE with 60 years experience at this.

Charley
.
 

tvrgeek

tvrgeek
User
Hate to be a little harsh here, but between safety and codes, if you have to ask, you really should wait for a professional.
Clamp on meters can't see start surges. Lose disconnects are a fire waiting to happen. Weak breakers do happen, but are rare unless used like a switch. A pop is always a very bad noise.
 

Gotcha6

Dennis
Corporate Member
When the A/C tech gets there, he should look at the nameplate load specs and see what is says should be your MOCP (maximum overcurrent protection). He will let you know what size breaker you should have from that. He may not be licensed to change it, but he can tell you if you need to.
 

DSWalker

David
Corporate Member
Main mother board is likely fried. Found a couple spots showing burns. Bummer. Searching for replacement.
 

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