crazy compressor

[slapshot]

Went out on a call today on a walk-in cooler, 1hp remote condenser outside, flooded, oroi valve, pumpdown...you get the picture.
Stat was calling, condenser fan was running, compressor wasn't.
Checked top of the head, hot, but not excessively hot, amp draw, 35amps, almost LRA (41). Overload not opening. Shut power off let it cool a bit, return power, it starts, still high amps, but slowly drops to RLA, 5.5 and cools down, no problem. It's a cap start, cap run compressor I figured the potential relay contacts were sticking open, and the unit was trying to start on the run winding. I replaced the electrics for now, anyone ever see this before?

[Dowadudda]

cmon dude. how can anyone possibly help you? Think about this a second, and I am not being mean either. I want to help you as much as you want the better answer to your question.

But how can I help? I don't know jack. Whats suction, what's dicsharge, superheat, subcooling, ambinent in and out of box, ??????. I could go on and on. Tell me what the eff it's doing, then I will help. take those measurements. Come back and talk to me.

Here is the thing. The only way your gonna do better at guessing, is simply learning.

[hillbilly tech]

There is usually something else causing the promblem than the starting ,run cap.,relay.When compressor is struggling to start or run usually gets the start package.

[slapshot]

sorry...
R134a, tx valve, 125psi head, 10f s/c
22-25psi suc, 20f s/h
box temp around 38-40f
ambient 38f
tight sight glass, ref. system seems to be fine, my question was more directed at the electrics and if anyone ever saw a potential relay behave this way?

[R12rules]

here's a whole string of sugestions:

check your compressor terminals to ground.
Check the amps on your start winding while in operation. make sure your run cap is working. verify the capthat is in there now IS the recomended one.

I assume you carry the two electrical handbooks by Copeland and Tecumseh.
These books have all the data you require.

check for other units experiencing problems. an electrical brownout will bring down a run cap in short order.

look for lose connections.

replace the start relay if she wont do the job.

does the suction line show signs of regular fllodback, icing up?
if so, you could have yourself a system which is flodding your comprssor during startup.


have fun

[k-fridge]

Would the comp restart under load before replacing the start components? Could be the start components but hard to say now. Yes I have seen them act that way with a bad relay, will act more like a PSC A/C compressor trying to start under load.

Could also be a flooded cylinder keeping it from starting untill you boiled the liquid out of the jugs. Better check the superheat, crankcase heater, soleniod, and the LP switch setting.

Also check all the connection stem to stern to be sure you're not dropping a leg to ground or getting a voltage drop. Yu mentioned you checked the temp on top of the head, sound like a Copelemetic. Are you sure it's not a dedicated 240 comp running on 208? I see it too often and they don't like to run right, especially if the voltage drops a little further. I have also see the wires from the comp to the start pack bad where one will become intermittent and cause this.

[slapshot]

Thanks for the replies guys...
R-12...I verified with a Tecumseh dealer that all parts were correct, compressor is only 1.5 years old. I replaced start cap, pot.relay, and overload with factory authorized parts.
No signs of floodback as it is a pumpdown system, low press switch opens at 5psi and closes at 20psi, replaced that too two months ago on an unrelated call.
k_fridge...Yes the comp would start under load before parts were replaced, every time.
You got me thinking, maybe the solenoid is leaking by during an extended off cycle, say overnight when no one is opening the door, and flooding the compressor. I did check all the wires for tightness when I was done.

I hope it's just bad electrics...I'll keep you guys posted.

[matt8085]

Originally posted by slapshot
Thanks for the replies guys...
R-12...I verified with a Tecumseh dealer that all parts were correct, compressor is only 1.5 years old. I replaced start cap, pot.relay, and overload with factory authorized parts.
No signs of floodback as it is a pumpdown system, low press switch opens at 5psi and closes at 20psi, replaced that too two months ago on an unrelated call.
k_fridge...Yes the comp would start under load before parts were replaced, every time.
You got me thinking, maybe the solenoid is leaking by during an extended off cycle, say overnight when no one is opening the door, and flooding the compressor. I did check all the wires for tightness when I was done.

I hope it's just bad electrics...I'll keep you guys posted.

LLS leaking by would just short cycle the compressor on LP, not flood the comp. Unless it's getting hung wide open, but in that case you would have a much colder box temp. Customer would be comming in to frozen product.
I had a compressor (CSCR) once that would not start under a load, even after the start components were replaced. The LLS would open on T-stat, suction would come up, LP close and it would go off on OL. Not untill suction came up substantially would the compressor start. Just like K-Fridge said, this motor had mysteriously morphed into a PSC. End result? Turn to turn short in start winding, just enough to cause a headache. Changed comp.

[slapshot]

matt...yup your right, i realized that this morning while mulling it over during our coffee break. Thanks for the input, I did prepare the customer for the worst, so we will wait and see.