[UnionPacific]

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]

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]

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]

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]

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]

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

 

[Brewgyver]

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]

meter and resister connected? what resistor? So I have to unplug it from the motor?

 

[Brewgyver]

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]

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!

 

[UnionPacific]

I do not have a resistor. I have however removed the cap, when I put the leads to it now It stays on 1 as if it is not connected.
If I shake it it seems to have liquid in it? should it be fluid? I remember back to distributor days if the coil was bad sometimes it would sound like fluid inside.

 

[Brewgyver]

As I said before, you MUST place a resistor in series to test it with an ohmmeter.

Forget the cap, test the compressor windings. If the compressor is good, you need a new capacitor, new wire leads (with correct ampacity and insulation rating for the load), possibly a new contactor (contacts can be burned or welded). You should also check the power supply wiring to the unit, as undersized wire could have contributed to the problem.

 

[UnionPacific]

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!

ok, C to S, C to R both 0
C to shell, 1 so no connection from case to C.
I made sure by touching both to case and getting 0 then moving one to C and still nothing. So bad cap, right?

 

[UnionPacific]

You should also check the power supply wiring to the unit, as undersized wire could have contributed to the problem.

the wire on the uint itself, both to and from the cap, and to and from the C connection are very small wires. But inside the boat they are all 12 or 14 gauge. The issue was shore power, I had about 3 extention cords from the yacht to the plug. It burned the plug out too.

 

[UnionPacific]

this guy tests a start cap with out a resistor?
https://www.youtube.com/watch?feature=player_detailpage&v=iRt9WYK1wdQ#t=407

 

[deniseO30]

Oh now you tell us! LOL

Anyway.. the wiring is something like this for 120 volt.

Just wish you would give up photos and even actual model number! Most have a wiring diagram somewhere....

If I'm not mistaken the start winding can be with a cap, cap and relay or solid state type. (they use a ceramic resistor in the top of the cap)

 

[UnionPacific]

Oh now you tell us! LOL

Anyway.. the wiring is something like this for 120 volt.

Just wish you would give up photos and even actual model number! Most have a wiring diagram somewhere....

If I'm not mistaken the start winding can be with a cap, cap and relay or solid state type. (they use a ceramic resistor in the top of the cap)

mine is not like that. Both S and R are connected thru the cap.

 

[Brewgyver]

if you have an analog meter, it MAY work, but a digital, forget it. This advice is guaranteed for one million times the fee paid for it.

 

[UnionPacific]

will buy a cap and post the results tomorrow night.

 

[Brewgyver]

mine is not like that. Both S and R are connected thru the cap.

Then the R should be connected to the same terminal as the Line in.