Problems with compressor running too cold

[abrando1]

I am running Copeland 6TM1 compressors with R408A in Low temperature application. There are two compressors with similar TEV settings but one is running a discharge temp of 90 deg C (good) and the other is running a discharge temperature of 28 deg C (bad). What is going on? The cool running compressor is icing all over the compressor. The condensors of both are 200 psig. Suction of the cold compressor is 0 psig. The warm compressor is ~ 20 in hg vacuum (ideal for this application). How do you under heat a compressor?

[The Viking]

OK,

So what are the subcooling and superheat?

[Grizzly]

I am running Copeland 6TM1 compressors with R408A in Low temperature application. There are two compressors with similar TEV settings but one is running a discharge temp of 90 deg C (good) and the other is running a discharge temperature of 28 deg C (bad). What is going on? The cool running compressor is icing all over the compressor. The condensors of both are 200 psig. Suction of the cold compressor is 0 psig. The warm compressor is ~ 20 in hg vacuum (ideal for this application). How do you under heat a compressor?

Welcome abrando.
I'm with the Viking on this one!
Using the back to basics theory.
The most logical reason is because your compressor has liquid flood-back.
What has or is causing it you need to establish.
Hence the question from viking about the superheat readings.
The subcooling readings are relevant also.
many things can cause this, so check things like,, (in no particular order).
SUPERHEAT AND SUBCOOLING, CORRECT OPERATION OF THE EVAP FAN/S AND IS THE COIL/S CLEAR.
CRANKCASE HEATER.(NOT WORKING- IS COMP COLD UPON STARTUP)
LIQUID LINE SOLENOID VALVE (PASSING).
These are some of the more obvious contributing factors.
But with the little info so far it is hard to pin down what is actually happening.
So most of this is based on educated guesswork!
I hope it helps?
Cheers Grizzlyhttp://www.refrigeration-engineer.com/forums/images/icons/icon14.gif

[hendry]

Hi abrando1,

i learn most compressor has crankcase heater to remove excess refrigerant from harming the compressor.

can you chekc if yours have been fitted?

normally, for such incidents, i'll run my comp with suction valve slightly open [probably 1/4 turn open from full close]. i'll run it until the comp is warm.

Or, some may drain total the compressor's content and charge it fresh oil and resume operation. close monitoring is taken.

hopes that helps.

Hendry, on wesak day holiday.

[powell]

Brrrrrr.........check the compressor superheat.

[paddyaircon]

i think tis no load on evap ?

[Grizzly]

Seems like he has cut and run guys.
I suppose it's to much to hope we would get an answer?
Grizzly

[shyboy]

there is moisture located inside the system, and cause iced block the refrigerant flow through the system. that cause there is no suction pressure reading.

[icecube51]

mostlikely he was stupid enough to overfill the circuit, and coused the compressor to chouke on liquid. now he is so embarrest to come forward whit it,whe will no longer here from him again. i always say to beginners, the less you do,the less that can go wrong.i now people ho never do something wrong.

Ice