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kentbrophy
Jul 20, 2007, 10:40 PM
I have a Carrier 38CKB060300 AC that was installed about 12 years ago.

I am starting to have problems with it: after I turn on AC for a while, from time to time (especially when it's hot) either the circuit breaker is tripped or the fuse is blown. Currently the breaker rating is 45 amps, and the fuse rating is 40 amps. What is the rating of the AC - at start-up and at normal operating time? Should I change both the breaker rating and the fuse to 60 Amp rating?

Thanks.

Francis

acetc
Jul 20, 2007, 10:46 PM
They are both undersized, on the name tag of the unit it will tell you what the maximum fuse or breaker should be and that is the correct size you need . If you have trouble after that , I suggest you install a hard start kit on the compressor, (this is a wire in device) two wires very easy. Mike

NorthernHeat
Jul 21, 2007, 10:39 AM
Don't change to a larger breaker. Breakers also protect the wiring from overheating and causing a fire. We don't know what gauge of wire was ran or how long it is.

acetc
Jul 21, 2007, 02:34 PM
NothernHeat is correct in advising you to check the wire size but I am sure that the breaker and fuses that you have are too small for a five ton unit , that is why I told you to look on the name tag of the condensing unit and varify the manufacturers statement of maximum fuse or breaker size, this is on all air conditioning units and when you use something less, then you may have repeated breaker tripping and fuse blowing . This problem is compounded by high ambient temperatures and a dirty condenser.

NorthernHeat
Jul 22, 2007, 12:02 PM
I'm a little concerned about a few things on this post. First of all a 45 amp double pole breaker, is a very rare bird. Usually just find 30-40-50-60 and so on. Electricians usually only install a breaker to protect the wire size he ran, just for an example, 120 foot of 16 gauge wire is only good for 27 amps, so he puts in a 20 amp breaker. The reason is, at the cost of wire he has to choose. What's the purpose of wire, the appropriate gauge wire to run, and then he protects it with the safest amp rated breaker. Why run a 10/2 wire and then hooking it up to a 10 amp breaker?

Also, what's to say? That, originally there was only a 3.5 ton condenser, but someone decided it was to small. So, they put in a 5 ton, without changing the wire from load center.

You can also post this question in the electrical section of helpdesk. But I just wanted to strongly urge you to call in an electrician, before anyone changes to a larger breaker size. One of the first thing I learned doing service work was. You can always put in a smaller breaker in an emergency situation, but if put in a larger breaker, it could get you fired.

All of acetc ideas are very sound advise. There is probably another cause to this problem, since it ran for years without the breaker tripping. An amp reading when the condenser starts and runs will determine if it is the outside unit or a weak breaker, in which case, put in a new 45 amp breaker, if you can find one.

Good luck

bonzai95
Jan 20, 2008, 09:53 AM
I'm a little concerned about a few things on this post. First of all a 45 amp double pole breaker, is a very rare bird. usually just find 30-40-50-60 and so on.

Just to let you know, I'm installing two Geothermal Units with Aux Heat.

On one, the Aux heat requires a 25 amp and a 50 amp breaker while the Geo unit requires a 45 amp breaker.

On the other it's a 50 amp breaker on the heat and 35 amp on the geo unit.

John

NorthernHeat
Jan 20, 2008, 08:59 PM
Just to let you know, I'm installing two Geothermal Units with Aux Heat.

On one, the Aux heat requires a 25 amp and a 50 amp breaker while the Geo unit requires a 45 amp breaker.

On the other it's a 50 amp breaker on the heat and 35 amp on the geo unit.

John


Can you find a 35 double pole or you will have to use a 30

Eric D
Jan 21, 2008, 04:41 AM
I have a Carrier 38CKB060300 AC that was installed about 12 years ago.

I am starting to have problems with it: after I turn on AC for a while, from time to time (especially when it's hot) either the circuit breaker is tripped or the fuse is blown. Currently the breaker rating is 45 amps, and the fuse rating is 40 amps. What is the rating of the AC - at start-up and at normal operating time? Should I change both the breaker rating and the fuse to 60 Amp rating?

Thanks.

Francis

Added Note: Wow! too much coffee this morning....just noted that the original post was from last July! Sorry!
Francis,

DO NOT CHANGE THE BREAKER! Think about this, your unit has worked for about 12 years with the currently installed breakers, correct? Why in the world would you want to change it now? If no one has changed the charge in the unit over the past few months the problem is most likely a dirty coil or system filters causing the compressor load to go up high enough to pop the breaker, as it should work. There is a very slim chance that the breaker has gone bad. If it did, replace with same size, not bigger, but my money is on something is dirty or the blower fan isn't coming up to full speed, or maybe someone has too many registers closed restricting flow.

Let us know what you find,

Eric D:)