A/C condenser: contactor amp sizing

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Old 05-19-20, 02:23 PM
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A/C condenser: contactor amp sizing

I'm needing to replace a contactor that is ages old. So old, that there no external amp sizing. I do see where a sticker once lived.

Details -
Ground based R-22 unit - probably a 3T
30a circuit breaker
2 pole contactor

Should I buy a 30 amp contactor? 40a?
 
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Old 05-19-20, 05:05 PM
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Welcome to the forums.

30A is fine. 40A is also ok but not necessary.
Some contactors have one switching pole and one shorting bridge.
Some contactors have two actual switching poles.
The amount of switching poles should be matched.
 
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Old 05-19-20, 05:27 PM
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Thanks Pete,

I just noticed this was my first post, my bad for not intro'ing as I joined in. I noticed the account was not fully set up till now. Seems I snoozed on that activation email.

Regardless......

I have ordered the 30a version, I seemed to have failed to note the transformer voltage in the OP (not that it makes a diff here, but does in ordering)

A quick dressing of the contact points quickly diagnosed the issue and solved it short term until the new contactor arrives. I've owned the unit for 30 years and it was new to the house 10 years earlier (yeah, wow), but it seems there was a 3 pole installed and in there now with one pole unused.

Probably TMI, but its cool in the house again. Thats all that counts.
 
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Old 05-19-20, 06:42 PM
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Unless that's a three phase condenser...... the three pole contactor was not factory.
Coil voltage is always 24vAC with A/C contactors.
 
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Old 05-25-20, 07:56 AM
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Thanks for the response. It is a single phase unit. I do recall perhaps from quite some time ago, when this contactor first gave me a hint of trouble, that I could diagnose if one of the bad contacts (in a 3 pole contactor), could be routed to the unused pole when a 2 pole contactor is needed. Thus, somewhere 20 years ago when the OE 2 pole unit failed, it was replaced with a 3 pole unit. We're all back to 2 poles now. Ying and Yang has been restored.
 
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