Contactor Replacement (Wiring)

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  #1  
Old 07-24-16, 11:40 PM
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Contactor Replacement (Wiring)

I just replaced my contactor in my condenser. However, I have not turned on the power at the circuit breaker or plug the fuse back in because I need help in the wiring.

I have attached two pictures. In each picture, there are two red rectangles.

https://www.dropbox.com/sh/d1amql3zw...24_190321a.jpg
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https://www.dropbox.com/sh/d1amql3zw...24_193246a.jpg
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The old contactor looks pretty much the same as the new contactor for the exception of two tabs. The old contactor (1st picture) has both tabs on the same side. The new contactor (2nd picture) has a tab on each side.

I plugged all wires back in but got confused when it came to these two tabs. There are black and brown wires attach to one tab while a purple wire attaches to the other tab. Can you check the 2nd picture where the tab is on each side of the contactor and confirm the wiring?

Thanks
 

Last edited by PJmax; 07-25-16 at 09:31 AM. Reason: added pics from links
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Old 07-25-16, 01:52 AM
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The side terminals are the contacts for the coil. When the thermostat calls for cooling, it sends 24VAC to the contactor coil, energizing the electromagnet and pulling the contacts down to complete the circuit and send 240VAC to the compressor & condenser fan. If you have a multimeter, set it to the low ohms scale (power off to both the outside and inside units), and with the brown, black, and purple leads disconnected from the contactor, measure the resistance between the two sets of contacts (where the brown/black and purple wires connect). You should measure similar resistance on both the old and new contactors (I would expect something in the range of 2-10 ohms).

It appears to me that you have the new contactor wired correctly, however the ohmmeter test will confirm it.
 
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Old 07-25-16, 03:00 AM
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Thanks for your reply Bob.

In this video, this person said that those wires (in questioned) can be interchanged between the two terminals. Sorry for calling them "tabs".

https://www.youtube.com/watch?v=keM6kCfOsY8

However, I will check with the instruction that you have provided.
 
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Old 07-25-16, 03:54 AM
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The 24VAC "control voltage" from the thermostat, being AC voltage is "non-polarized", meaning that it doesn't matter whether the brown/black wire goes on the left terminal and the purple on the right or vice versa. However, I would make sure that the brown & black wires are on the same terminal (like the original wiring), whether it is the right or the left terminal.
 
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Old 07-25-16, 04:26 AM
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Thank you for coming to the rescue on this one Bob. I really appreciate the information.

I will update later today or tomorrow.
 
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Old 07-25-16, 09:33 AM
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Looks good.... all ready to fire up.
 
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Old 07-26-16, 09:53 PM
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So, here is an update.

It did not work.

Like the old contactor, if I use a wooden dowel and press on the contacts, then the condenser works. Cool air start to blow inside the house.

Originally Posted by Bob14525
When the thermostat calls for cooling, it sends 24VAC to the contactor coil, energizing the electromagnet and pulling the contacts down to complete the circuit and send 240VAC to the compressor & condenser fan.
Bob, basing on the information that you provided, could the thermostat be defected where it is not sending the 24VAC to the contactor?

Pete, thanks for attaching those images.
 
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Old 07-26-16, 10:16 PM
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There are two wires in a cable that comes from the house. You need to use a voltmeter and check them for 24vac where they connect to the condensor. Check it right at the wirenut connections.

If you have it there..... you have an open safety sensor or time delay module in the condensor.
If you don't have it then you need to check for 24vac on Y and C at the air handler.
 
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Old 07-28-16, 12:54 AM
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Pete, I will check and will provide an update in a few days.
 
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