Ruud outdoor unit not working- contactor?


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Old 04-30-16, 03:05 PM
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Ruud outdoor unit not working- contactor?

I have a Rhudd Jamb-024jaz outside unit that is not turning on. Thermostat inside works and I get air out of the vents but the outside fan doesn't turn on I hear no clicking or humming either. From what I've read I'm assuming it's the contactor since the fan isn't turning on (spins freely manually) and I don't hear humming. Is that a good guess? If so does any single pole contactor work and...Is it a single pole contactor? I can't find a part number anywhere.

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Last edited by PJmax; 05-01-16 at 08:39 AM. Reason: added pic from link
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Old 04-30-16, 04:26 PM
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There are a couple of things you can try. If you have a multimeter, set it to AC volts and measure between the Yellow & Brown wires on the right side of the contactor. With the thermostat calling for cooling, you should measure 24VAC. If you measure ~24VAC but the outside unit isn't running, take a piece of wood or plastic and push in on the "button" in the center of the contactor. This will manually close the contactor. If the outside unit turns on, then the contactor is probably bad.

If you have a multimeter, you can determine whether the contactor is a single or double pole unit. Set the multimeter to the lowest ohms scale. Turn off the power to the outside unit (there should be an electrical disconnect near the outside unit). Disconnect the heavy Black & Red wires from the top terminals of the contactor. Put the ohmeter leads between the top & bottom terminals on the left side, then do the same on the right side terminals (thermostat not calling for cooling). If you measure an open circuit on both sides, it's a double pole contactor. If one side measure ~0 ohms while the other side measures open, it's a single pole contactor.
 
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Old 05-01-16, 05:55 AM
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When I push in the contactor, the compressor turns on but not the fan. Any other things I can try without a multimeter or would it be best to replace the capacitor and contactor since they're the cheapest parts?
 
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Old 05-01-16, 06:21 AM
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I can get everything to run but have to first hold down the contactor, then kick start the fan with a stick. Replace both?
 
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Old 05-01-16, 06:44 AM
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A classic symptom of a bad fan capacitor is that you have to push it to get it started and then it will run. So, it would appear that your fan capacitor is bad and needs replacing. As for the contactor, it's up to you whether to replace it or buy a multimeter to do some basic testing. If you have a Harbor Freight store near you, they have a basic multimeter for
 
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Old 05-01-16, 07:55 AM
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My capacitor is a 35/3uf 370vac 50-60Hz Would a 35/5 if 370Vac work? Or is the uf the thing that matters? (I can get the latter today via Amazon otherwise I'll wait for tomorrow when my ac supply opens). Thanks for all your help, a multimeter is on my list to get just haven't gotten around to it...guess this is as good a reason as any especially if I can't get a capacitor today.
 
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Old 05-01-16, 08:37 AM
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Your 35/3 mfd capacitor is what is referred to as a dual capacitor. The 35 is used for the compressor and the 3 for the fan. The important thing is for the capacitance value to be matched. As long as the voltage rating is equal or higher to the original, your okay. It's hard to say whether the 5mfd fan cap would work satisfactorily or not. While it's only 2mfd difference, it's almost double the original value. I'd suggest that you get the exact value.
 
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Old 05-01-16, 08:44 AM
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You've got other problems then the capacitor. The contactor not closing has nothing to do with the cap.

You need to check for 24vac where the thermostat wiring connects to the condensor unit. You need to verify 24vac to the unit. If you do have the voltage outside... you may be low on refrigerant.

I agree on the cap sizing.... the motor was designed to specifically designed to work with the stated size.
 
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Old 05-01-16, 01:21 PM
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I checked voltage between yellow and brown wires....it was 0 even though the thermostat should have been calling for cooling and the attic blower was going. Did I need to push the contactor in? I assume next place to check is coming out of the thermostat?
 
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Old 05-01-16, 01:24 PM
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Ok.... now check it where I told you to check it.... where the wire comes from inside the house and connects to the unit. There will usually be wire nuts there.
 
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Old 05-01-16, 01:27 PM
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I had a suspicion that you would find 0 volts at the contactor coil. The next place to check for voltage is where the control voltage (24VAC) comes into the outside unit. There will be wire nuts connecting the line from the house to the outside unit. If you have 24VAC at the wire nuts (where it comes into the unit), but not at the contactor, the most likely cause is low refrigerant. Many systems have a low pressure switch in series with the 24VAC going to the contactor. If the pressure drops too low (usually caused by being low on refrigerant), the switch opens, preventing the compressor from running. Running the compressor when it's low on refrigerant will damage the compressor.
 
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Old 05-01-16, 01:53 PM
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I'm going to apologize for my probable stupidity....i previously put one lead on the brown wire at the contactor and the other on the yellow wire at the contactor and measured 0 VAC. However when I put a lead on a ground and measure the yellow it's 24VAC then measure the brown with ground it's also 24VAC. Should i still look at the wires coming out the house before the compressor?
 
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Old 05-01-16, 01:56 PM
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Yes.... you need to check the wires where we described.

You are describing an ok contactor coil and an open Common wire.
 
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Old 05-01-16, 02:09 PM
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Yes 24 VAC come out of house
 
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Old 05-01-16, 02:11 PM
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Then, most likely, the low pressure switch is open due to low refrigerant.
 
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Old 05-01-16, 02:22 PM
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Thanks, I appreciate all the help on this. I'll give someone a call. While I was closing everything up I found a "high pressure control waypoint reset button". After pressing this button the contactor immediately closed and the compressor started to hum. Fan did not turn on though so I used a pencil to get it going. Unit has been running for an hour now with no issues. I've checked in the attic and at the compressor and the lines have no ice on them.

It sounds like maybe the capacitor failed and without the fan running the temp/pressure rose and triggered the high pressure switch. Going to try replacing that before the service call.
 

Last edited by runner1510; 05-01-16 at 03:57 PM.
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Old 05-01-16, 03:52 PM
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Ah... good find. Most units don't have the high pressure safety.... just the low pressure.

The high pressure safety tripped because the compressor and condensor weren't being cooled by the fan and the high pressure soared. So it appears you are not low on refrigerant but have just a fan problem.
 
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Old 05-02-16, 04:20 PM
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Picked up a capacitor for $10 at a trane supplier been running great for the past 5 hours. Again I really appreciate the help saved me 10x that from a service call on the weekend.
 
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Old 05-02-16, 05:02 PM
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Glad to hear that you were able to get it running, and for a very reasonable cost.
 
 

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