Cavalier cs-96 compressor resistance

[Faza]

Hi
I'm making a start on restoring my Cavalier CS 96, I've removed the cooling unit and have it mounted on a platform.
It was purchased not working and wireing was badly perished so hasn't run for a long time.
Testing the compressor resistance with an ohm meter shows common to start 15 ohms common to run winding is 2 ohms. Can I have confirmation on whether the compressor is good or bad? If I'm lookingfor a replacement compressor I'm located in Australia so may be a bit of a search finding a 110volt unit.
Would like to retain the condenser and evaporator as they do seem to be in good condition.
I intend to replace the dryer and both fans .
Picture of compressor info tag is attached.
Cheers
John

[Faza]

Bit of an update, this post by JohnieG seems to be similar , Compressor is a AP4111 Tecumseh 1/4hp.
http://soda-machines.com/discussions/index.php/topic,148.0.html
My 3in1 arrived today so I connected it and plugged it in, compressor kicked in straight away and the capillary tube where it enters the evaporator started to chill after about a minute.
Pretty happy that the original compressor works but the resistances are confusing me, should it be changed out whilst I have the cooling deck on the bench or are the resistances ok?
Cooling deck restore is pretty well stalled until I find out if compressor is ok.
Cheers
John

[johnieG]

Hello & welcome to the site John ...   You quoteing my old post from back in 2002 is making me feel dated!  ( of perhaps more experienced is a better way to think of it)

Well it's good that it cranked over & is chilling anyway,

as I've found out over the many years of doing this hobby, compressor start & Run winding resistances can vary a bit even between seemingly identical compressors of the same model & size/horsepower ( or BTU) ratings, so don't sweat it, if the compressor successfully turns over & runs you're 75% out of the wood so to speak, more importantly is the system charge & running  refrigerant (freon) pressures, of which in your case aren't going to be readily available to read due to the fact that your system is still as originally built with no external service ports visible to use to get a pressure reading out of anyway.  

JohnieG

[Faza]

Johnie thx for the confirmation that all is ok, I'll move on the restoring the deck.
How important is it to change the filter dryer? Is this normally done with these old machines.
Also I need to replace the evaporator and condenser fans, would like to source as much as I can locally in Australia to save on postage, can't seem to find a model/part number of the replacements.

[johnieG]

A good question, & here's a fun fact, your system doesn't have one       ( a filter-dryer)  Vendo didn't seem fit to install them on the majority of the refrigeration decks on these machines they had manufactured, they used a small ( you'd never even know it was there unless you knew what you were looking at) inline fine filter-screen ( some call it a sieve) it's the size and shape of a pencil eraser & inserted into the inner tubing at the tail-end of the condensing coils line right where it seems to change diameter & connect to the capillary tube.   

A new filter-dryer should always be installed when replacing an old compressor with a new unit, or when a sealed refrigeration system is opened for servicing such as a leak repair, etc., however since you aren't replacing your compressor, your service person would have to recover the old freon/R12 & cut open the service line at the high side where it exits the condensing coils & braze one inline, pull the system down to a high (deep) vacuum & recharge the system with the recycled R12 Freon or convert the system over to a more Enviro-frendly gas, ( I'd imagine that Old-stock or Virgin R12 is pricey if even still available down in Oz) it's not complicated to put one in, but it will cost you some coins...

the condensing fan motor is a standard "unit-bearing" type used in HVACR replacement & repair work, yours should be 120Volts AC/50-60Hz 1550 RPM, CW (clock-wise rotation as view from the shaft-end) if you cant find it locally, you might try online at your equivalent of Graingers supply company.  https://www.grainger.com/product/EM-S-Shaded-Pole-Unit-Bearing-Motor-5YJN9?internalSearchTerm=Shaded+Pole+Unit+Bearing+Motor%2C+9+Output+Watts%2C+1550+Nameplate+RPM%2C+115+Voltage%2C+Frame%3A+Non-Standard&suggestConfigId=8&searchBar=true

The evaporator motor is an enclosed "air-over" style 3.3 inch diameter case, single shaft such as a Dayton MODEL 3M538BG 120Vac/1550 Rpm, 1/4" shaft diameter,  such as Garingers model  ( view link)   https://www.grainger.com/product/DAYTON-1-70-HP-3M538?internalSearchTerm=1%2F70+HP%2C+HVAC+Motor%2C+Shaded+Pole%2C+1550+Nameplate+RPM%2C+115+Voltage%2C+Frame+3.3&suggestConfigId=8&searchBar=true     if you aren't sure of the rotation, you can get this motor type in a convertible model, it reverses it rotation by you removing the end-plated & flipping over the armature-shaft core & reassembling the end-plates.  check online for the correct application.

