convert R12 to hot shot with r134a comp?

[markvilleman]

Long story short, I got a call: A small walk-in cooler no cooling. Trouble shoot it. the compressor didn't start. the start and run winding are 11 ohms,3 ohms and r to s total 14 ohms. it pull 32 amps which match the LRA on the nameplate then circuit opened by the Klixon overload. Checked capacitor,it's 140uf, (its range should be 145uf to 175 uf.)
It's single phase,1/3 hp,capacitor start,induction run tecumseh compressor. It's nameplate marked with R134a,but someone made a note " R414" on it (don't know R414a or R414b hot shot). The comp was changed half year ago by somebody else. the walk in is more than 20 years and it might be a R-12 system before(info offered by the owner)
My questions are
1.anyone has any good method to check the current relay at this kind of situation?
2.if the guy didn't flush the system, coverted the R12 to hot shot with a R134a comp.will it be damage?( if the old r12 comp didn't burnt out before)

[sgagne199]

to test the current relay couldnt you use a clamp on ammeter and measure amperage thru the start cap. As far as the refrigerants mixing I believe hot shot is compatible with R-12 and 134a

[thefreezerguy]

There are a lot of variables and unknowns.

What I would do for my customer at this point is reclaim the gas, flush the system, replace the compressor, and charge it with 134a. Insure proper superheat after starting it.

[DLZ Dan]

Hot Shot (R-414b) is an HCFC and uses AB, R-134a uses POE.

If he didnt flush the old oil out and put in AB, there may be an issue with oil miscability and having it travel around the system and ultimately back to the compressor.

Sounds like a hack shack repair to me.

[markvilleman]

to test the current relay couldnt you use a clamp on ammeter and measure amperage thru the start cap. As far as the refrigerants mixing I believe hot shot is compatible with R-12 and 134a

Thanks, i would try to test it this way.
About hot shot,what if both type of oil with hot shot in one system,and it still work?

[markvilleman]

There are a lot of variables and unknowns.

What I would do for my customer at this point is reclaim the gas, flush the system, replace the compressor, and charge it with 134a. Insure proper superheat after starting it.

Thanks.

[markvilleman]

Hot Shot (R-414b) is an HCFC and uses AB, R-134a uses POE.

If he didnt flush the old oil out and put in AB, there may be an issue with oil miscability and having it travel around the system and ultimately back to the compressor.

Sounds like a hack shack repair to me.

Thanks.
The owner didn't see the guy doing it. I am thinking if both oil in the system with hot shot, is it the reason the comp get stuck after 6 months.

[2sac]

I would use 414b to replace R12 and any conversions. 134a pump requires POE oil and I would stick with 134a.
I don't know if things have changed ( if they have please enlighten me)but Copeland doesn't reccomend 414b at all for any of their pumps.

[Andy Schoen]

You'll most likely be successful with thefreezerguy's approach.

If you prefer Hot Shot or one of the other R-12 service replacement refrigerants, get an R-12 compressor, e.g., AEA4440AXA if you currently have a high temp 1/3 hp compressor

[btack]

to test the relay I would recommend using a compressor analyzer. as far as the refrigerant issues I hate dealing with conversions done by others because you have know idea if it was done right. If it was originally a R-12 compressor I would drain the oil replace and charge with R-409. 409 works very well in R-12 systems. We put it right on top of 12.

Good luck

[markvilleman]

Update:Flushed the system twice with flush kit and nitrogen. Ordered the same type of r134a comp and replaced it. Changed the filter dryer, added a sight glass.Charged it with R134a. System worked good.
Thanks guys for your good tips.