OT - potential relays in HVAC - how important are the ratings?

[GregSY]

I have two 21 year old 5 ton Trane AC units. They use the usual run capacitor, and also a start capacitor which is gated in/out by a potential relay (PR).

The PR is a GE part (3ARR3J4A4) which of course is no longer made. It seem a little unusual in that is is rated for 500v hold - the majority of relays I see now are 400v or less. The drop in is 60-135 volts and the drop out is 240-268 volts. The amp rating is 35 or 50 depending on which reference you choose to believe.

As often happens, the contacts in the PR failed which leaves the cap in the circuit, causing it to blow up. I fixed the unit with a new spare I had bought years ago, but now I need to stock back up for the future.



So my question is....how important are these ratings? If I used a relay that has a lower hold voltage, would it work and work well? Or would it cause some 'issue'?

Also, I see a lot 'kick start' kits being offered that are supposed to solve hard starting issues. I don't think I have that issue, but their attraction is they come with their own PR and using that kit might alleviate the whole PR issue altogether.

Thanks!

 

[Phil in Montana]

Try the lower rated one and see, or go on ebay and wait till one shows up...Phil

 

[deltap]

Look for a cross reference guide. You should be able to get a Mars or other brand to replace that the GE.

 

[GregSY]

I've done that, but the Mars PR does not have ratings that match up - hence my question. I can find a few PR's that have the 500v rating, but they have different drop in/drop out ratings.

Then, there are some 'automatic' PR's sold that claim to automatically tune themselves to the need....sounds a bit fishy but?

I've seen the GE's on Ebay from time to time but they are sometimes scruffy looking or even used.