What killed the compressor?

[parks71]

One of my techs did a warranty call on a 3 door True freezer and the compressor was out. He changed it out, 2 days later our company is bought out and 3 techs quit including the one that did the job.

A week later the customer calls and says the unit is not working. I go out there and check it out and find bad starting components, replace them, the compressor starts right up with no problems.

I put my gauges on it just to check out what he did and while I dont remember the preasures, they looked good, the box came right down to temp and I was out of there.


2 weeks later (today) they call and say its making a loud noise. I go and look at it and it sounds like the valves are shot. I have like 7 calls and dont have a lot of time to put on it because I thought maybe a fan blade was touching or something making noise. I check the preasures and the suction is 0 PSI and the head preasure is like 350 and the compressor is BURNING hot around 300. I let out a small amout of refrigerant just to smell it and its smells burnt. The box is however at temp.

At that point I close off the liquid line to see if the system will pump into a vacumm and the head preasure sky rockets rapidly, in 2 seconds if that well over 400.

What do you think could have happened to cause this so rapid? I asked the guy that helped him install it and he said they vacummed the unit and put the right refrigerant in ect. Nothing fishy according to him with the install.

Just trying to see what you guys think and well see whos right when I go and put in the new one friday and check out the system most closley.

[Freezeking2000]

plugged filter drier! or a restricted cap tube.

[rickl]

I go with the difficult one, Cap Tube. I not lucky enough to find just a restricted drier.

[parks71]

Lol Rick, in almost 8 years of doing strickly refrigeration, I have yet to be "lucky" enough to just find a restricted dryer either hehe.

[parks71]

The only thing that leads me to believe its not a cap tube is usually you get a low head and it usually takes a long time to reach temp if ever and the customer told me he hears it kick on and off through out the day and its used a lot because its in a oriental market where people shop. Semi hermatic compressor if it matters to any of you.

It also has the large colored light at the top of the box that goes off if its not at temp and that hasnt happened. My guess right now is lack of oil but well see.

[icemeister]

It appears to me that the other guy changed out the compressor (without changing the start components)and after starting it up discovered that the factory charge (34 oz R404A, I think) didn't cut it due to partially plugged cap tubes (this case has TWO caps).

He then overcharged the crap out of it until he got some kind of suction pressure, not too too high of a head and called it a day.

He probably didn't give the condenser a good cleaning either.

He left the new compressor to deal with the same conditions that killed the first one.

That's what I think.

[Edited by icemeister on 03-01-2006 at 07:33 PM]

[jeep6275]

10-4

[parks71]

Ice, I dont know how many cap tubes it has because I havnt went that far yet but I do know the coil was spotless. It does have a crank case valve on it though and maybe he did overcharge it but the head was dead on when I did check it so why would it have burned up? You do have one thing right though he didnt weigh it in.

[Edited by parks71 on 03-01-2006 at 07:42 PM]

[cyro]

Dido on icemeister,

clogged and over charged.

[brybo nc]

do you mean that you closed off the discharge line on the compressor? that would definately cause that head pressure to shoot up.

[k-fridge]

Cap tubes. May also have a floating restriction. While you have it down blow it out from the discharge line to the dryer.

[thegoodhumorman]

[QUOTE]Originally posted by icemeister
It appears to me that the other guy changed out the compressor (without changing the start components)and after starting it up discovered that the factory charge (34 oz R404A, I think) didn't cut it due to partially plugged cap tubes (this case has TWO caps).

He then overcharged the crap out of it until he got some kind of suction pressure, not too too high of a head and called it a day.

He probably didn't give the condenser a good cleaning either.

He left the new compressor to deal with the same conditions that killed the first one.

That's what I think.

[Edited by icemeister on 03-01-2006 at 07:33 PM]


ditto on this statement -
theres a reason they call them critical charge.....

[luvcldair]

I would say moisture or non condensables

[ispip]

well seeing that the refrigerant smelled burnt, you have to change the refrigerant anyway. i would change the drier and try to blow out the or change the cap tube. the unit sounds over charged to me. so wiegh in the new refrigerant.

[coldking]

I worked on one of these had the same problem. Changed bad compressor with one that came from True, whan received compressor model # did not match the original. I called True they assured me that it was the proper compressor, it ran well for two weeks. Then True says sorry we sent you the wrong compressor. Insalled correct compressor, found cap tube restricted, replaced cap tube, then cpr failed replaced cpr unit has run fine except for the usual True cold control failure. Customer was very happy it was still under warranty

[stormrider]

The True 3 door freezers are equiped with a CPR. Did check its setting?

[jayhawker]

POE oil can cause a intermitent restriction that moves around if the system has to much moisture for the filter drier to handle.-0ppppppppppppppppppppppppp < the cat just stepped on the key board

[hillbilly tech]

One answer,True.404 and stopped up cond.do not jive.Your asking for trouble the first time you have a round with these 2 or 3 door freezers.Been there,wont be back.