SMC Discussion Areas

I recently brought this Mills 45 home. The compressor is stuck. I can make it move slightly with a crowbar, but the electric motor won’t turn it.
This is charged with Methyl Chloride. It’s stamped that way on the compressor deck tag as well.
How difficult of a job is it to change over to modern refrigerant, after, of course, getting the old stuff out of there?

Congrats Andy!
Can you determine if the electric motor is locked or is the compressor...?
If the electric motor is the culprit, perhaps the original system functions...

Jim,
That’s a good point.
The electric motor hums and then the overload kicks out. It repeats this about once a minute.
I’ll take the belt off and see what happens. How hard should it be to turn the compressor by hand?

I'm not sure about the force required to rotate the compressor pulley, but think it couldn't be that hard...
It would be nice if the electric motor is the issue. Keep us posted...

Like Jim said, it shouldn’t be too hard to turn the compressor over by hand & you’ll feel more resistance on the compression stroke, although it’s likely to be a little stubborn from sitting, so a careful bit of assistance can be found by gently applying a monkey (pipe) wrench to the compressor’s pulley, use a rag to help prevent marring the pulleys edges, for a “ turn it by hand” test it doesn’t matter which way it rotates, but you’ll have to match the motors rotation once all is said & done.

PS... Fun fact ( sort of) Methyl chloride is the same fluid used in Xmass bubble lights, it’s toxic if absorbed by your skin or vapors , so don’t break open a line or valve in an enclosed area, but I doubt you’re going to be monkeying around with the stuff ( So be aware)

Unfortunately, after I slipped the belt off, the motor runs, a little noisily, but the compressor won’t turn. I didn’t try to force it to break it free if that’s an option, since it’s buried in the machine. I suppose it’ll need to come out to try that. This will entail disassembling the system. Is that as simple as having someone vacuum out the Refrigerant?
I guess the major question would be.... is working with this system something any competent HVAC person can do, or does this particular gas require someone special?
Thanks for your knowledge, guys.

MC ( Methylchloride) also known as refrigerant R-40, is really, really old school. And like Ammonia & Sulfur-dioxide ( found in old 1930’s ‘ fridges, and still used in some commercial systems to date) requires someone certified to handle it (recover the refrigerant)  your average HVAC/R/C guy isn’t equipped to do that.  I’d start looking for an Ammonia certified tech & see if they can handle it or if they know of someone who can.

For those of you who like to be educated...

http://www.c-f-c.com/specgas_products/methyl-chloride.htm

Thank you Johnny. I appreciate the info. I guess That's where I need to start before I do anything else. I might try some more muscle to see if I can convince the compressor to turn, but if I do any restoration work this will need to be addressed first.

Another easy question (I Hope). If the CH3Cl needs to be recovered, can the system then be charged with newer media without problems? (Except changing some parts)

 The methyl chloride/ R40 would have to be recovered ( if the system even has a charge left in it) & thoroughly flushed of any remains of the old oil & crud.

Unless you’re a stickler for form over function ( “originality /vs/ functionality updating the system)  I’d scrap the belt drive & replace it with a modern hermetic compressor & convert it to R134A, although Copeland ( and a few others) still makes a simular type mechanically driven compressor, they may even be able to rebuild the original unit.

The system wil have to be rebuilt according to which compressor goes into the Restoration, I don’t recall if this machine used a capillary tube or some type of expansion valve setup. But it can be done ( converted).

Me personally, I’d scrap the whole lower deck assembly & get a new R134a condensor deck & compressor assembly & splice it to the cleaned & refurbished upper evaporator unit & be done with it. 

Thanks Johnny!
This is a Mills, so originality is requisite.
I now have what I needed to know. Just gotta find the person(s) to do it.
I appreciate the expert advice.

No prob...

Here’s a possible starting point for you...

http://nationalcompressor.com/products-services/open-drive-compressors/

Is the Mills 45 a highly collectible or considered rare machine? I just picked one up as well as a 65.

A bit of an odd spot to ask ( this old refrigeration discussion post) , But yes, I would say they are very desirable and collectable especially if they are completely and in good shape.

Yep what Johnnie said , very collectible

As soon as I can figure out how to resize pics on my phone I'll post some pics of machine es I picked up