[Faza]

Thx for all the good information Johnie, strange the manual shows a filter dryer I wrongly assumed it was the copper cylinder strapped to the evaporator.
Struggling to find 110volt motors suitable in Australia so I'll look at buying from the site sponsors hope postage isn't a killer.

[johnieG]

The copper cylinder attached to the evaporator is an Accumulator, not a filter/dryer, you normally find the filter/dryer ( which as it name suggests is a water absorbing desiccant media filled copper tube or steel cylinder which also contains a micro-filer screen, or some cheaper models use a perforated screen & glass wool to catch debris)  these are normally located on the "high" side of the system, again typically at the exit port/tube of the condenser coil/radiator assembly were it filters the high-pressure liquid freon to help remove any water vapor that has migrated into the system & prevent it ( the water) from freezing at the tip of the capillary tube & plugging it with Ice crystals & causing an internal blockage,.

They do make suction return line filters/dryers for the low-pressure (vapor) return line, but these aren't normally seen on these smaller vending machines, the low side filter/dryers are more common in automotive AC systems & building HVAC units

an Accumulator is designed to help prevent any still-liquid freon from making its way back to the compressor ( it helps the freon to "boil off" & return to a vapor state) where it could damage the suction valve or piston, it's pretty obvious when this occurred because the large suction line leaving the evaporator & heading down back to the compressor will frost up outside of the bottle compartment down under near the compressor deck. this can be caused by an over-charge system, or a failed or jammed evaporator fan (no air-flow causes the freon not to evaporate completely & it ices up the evap' coils)

The Grainger supply company does ship to Australia, however you'd need to set up an account with them first, they normally don't sell to the general public, more so to companies & contractors, it depends if what your buying has restrictions, I cant imagine electric motors fall into a restricted class, say like cleaning fluids, etc. doesnt hurt to inquire via email to them. 

( I use my job/work account to get me past the bouncer at the door  )
                                                                                                                       

[Faza]

With what I thought was a good working compressor I went ahead with a restore of the cooling deck, rewired it new evaporator and condenser fan as well as a new thermostat.
Started ok with frosting where capillary enters evaporator, have since found out that compressor is sometimes drawing 3 amps and sometimes 10 amps.
Any ideas or is compressor dead.

[johnieG]

don't panic just yet...your compressor may be normal.

the compressor you are using has  a split-wound motor,  internally it has two separate electrical windings, when the compressor is first called to run, the ( appropriately named) start-run relay will first apply current to the "Start" winding, it has a high torque to start the motor spinning against the pressure of the freon in the system, and thus be seen with a higher current draw from the line, now once the motor gets up to speed ( .5-1seconds) the current it draws will cause the Start-run relay to "drop out" the "start" winding & engage the "Run" winding, which will now continue to spin the motor at it's design speed but with a greatly reduced current draw.  the compressor will now run at the lower current draw until the thermostat drops it out when it gets to the cold set-point inside the beverage area until it gets warm enough again to call the compressor to start, and the cycle will repeat.

so when the compressor first turns "ON"  you will see a high current draw momentarily, then it should drop down to its normal "Running" amps, the "START" current reading / difference can be anywhere between 2-10 times greater than the "RUN" current.

however if you have a problem with your start-run relay unit ( loose connection, worn or sticky/tight compressor, an over-charged system with too much back-pressure, or an over-heated system again with too much back-pressure, your relay or your over-current safety device ( some call it the "Clicket" will cause the compressor to attempt to start or re-start over & over again,  this can damage the start-winding & burn it open & then the compressor will be dead ( being that it's unable to start let alone run.  3- amps is around normal running current for a 1/5 HP compressor, yours should have about a 1/4 HP unit & should draw a bit more while running.    but 10 then 3 amps ( start vs run current) doesnt sound that bad to me.

a loose connection, or a damaged start-run relay ( or an oversized replacement start-run like a 3-in-1 booster by supco) can cause many headaches,   using a 1/2 HP unit on a 1/4 HP motor will cause the "start" circuit to not drop-out & cause the motor to "studder"  ( slap itself on & off rapidly)   if you've reused the original start-run relay as I suspect, it may have worn contact points & cause troubles when starting or dropping out once it is supposed to be in the "run" mode... I would replace it with an external 3-in1 unit from Supco ( or similar) they sell one for 1/4 HP/220 Vac


but if the system is running normally & the higher amp draw is only when it first starts, then drops to the lower reading, this is normal

the cooling deck looks great by the way...

