404 system smell like sewer

[shaka]

Does that indicate a problem?

What causes that smell?

[markettech]

Not sure you can be more vague - What part of the system? Have you tested the oil for acid? Are you having a specific problem? A little background would be nice.:(

[shaka]

Last week I replace a compressor on an Italian made freezer (Cake Display)
( Bad valves, noisy)

The freon smells when I was recovering.

[markettech]

I would strongly suggest a filter change if you haven't already done so and possibly a suction filter for a week or two. My guess would be acidic oil. Did you do an acid test on the oil in old body?

[shaka]

No I did not check acid test.

I just treated like it was contaminated

suction, liquid drier

pulled to 380 micron and weigh in charge.

[shaka]

Also flush with nitro.

Inside of the copper was clean.

also broke vaccum twice with nitro.

[markettech]

If it were me, I would go back within a week (2 tops) and check oil again (or in your case the first time), change liquid filter/drier and if there is still acid, change the suction filter. I would keep doing this until acid test came back negative. If no acid, I'd cut suction filter out and repipe line.

[shaka]

I would if I felt that the compressors failure is due to a burn out or
high acid.

I believe the cause of failure was due to the design of this particular
equipment. (liquid flood back)

Its a small unit and defrost method is hot gas.
defrost time was too long.
with no accumalator.

[engineerdave]

Dude -
Markettech is on target. Nasty smell = acid. Best to clean him up. I'd probably replace the oil as well.

[markettech]

I would if I felt that the compressors failure is due to a burn out or
high acid.

I believe the cause of failure was due to the design of this particular
equipment. (liquid flood back)

Its a small unit and defrost method is hot gas.
defrost time was too long.
with no accumalator.

Just because the compressor failed mechanically doesn't mean there is no acid in the oil. If there is acid, you will be back changing another compressor before long.

You asked what the smell could be from and I told you what I thought based on the VERY limited information given. There are times when more than one problem present themselves on the same piece of equipment.;)

You're there, I'm not - do what you wish:)

[Airmechanical]

check oil acidity level first, if it is high, replace suction
dryer, at the same time throw in the prescribed amount of acid away.
otherwise dont worry about the smell.

i have been told when all of us start using recycled r-22
they wont recycle the (smell out of it)

you did'nt use reclaimed/recycled/ or recovered freon did you?
you know that illegal unless you got it off that jobsite!



.

[smilies]

Last week I replace a compressor on an Italian made freezer (Cake Display)
( Bad valves, noisy)

The freon smells when I was recovering.

Sevel case? If so, 2 minutes on the HG defrost x 6. Seemed short to me at first, but it works.

[shaka]

Thank you for you reply

sadly I wont be able to go back to recheck.

They wont pay for it.

But I did all I can while I was there
and yes I did add some of the snake oil (acid away)

That was the first time I came across that smell.

What causes that smell? I know you guys said it was acid
but I worked on all kind of contaminated system
but that was the first one that smells that bad.

[RobY]

That was the first time I came across that smell.

What causes that smell? I know you guys said it was acid
but I worked on all kind of contaminated system
but that was the first one that smells that bad.


The R-404A system should have POE lubricant in it. The acids formed when POE breaks down are organic acids, and they smell like rancid fat or a decomposing animal. Not a pleasant smell.

The use of Acid-away to band-aid the system removes the acidity, but is a poor choice for system longevity. Once the POE starts breaking down, it becomes less stable to further breakdown. The stability of the POE depends on having every available alcohol group attached to an acid, and if some acids are knocked off due to breakdown, the exposed alcohols are points of chemical weakness. The partially broken down POE will fall apart much easier than new POE.

If you smell rancid oil, then change out the POE and the filter driers until all the acidity is removed if you want the system to be stable.

Rob Yost
National Refrigerants

[the mojo]

Roby,What are some of the chemical additives used in POE to increase it's lubricity? And which of those chemicals start to break down first or second when exposed to slighty higher than normal head pressures?

[RobY]

Phosphate esters are the most commonly used lubricity additive, very similar to what had been used with POE lubricants in jet engine lubes since the late 1950s. The phosphate esters are almost as thermally stable as the POE, and survive up to 350 degrees F. The phosphates can be designed to be more reactive and give better results in wear testing, but are then less thermally stable at higher temperatures.

POE refrigeration lubricants do not usually use lubricity additives, and there are very few OEM required uses of them. The McQuay screw is one of the ones that uses phosphates fro lubricity. Tecumseh uses phosphates to chemically inhibit iron surfaces to reduce reactions with POEs at higher temperatures.

Rob Yost
National Refrigerants

[the mojo]

Thanks Rob, This was just an idea that came to mind. Reasons for Thermal breakdown excluding a moisture condition I'm sure has "haunted" many a technician. Also extended abnormal head pressure in the area of no more than 10-15% normal ambients has always been a cause of concern. It just feels that mineral & AB oils were not such an issue when it comes to coked TXVs and solid contaminate problems that occur with POE today.