AC keeps blowing fuses

[jmiller676]

Well we turned our air on recently and the central AC will run with nice cold air for about 15 minutes, then shuts off. I go check the fuse, 15A time delay, and it's blown. I am going to take the cover off the fan outside tonight and make sure it's clean. Any other ideas?

-Yes, this is the right Amperage fuse
-Yes, it was running just fine last summer.
-Yes, it has a new filter.

 

[Mr Evilwrench]

How old is the unit? Compressor could be dying. Make sure the outside coils are clean, good idea to hose them off periodically. With AC, you'll quickly get into needing a professional because the HVAC industry pulled the strings and got the .gov to declare the refrigerants dangerous and you not qualified to work with them.

 

[Crbn79]

If you need help I am an HVAC tech and could run you through a couple of checks.

 

[remauto1187]

Need a clamp on ammeter and a manifold gauge set to measure the lo/hi side. Does fuse blow upon a startup or while compressor is already running?

 

[jmiller676]

Need a clamp on ammeter and a manifold gauge set to measure the lo/hi side. Does fuse blow upon a startup or while compressor is already running?

compressors already running. first thing I am going to do tonight is clean the coil and blow out the fan motor. the outside unit is on the north side of our house which is open to fields. we get a lot of wind so I am hoping it just needs cleaned.

 

[Crbn79]

It could be something as simple as a weak capacitor on an aging compressor (common), dead bug in the contact causing short (very common), restriction within the system (not so common), refrigerant low enough that it's causing the compressor to overheat which increases amp pull (common)

 

[Crbn79]

compressors already running. first thing I am going to do tonight is clean the coil and blow out the fan motor. the outside unit is on the north side of our house which is open to fields. we get a lot of wind so I am hoping it just needs cleaned.

Do you hear the compressor load up (loud mechanical sound) before it pops the breaker?
After re-reading, 15a on a condenser is pretty low. With most fan and compressors running your draw should be right at 15amp.

 

[HoughMade]

....With AC, you'll quickly get into needing a professional because the HVAC industry pulled the strings and got the .gov to declare the refrigerants dangerous and you not qualified to work with them.

Remember back when people thought the ozone layer was going away because of styrofoam at McDonalds, the R-22 at home and the R-12 in our cars? Apparently they solved the ozone issue completely because NO ONE talks about it anymore.....or could it be they found out the thickness of the ozone layer fluctuates no matter what we do?

In any event, you're right about needing a professional to do anything that involves evacuating and recharging the system.

 

[Crbn79]

Remember back when people thought the ozone layer was going away because of styrofoam at McDonalds, the R-22 at home and the R-12 in our cars? Apparently they solved the ozone issue completely because NO ONE talks about it anymore.....or could it be they found out the thickness of the ozone layer fluctuates no matter what we do?

In any event, you're right about needing a professional to do anything that involves evacuating and recharging the system.

Yep! Thing that sucks is someone from the EPA can crucify a tech if they want to. They can pull out the most ancient piece of equipment that isn't even in service any more and ask you to demonstrate. If you fail your certifications can be pulled. That's a worst case scenario though. I've only heard of a couple of guys running into any issues, and it's always been because of failing to properly record R22 use on a paper log. The last case was 22 30lb cans undocumented, which is a big no-no.

 

[Mr Evilwrench]

Took me a while, back in my naive days, to understand why the HVAC companies would jump in on the side that made them look to be at fault, until I realized how much money was to be made manufacturing the replacement equipment, collecting licensing fees, etc. The ozone layer fluctuates with the sunspot cycle, and freon falls on the floor when it leaks. Some people have been so conditioned by this propaganda, I've heard of cases where the customer will back away in sheer terror upon mention of a freon leak. The only refrigerant you'd ever have needed to fear was ammonia, and we haven't used that for a long time.

 

[looney2ns]

Loose wiring connection or bad contactor.

 

[Mark 1911]

Fuses blow due to high line current, which may likely be due to a failing compressor. That is a typical sign of end of life. Is your unit old?

Check the compressor housing (outdoor) for blockages, make sure nothing is interfering with the fan rotation, sometimes critters get in build nests, garbage blows in, whatever.

Hate to sound pessimistic, but they often fail in the spring after sitting all winter long. Not unusual.

 

[dmarsh8]

If I recall correctly mine issue last year was a contactor.
It's a trane XL1200

 

[Crbn79]

If I recall correctly mine issue last year was a contactor.
It's a trane XL1200

Those silverfish/earwigs are horrid, they like the warmth of the contactor. Once it engages it smashes them and can cause a short. Hate those bugs! You know how many 2am calls I've been on cause of them.....

 

[churchmouse]

I bet lunch the Comp. is running and binding up. 15A is a bit low depending on how big the unit is.

 

[scott delaney]

might just be a dirty condencer coil causing high head pressure/high amp draw. worked last year on 16 amp fuse? ....dirty coil.
I would think even an old 2 ton would be more around 18/20, check your unit rating plate for proper amp draw

 

[Crbn79]

I bet lunch the Comp. is running and binding up. 15A is a bit low depending on how big the unit is.

This is why diagnosing over the internet/phone is no good. lol Need someone there checking it.

might just be a dirty condencer coil causing high head pressure/high amp draw. worked last year on 16 amp fuse? ....dirty coil.
I would think even an old 2 ton would be more around 18/20, check your unit rating plate for proper amp draw

Yes, a two ton would be right about about 15 amps. With compressor age it would easily peak above that.

 

[churchmouse]

This is why diagnosing over the internet/phone is no good. lol Need someone there checking it.

I was only betting lunch at white castle.....

If you have coil dirty enough to blow fuses you have pretty much killed the compressor. Not aimed at you Crbn79

 

[Crbn79]

I was only betting lunch at white castle.....

If you have coil dirty enough to blow fuses you have pretty much killed the compressor. Not aimed at you Crbn79

I agree, thermo overload would stop the compressor before you popped fuse. I've seen units matted with dog hair and mud and didn't pop breakers.

 

[churchmouse]

I agree, thermo overload would stop the compressor before you popped fuse. I've seen units matted with dog hair and mud and didn't pop breakers.

But that does shorten the duty cycle of the unit.

OP needs to call someone with the proper tools and get it diagnosed. Most likely DOA