Cavalier cs-96 compressor resistance

[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)