What am I missing?
A little background first, I am owner/operator of a commercial refrigeration service company, got called on this fish freezer for complaint of temperature not cold enough. Customer found one lower fan motor dead and both ambient air curtain motors were dead. I travelled the two hours to site replaced and checked. Ambairfilters and Honeycomb cleaned at same time. Good even airflow through all honeycomb tested with smokestick.
The fixture is a Hussmann G6F-8U multideck freezer holding frozen fish and shrimp. The problem is that the fixture recently started bottoming out at -10C/14F. It normally bottoms out at -17C/1.4F setpoint is -20 to ensure it never cuts out before then.
This fixture is in a store on the same level 100feet or so away from the LALA-032E-TAC-800 low temp compressor that serves it. Here's some info for you:
Solenoid Valve controlled by A419 temp controller
225lbs discharge(95F condensing)
Suction at 20lbs
Superheat at 6deg but have tested 4 through 8.
TXV is an HFE 1-1/2 RZ strainer is clear on this and the suction service valve on the compressor.
Amp draw of 9.5amps @ 14F 10.8amps @ 28F (12.6 Rated Load Amps)
Standing pumpdown test indicates pressure rise most likely due to leaking suction service valve as I pulled the head and valve plate to confirm no broken reeds or broken con rod on one piston, amp draw would be lower anyways on one piston but it's been checked.
Checked defrost heaters to ensure they were not being energized during reefer cycle. No amps, or voltage to them.
I just downloaded the original fixture manual from Hussmanns site so will be going throught that. The fans have always been on in defrost mode even when the temperature was cold enough. I will check but it looks like this is design as one of the heaters is in the return air duct at front of case and the next 6 inches before bottom evap. First time I've seen one that has fans on in defrost if that is right.
Any ideas on what I'm missing? This occurred overnight from good to not good. Not slowly over time. What are your thoughts?
I appreciate any help, no such thing as a stupid question either. Let 'er fly!
The Hussmann G6F, and all open cases for that matter, do not shut down the fans during defrost...so that's quite normal.
I'd say you're on the right track about the valves because according to the performance data for that compressor, at 20 psig suction and 225 psig discharge with R404A it should be drawing 11.5 A. If I'm reading your results correctly, you got only 9.5 A at that condition...so it may be time for a new valve plate.
I am taking a valve plate kit with me but I saw no damage to the valves when I pulled it out. The pressure rose on the pumpdown test but as there was no visible damage when I then pulled the head, I assumed the isolation valves weren't holding. There is visible wear circles on the reeds but no cracks or bending so I'm not too sure if the old one is bad. But for that matter at two hours away, it's cheaper to gamble with the price of the new valve plate...
Thanks for your response, you saved my bacon as I was driving out of town to the site when I read your reply and that reminded me that I had left the valve plate kit on my office desk. I hope I can help you out someday in return!
News of your success will my reward.
Originally Posted by koolkahuna
Icemeister, if my success is all you need then consider yourself rewarded! The problem was with the valve plate, nothing visible but new plate in and unit working properly.
Originally Posted by icemeister
This was a relatively new compressor, 1.5 years old or newer, wish I knew what caused the first valve plate to fail. I'm wondering if the regular powerspikes, bumps and failures could contribute to system eating liquid due to bypassing proper pumpdown procedure. Very poor power grid out that way. Regular repairs to burnt coils on contactors, burnt motors, etc.
Anyways, thanks again, sorry it took so long to get back to you. It's been a busy summer.
I carry 2 or 3 extra valve plates in my van always. it seems like its the calls that takes 2 or 3 hours travel that give you fits. it makes for a good day when you solve a problem like that. I am glad you solved it. have a rest of a good day.
a stupid question is a question you wont to ask, but don't