[Faza]

Johnie thanks for the reply, I have already installed a 3 in 1 relay as the existing one was trashed.
I might see if I can devise a method of removing the start winding from the circuit when the compressor is up and running to check your theory. (I'm a electrician no refrigeration knowledge though)
I'm using a 240v to 115v step down transformer so have used a 1/3 to 1/4hp 115v 3 in 1 .
Have the 3 in 1 relays been known to be faulty in the past not removing the start winding?
The system seems to start cooling immediately once the compressor kicks in, compressor looks original with no ports to check pressures so I'd assume it hasn't been overcharged, I haven't noticed tell tale signs of a leak but I guess it could be undercharged.
Cheers
John

[Faza]

Quick update, if the unit is left for 5 minutes turned off  and then plugged in and the compressor started it draws just over 3 amps if the compressor turns off then on it draws about 9 amps on the run winding only nothing on the start winding.
Start winding is working as expected momentary current when starting then drops to zero.
If left to sit again for a few minutes turned off the unit once again draws 3 amps when the compressor starts and again just over 9 amps when the thermostat stops and restarts the compressor.
Photo shows how unit is connected
Black common
White start
Red run
Possible gas pressure problem???

[johnieG]

your 3-in-1 is the correct size range for your application, I mean does the compressor not run for very long so the machine doesnt get down to temperature? 

short cycling the compressor isn't very helpful because you're stopping it in the middle of a run cycle then slamming it on again & short-cycling it to your compressors going to see some loading from the back-pressure in the system when it's trying to restart that can cause the overload in the 3-in1 to turn off the motor until it cools down to attempt to restart again

so, from a normal start, how long does it run until the compressor shuts off?

does it run long enough to get down to the thermostat setting?

once it's down to temp & the machine loaded with beverages what you'd be shooting for in an ideal run cycle is about a 60/40 duty cycle  60 % of the time it's off, 40 % of the time it's on ( to maintain the temperature setting)

hard to say what your system pressure is doing, you cant put any gauges onto the system unless you install some clamp-on service valves, I prefer to braze on permenent valves myself, by again this involves recovering the freon & opening the system to cut the lines & braze the valves in place.   add on valaves are handy for diagnoising a system, they can be prone to leaking if installed incorrectly ( say on a dirty/corroded or bent section of line, or selecting the wrong size tubing size adapter,) I polish the lines prior to installed the add on valves to make sure the copper is clean of paint & corrosion for the best seal.

but you can kinda get an idea of how the system charge is doing by observing the evaporators frosting zone & how far up the evaporator tubing rows it goes, with an room temperature of about 70-deg F (20-C) & the evaporator fan running, ( thermostat at max. cold) you should be able to see the first 2 or 3 sets of "Elbows" of the tubing frost up lightly at first, now another test is if you temporarily block the evaporator fan from rotating by gently jamming a rag into the fan blades so the cant turn ( before you turn the machine on obviously) you will now see the frost work its way row by row from the front to the rear of the evaporator coils up into the large copper sausage ( the accumulator we discussed earlier) which should get quite cold & even possibly frost over itself until you remove the jammed fan rag.

so with the evap' fan running you should see 1 or 2 rows frost, if only the tip of the capillary tubing frosts ( think of capillary tube as a piece of hollow copper spaghetti )  ( just where it enters the larger evaporator tube) before the compressor shuts off, or the system runs & runs but doesn't get down to temperature, then you may have an under charge system , which means the ris a slow leak somewhere that needs to be addressed.

or if it seems that the system doesn't run long enough, but the evap' coils seem to be trying to get cold, you may have a bad thermostat, or the wrong type for your machine, (if you've replaced it) , to test for a bad 'Stat ( power off) remove the wires from the rear of the control , temporarily short/jumper them together & insulated them from shorting to the metal chassis & start the compressor & see if it runs longer , it should  run until you unplug the machine, don't leave it this way unattended with drinks inside, unregulated the machine can get down to as cold as 24-degrees F & freeze your bottles to bursting

 

[Faza]

Johnie the cooling deck isn't in the machine once this is finished I'll start on the restore of the fridge itself.
I must admit I haven't let it run for a long period of time, I'm cycling the machine on and off by winding the thermostat down then back up again.
Thermostat is brand new purchased from funtronics.
I'll try it again and monitor the frosting of the evaporator.

[Faza]

Johnie, i placed an enclosure over the evaporator to see if the unit stopped and started without drawing high amps.
With the thermostat turned down the evaporator cooled the enclosure getting down to about 4 deg C.
Box was not insulated and leaking constantly.
As you can see by the picture the evaporator frosted over completely but not the accumulator.
Compressor turned off and after about 5 minutes turned back on without drawing high amps.
Could my issue have been using the thermostat to stop and start the compressor with no off time(deadband) inbetween to allow pressures to settle before restarting.

[johnieG]

Yes,  short cycling the compressor can cause it to stall out when it trying to restart, regardless of the 3-in1 booster ( Note to others: most original OEM compressors didn't come with a start-capacitor to assist with hard-starting, however as its name suggests the 3-in-1 booster does have a start capacitor) the back pressure can be to high to restart itself without a bit of equalization time between attempts.

with all of that frost on your "evap coils would suggest to me that your fan-motor isn't running ( no air-flow will ice over the coils rather quickly)