Capacitor question

Wayco Wayne_2

working some long hours this week since we've had only 2 Summer days everybody has called all at once. Had a job where the running capacitor was blown for the compressor on a 3 ton residential Heat Pump unit. Went and got a new one and installed it. The first time I turned it on there was a strange intermitant pulsing for the first minute after start up. It then settled down and ran OK. The 2nd time I started it up a before I was to pack up and go. A hole blew out of the bottom of the new capacitor. I'm pretty sure it's wired correctly. Since it was Sat. and late the supply houses were closed. I'll be going back tomorrow. What could be going on???? I may add a hard start kit, but I'm not sure that will help. Me thinks it may be inside the compressor, the problem that is.

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Ray M_2

start cap

It sounds like the potenial relay is hanging up keeping the start cap in the circut.

Ray m

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Wayco Wayne

There

is no start cap. WW

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David_5

Compressor

You need to check the resistance of the compressor windings to see if they check Ok. run to common should be lowest reading. Start to common higher reading. Run to start the highest reading. Adding run to common reading with start to common reading should equal start to run reading. Also measure resistance to ground from each compressor terminal with meter at the hghest setting. Any reading to ground means grounded compressor = NG. If those readings are ok check running amps on compressor and voltage. Do not run compressor with terminal cover off, the glass plug could blow out if there is a problem with compressor. The run capacitor should be wired in series with the start winding. Don't assume it is wired right. Also make sure all wire connections are clean.

David

Tony_8

sounds like

the winding insulation is breaking down. Sometimes they need to "warm up" before they do "their thing". An old fashioned mega-ohm meter might help. Not many do that anymore. Only time I ever had a cap of any type blow a hole like that, it was grounded. Only seen it twice in 20 yrs. Have fun !

Wayco Wayne

Thanks guys

It was hard to think out there when it happened. I was tired and had to pee. The HO had left and locked the house. I had just replaced the indoor blower motor and had 2 more calls to finish a full Saterday waiting for me. When it blew I just packed up and said to heck with it. I am suspecting the windings too. I had a megohm meter once upon a time but used it so infrequently I don't know where it is. If I figure it out tomorrow I'l report in. WW

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D lux_2

2nd that wiring could be wrong

Make sure the voltage is right could need 440 v cap whats the volts comming in yhe unit running and not ? amps ok ?

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MikeB34

Start winding

There may not be a start cap, but the start winding still need to be out of the circuit after start up. Sounds to me like they're staying in, and the resulting amp draw is blowing you cap. either way, its a new compressor.

Wayco Wayne

Today

I went back with a new additude. I checked the compressor for grond using the regular ohms scale. No ground I then checked it using the K ohms scale. No ground. I then used it on the M ohms scale. I got numbers that started at 12 and then doubled and rose several more times until the meter read no ground. I then switched leads and the same thing happened. Do I have a high resistance ground or what? I did it with another meter and it did the same thing. Please explain to me what's going on.

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Don_4

sounds like you have a shorted coil with a poor connection to ground. Did you do the ohms check on the coils as some else specified??

hope

Have

you try another capacitor?/ I see them blown all the time.
You know what they say,nothing made to last now days.
If the start winding was staying in the circuit it would
just go out on overload and a very short time.
As mention above the insulation valve need to be check with an megohmmeter.
New hermetic motors have resistance value of more than one
hundred megohms.If you have reading of fifty or less then most likely the insulation value is deteriorating.
Smell the refrigerant,if its been severely overloaded you
can tell by the smell. Also moisture in the system will give you low ohm reading to ground and you are most likely reading contaminants in the oil.This is why it is so important not to add freon to a system that as a leak.
Its the domino effects. Whats the history with this equipment? Then again it could be just a cheap made capacitor off the self.

Glenn Harrison

Definetly have a short.

Wayne, you have a high resistance Megohm short to ground. This means that the insulation on the windings has broken down severly. The compressor is shot, and needs to be replaced, also with new refrigerant and oversized liquid and suction line filter driers, as the current refrigerant is high in acid and mositure content. Otherwise replace the system if it's more than 10 years old. You will be doing them a favor.