Compressor does not cycle

[markc]

I have had a this Vendolator VF117B (square top from the 60's)  for about 20 years.  got it free.   several years ago I unplugged it, to save electricity and also could not afford to keep it stocked, it was free vend and my friends drank alot but never seemed to bring their own.  At this time the beers would come out very cold, when you would open a bottle it would ice up in the neck.   about 6 month ago I decided I wanted to start using again,  when I plugged it in I noticed the compressor fan did not work.  So with the help from SodaJerks  I ordered new motors for both the compressor and evaporator,  I removed the deck so I could cleanup everything,  while I was replacing the evaporator fan, I decided to go ahead and disassemble and clean/repaint the evaporator parts, not the evaporator just the metal that forms the box.

I also had to replace a contactor see here: http://soda-machines.com/discussions/index.php/topic,15436.0.html

Its all back together, full of product but compressor does not cycle.

I have a thermostat in the air flow coming from the evaporator,  the air temperature will get down to  about 33-34 degrees.   The door seal looks good,  there is some condensation but not much, and actually the thermostat also checks humidity, says 48%.   Drinks are cold but not icy.

The fan shroud on compressor was destroyed, hoping that maybe that was the issue I put a fan in front of the Pepsi machine to see if the increased air flow would help, but no luck. (not sure if that is a valid way to test that)

I am also wondering if by taking apart the evaporator I could have change something, specifically the metal part that is the shroud for the evaporator,  i could not remember which way to put it in, so i guessed, it fit and air flow feels pretty good.

also I have the original thermostat on the unit.

so what you think?
1) I need a shroud
2) I put evaporator together wrong
3) it just low on freon?  

Thanks for any help

[MrMark]

I'll itemize my thoughts -

1) Are all the door gaskets good and doors closing tightly?
2) Is this the original compressor deck and compressor?
3) R-12?
4) When you ran the fan test, did you place the fan to insure the air that was heated by the condenser was pulled away and discharged out of the area? (I don't think it's your problem, but curious)
5) Did you notice any of the steel refrigerant lines having accumulations of rust, particularly the smaller hot gas line coming from the compressor to the condenser? And or those same lines being wet looking, like a light coating of oil, either at the brazed joint to the compressor or the lines/condenser?
6) What is the ambient temperature the box sitting in as it get's to the middle of the day? Is the garage vented or cooled in any way?

[markc]

1) Are all the door gaskets good and doors closing tightly?

 the gaskets on the bottle door and main door look good.  they are pliable and clean.   the only thing I have seen to test the door seal is to put a light inside the machine and see if light can be seen.  I have done this and cannot see light.

2) Is this the original compressor deck and compressor?
   yes
3) R-12?
    yes,  i assume.  machine is from 60's and there are no ports to fill the system

4) When you ran the fan test, did you place the fan to insure the air that was heated by the condenser was pulled away and discharged out of the area? (I don't think it's your problem, but curious)
   I tried the fan 2 ways,   one, I put the fan behind the machine and faced the fan so it would pull the air out off machine.  two,  placed the fan in front of the machine and and blew the air into the compressor
 
5) Did you notice any of the steel refrigerant lines having accumulations of rust, particularly the smaller hot gas line coming from the compressor to the condenser? And or those same lines being wet looking, like a light coating of oil, either at the brazed joint to the compressor or the lines/condenser?

no, unit was very dirty,  its all cleaned up now,  there was a couple of small rust spots but not significant. 

6) What is the ambient temperature the box sitting in as it get's to the middle of the day? Is the garage vented or cooled in any way?

its in air conditioned basement.  about 74 degrees.



I went ahead and took apart the evaporator again.  turned around a part (evaporator picture will show which part), and also fabricated a shroud based on some pictures found in the forums. 
after this the temperature got down to 32 degrees,  I let it run for several hours but it did not cycle.

[markc]

picture 1 of shroud

[markc]

picture 2 of shroud

[briandr1]

Bad thermosteat? have you kinda tapped it with a screw driver hadnle to see it the contacts are sticking on the thermostat? Sometimes a slight tap will cause the contacts to release. Worth a try considering the tstat is what supplies power to the compressor.

[markc]

I will give it a shot.  I assumed the cutoff on the thermostat was less than 32 degrees.   also, since the compressor never kicks off, I would expect the drinks to be frozen.

[briandr1]

I would figure if the compressor ran too long the thermal overload would trip when it got to hot. Does it have any frost build up when ir runs a while

[MrMark]

These units are all sealed systems. There will be a nameplate on both the compressor deck, and the box itself, indicating refrigerant and charge. But it's probably R-12.

Since the box is in a 74 degree ambient, and it's not getting as cold as it once did, I am thinking it has lost some charge. The stat not opening is a good thought, but if the unit isn't getting to temp as evidenced by the bottles not getting as cold as they once did, and door gaskets are apparently good, and there does not appear an additional heat load than what it had in the past, that the unit has lost capacity. Lost capacity due to lost charge (likely), or compressor inefficiency (unlikely).

R-12 tends to leak before the other refrigerants do due to it's smaller molecular size. Oil accumulated on one of the lines is usually an indicator, but not always, especially if it's a miniscule suction side leak. And the leak can be so minuscule that it is virtually undetectable with sniffers or soap bubbles.

Sounds like you need to find someone who knows how to work on these boxes. A clamp on type of tap can get access to the system to add charge, but leaving it on there becomes a leak. So, the unit needs to be tapped, the charge recovered, remove the tap and fill the hole, change the drier, solder in a new service tap line (in place of the pinched line on the compressor now)' evacuate to 500 microns, and recharge. This is assuming the leak is not sufficient to find, which you will know if you can't pump it down to well less than 500 microns. If you can't pump it down that low, then find and repair the leak.
Once it's all done, pinch off and solder the new tap line as there is no reason the system should need to be accessed again, unless you have another leak or the leak you have get's worse. But by then, availability of R12 will be an issue, and you will have to go through all of the above again anyway.

[markc]

anyone know of a good repair person in central kentucky?

[MrMark]

MarkC,

I know Eric at GlobalCompressors will fix you up. He is on the board throughout the week. I am pretty certain he is in San Marcos, TX (between Austin and San Antonio). I am in Dallas which is not that much better for you in terms of shipping. But since Eric does this for a living, I would go to him, and he can give you an idea of shipping costs and best way to ship. He will probably recommend replacing the compressor as well as the condenser fan motor.

I would call around to some of the local refrigeration places and tell them what you have. Sad part is, this time of year those guy's are real busy, so won't have the time to assess and do the job right, or will charge you out the wazoo to do it.

But we're here to give you guidance, and if you have the metalworking skills you say you have, then brazing or silfosing shouldn't be that much of an issue. You'll only need access to dry nitrogen to use while brazing or silfosing the system back together, and a tap "stinger" for the service port on the compressor. Assuming you've got the leak fixed, then a refrigeration guy will just need to pump down with a vacuum pump, purge, pump down again, purge, pump down then charge.

I might caution you though, if you've broken into the system, you need to plug everything very tightly with rubber plugs. Moisture in the air will seek the dry, dry oil in the compressor and that remaining in the various components which will lead to the ultimate demise of the compressor. That moisture can be vacuumed out with the vacuum pump, but the more there is, the longer it takes. Moisture vapor loves to seek out dry places. If you don' t believe me, think about a box of salt or jar of sugar. 

[markc]

I do appreciate all the advice/guidance this forum offers.    I do not have any skills in metal working or refrigeration, so will need to find someone to do the work.    My kids are flying to San Antonio tomorrow.  Wish I could have them carry the cooling system with them.