My Trane 2 ton central AC has been flawless in the past 8 years.
Last month had it checked out and tech added little freon, working
just fine until yesterday afternoon.
AC was running fine, then tripped its own 30 amp breaker AND the
100 amp main breaker...I reset and 30 seconds later it happened again.
Waited a hour and reset breakers, everything running fine. AC cycles
on and off like usual. After 5 hours of normal running both breakers
trip again..I checked the tightness of all connectors in the breaker box
and the outside disconnect and where they attach to the AC unit outside.
Everything nice and snug, no corrosion, no smoke, no smell, no arc marks.
Just trying to get some idea what the problem might be, maybe a start or
run capacitor on the compressor? Maybe the 20 year old breaker is dying?
I will try to get a clamp on ampmeter to see how many amps the AC is
drawing. I do have the AC company coming out to look at it tommorrow.
Anything suggestions? I was going to post this in the HVAC group but if
your not a pro, they do not want to answer..
Breakers trip for a reason. If both are going it sounds to me like you need
a service call. If you have an amp meter by all means use it and check the
compressor out. Starting current can be 6X of full load amps.
It is possible that the breakers are weak, it happens but only when there is
a lot of tripping. Of course one good fault could be the culprit. But your
also resetting the 100 amp main. So your seeing a lot of current. That puts
my remote troubleshooting viewer, back to the compressor. Sorry I do not
have better news.
Get the opinion of the HVAC company before proceeding. It sounds like
there's a short to ground that's either high resistance or is intermittant.
It's very difficult to give advice over the internet but the company
checking the unit should be able to analyze the compressor/unit to see if
it's causing the trip. As with many mechanical systems, there are many many
Thank you for directing your questions here in the appropriate forum and
most of all thank you for taking the time necessary to determine that this
is the correct forum. :-)
I read this, and...
All I can say is turn it off, leave it off, and wait until the AC company
Your problem screams of a bad compressor, and if its tripping the main, you
dont want to consider what it might be doing to the line from the breaker
box to the unit in the meantime...
You are probably right but I had a similar case and could not get anyone
look at it for several days so I decided to take a chance and change the
breaker and it turned out the HVAC was fine and it was a bad breaker. I
asked all the HVAC guys and they told me changing the breaker would be a
waste of my time. Guess I was lucky for once.
AC man will be here in the AM to check
it out. I did have access to a clamp on
ampmeter and while running the AC
pulled a steady 8 amps. Cycled on an
off several times in two hours, then
both breakers tripped again. Odd thing
was the AC was not running or trying
to startup...Wondering if the problem
is at the power pole. My wires are
rubbing against the metal guy wire
to the ground and I guess the last
power co tech just wrapped electrical
tape around them for insulation, wonder
if it has worn thru and when the wind
blows makes contact and blows my
breakers...Will have the power co
out in the AM also!
HVAC man arrived right on time at 8am.
He went to the outside unit took off the
electrical cover hooked up his ampmeter
and in 30 seconds if failed. Turned out it
was the wire from the disconnect box to
the AC unit itself, two wires were chafing
from the vibration of the AC running.
This occured over 20 years..BTW.
We could see where a little water had gotten in and thats were the short was.
Insulation was worn away and you could see where it was arcing..New heavy
flexible stranded wires fixed it right up!
Thanks for all the suggestions/help!
The OP said its taking out both the branch and main breakers. The odds
of both breakers failing simultaneously is low. A weak branch circuit
braker might trip, but if the 100A main breaker is tripping along with
it, something is seriously wrong.
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