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UnionPacific 05-09-2014 11:29 AM

Air Conditioner Issue
Well lets see if we can nail this down.
I have a marine airrrrr 16K heat/cool unit, 3 knob control.
The motor does not even try and start.
If I turn the knob to on, power goes to the motor, I get 117 volts on the one lead. The wires from the cap to the motor, one is melted.
Can I test the cap in a safe way to make sure its working?
Just trying to figure out if its the starting circuit having fried from low voltage, or if maybe the cap just blew.

deniseO30 05-09-2014 02:09 PM

Re: Air Conditioner Issue
UP does it have 3 or 3 terminals on the cap? the start winding is usually yellow.

Some caps have a terminal for "fan" also. usually brown.

Please check inside the compressor terminal cover. the start wire often burns off the fusite pin. If you are very luck it did not short out the run winding giving you a bad compressor.

If the cap is swelled = bad loosely connected terminal on the cap = bad also.
How do you test a capacitor using a multimeter

FarCry 05-09-2014 02:56 PM

Re: Air Conditioner Issue
Isn't your line drawing showing a 240v set up? UP is describing a 120v air conditioning system.

I see you went back and edited your drawing.

UnionPacific 05-09-2014 07:40 PM

Re: Air Conditioner Issue
The cap I have has two lugs. The motor has 3. ! is 120 volt positive power, the other two come from the cap. I have good power at the one not from the cap. the wire is melted from the cap to the motor. I shall check it with the multi now. it is not bulged, but neither was the cap on my generator when it was bad.

UnionPacific 05-09-2014 07:43 PM

Re: Air Conditioner Issue

A cheap multimeter can be used to test if a capacitor is burnt out. Connect one lead of the capacitor to one lead from a resistor (about 50k ohms). Set the multimeter to a high "ohms" setting and place the test leads on the remaining cap and resistor leads. The display should begin at 50 KOhms and then get higher and higher until it reads infinity/overload.

A bad capacitor will either start at infinity/overload or start at 50KOhms and stay there. It won't tell you the ferad rating of the capacitor, but it will give a starting point to troubleshoot.
Is this with the power on or off?

UnionPacific 05-09-2014 07:50 PM

Re: Air Conditioner Issue
with the power off and the meter set to 2K I get .005 and it stays there. bad then correct?

Brewgyver 05-09-2014 07:52 PM

Re: Air Conditioner Issue

Originally Posted by UnionPacific (Post 1825026)
Is this with the power on or off?

Definitely with power OFF. Best with nothing but the meter and resistor connected to the cap. Some multimeters have cap testing ability, but the test described can be done with any ohmmeter.

UnionPacific 05-09-2014 07:53 PM

Re: Air Conditioner Issue
meter and resister connected? what resistor? So I have to unplug it from the motor?

Brewgyver 05-09-2014 08:01 PM

Re: Air Conditioner Issue

Originally Posted by UnionPacific (Post 1825066)
meter and resister connected? what resistor? So I have to unplug it from the motor?

The 50k resistor mentioned in the instructions for testing the cap. Yes, disconnect all leads from the cap. Unless your meter has capacitor testing capability, you have to place the resistor in series with the cap. So, one meter lead to one cap terminal. One lead from the resistor connected to the other cap terminal, and second meter lead connected to other resistor lead.

Brewgyver 05-09-2014 08:06 PM

Re: Air Conditioner Issue
The cap is almost certainly dead, and caps are cheap. Test the compressor windings. With all leads disco'ed, use ohmmeter to check from C to S, and then from C to R. If you have continuity (it will basically be sero ohms), then check from C to the shell of the compressor. That should be open (infinite resistance). If both these are true, your compressor is probably OK. Could be bad mechanically, but that's less common than a burnout. Hope that's the case!

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