Electrical diagnosis of a water source heat pump

Is common reading something to give us 200+ ohms at contactor?. Is contactor coil weak?

I think the coil insulators are damaged.

What is the coil voltage for the contactor installed? I would guess someone put a contactor with a 240v coil.

Not 24v rated coil is it  ac or dc current.   

The coil on that contactor is not 24 volts explaining the higher resistance

The coil on that contactor is not 24 volts explaining the higher resistance

I think you need to check the contactor coil rated voltage.  Is it looking for 24 volts or something higher?  With that high an ohm reading, I think it is looking for a higher voltage to energize.

the answer is in ohms law.

Was the transformer replaced with an inadequate VA output?  Maybe all the component voltages are correct, but not enough current.

Is it a 120V (or another voltage that isn't 24) contactor? They've given us that problem at school a few times. Threw me off like crazy until I figured it out.

120v or 240v coil in contactor.

Had similar years ago, was supplied a 415v coil for 240v application, just chattered in and out, learned to check them before fitting on that job!

Yea its probably that this contactor is rated for a higher voltage but I dont know the resistance seems high to me anyways maybe its burned and there is carbon in between the burns and thats causing the high resistance

Gary,
I really like these "challenge" type videos.  They are making us all think.  You are doing a great service to the trade.  Thanks for what you do.  I for one do appreciate it.  Keep up the good work.

D C coil

Wrong voltage coil.

Wrong coil voltage.

its not a 24 volt contactor

How about the capacitor?

What was wrong with the coil?

the compressor run and common on the contactor may be on the same power supply of contactor.

Remove the contactor, inspect the coil voltage and AC/DC input requirements. It is one of 3 possibilities: Its a high voltage ac coil, a DC coil, or a bad contactor missing the inductor core. Once you eliminate the impossible, whatever remains, however improbable must be the truth.

If you have voltage and coil is good , then wrong/coil voltage.

ohm out the contactor coil windings, check coil voltage

You got a 220 volt coil contactor instead of 24 volts

The meter is showing voltage but actually there is less or no voltage when the circuit is loaded, best way is to place some load like same voltage rating contactor or bulb and test it.
It seems loaded circuit voltage drop problem.

im going to say a failed coil. Think its not letting enough current to flow to pull in the contacts

improper replacement of parts, and you already know the answer ...

idk, was the replacement installed either backward and/or in a hurry?

The coil isn’t a 24v coil?