froze up again!

[ronayne]

eh guys, thought you might have some ideas.
working on a general display cooler with a remote keeprite condensing unit. I am slowly converting over to refrigeration as a/c is starting to become boring so take it easy on me. Cooler is r22, box temp should be 38f, L.L.S.V., defrost clock set for 30 minutes every 4 hours.
pressure switch inside box set at 45 high & 5 diff. Pressure switch for compressor set to cycle off at 5p.s.i. Unit keeps cycling on L.L.S.V. box temp okay but every 2 months this sucker will freeze up. Oh yeah gauge 40low 19
high. clear sight glass.Could not find any leaks.

Thanks,guys.

[redwolf]

You mean a low pressure switch controls the LLSV and other one for pump down? Weird.
Differential is really low. What are they storing in the box?

Unit keeps cycling on L.L.S.V. box temp okay but every 2 months this sucker will freeze up. Oh yeah gauge 40low 19
high
Could you staighten this out some... Not sure if I completly understand what you posted.

[Edited by redwolf on 07-29-2004 at 12:25 AM]

[ronayne]

Sorry Redwolf, T-stat with a bulb controls L.L.S.V. and low pressure switch controls compressor.

[R12rules]

When you read the pressures, was the box down to temp and ready to shut off on the t-stat?

Whats the t-stat set for? Not the dial setting, but the actual cut in and cut out. Where is it operating?

What is your head pressure?

What temp is the suction line back at the compressor? Measure this six inches from the pot itself.

What is the condition of the evaporator coil?
Fins pretty much all straight?
No deterioration due to chemistry inside the box?
How is the drain on the evaporator coil's condensate pan? Is it freely draining?

Are the fan motors on the evaporator all running smooth? Are they all turning the same blades?
Are they all turning in the same direction?

Are there any noisey fan motors?

How are the door gaskets/ seals?

[jeffcolledge]

Wow R12, I think you covered all the bases! The only thing I could add to that is...are you sure the time clock is working? Set it to the exact time next time you're there, and come back again at lunch time or when you're on your way home for the evening, or maybe the next day and see if is maintaining proper time, if not, who's to say it ever goes into defrost? Good luck!



Oh yeah...leafs suck, GO WINGS GO!!!

[superfittertech]

also make sure the box fans stay on during defrost. You said it is a cooler so it should be just air defrost.

[R12rules]

Our host to this thread just added some info, in another thread. I will attempt to add some of it here.

He said the unit pumped down, which took about two minutes, then the compressor shut off. But it would not restart.

Sounds like bad start components. May want to investigate the caps and relay. Also how tite is the wiring at the compressor and starting components?

Might also want to tie on a thermometer probe to that t-stat probe so you get the cut out and cut in of the stat.

[mccool]

After interpolating all the discumbobulated gobbledygook about this fixture, I have deduced that the inadequate premature termination of the time continuom required to melt the accumalation of cryztallied condensate on the evaporator is directly related to the requirement of bi-monthly checkups.
Did'nt see that stuff about the startup components, sounds to me like inadequate defrost time/ or improper termination of defrost is the main problem, if only icing up after 2 months.
What is the model#, type of display fixture?
Need some more description of the fixture!
Try 2 defrosts @ 1 hour versus 4 @ 30 is a possible solution or better yet 3 @ 45 mins.

[frozensolid]

Maybe they have inventory every two months, and the bozos turn the fans off so they don't get cold.

[sparks]

Originally posted by frozensolid
Maybe they have inventory every two months, and the bozos turn the fans off so they don't get cold.

I love that one, I had a similar problem they wouldn't shut down the fans but they would prop the door open for 6-8hr during inventory. Of coarse I didn't ask until my second trip, drove me crazy first time out! Defrost was origanally timed termination only every 4 for 15min, changed the timer, put a termination stat on and increased the timer to 30min no more problems.

[frozenhead]

you got an air sensing t-stat and a pumpdown system i understand. if your t-stat are ever satisfied you could adjust your low pressure control to cut-in a little higher(60psi to 68psi but check your cut-in temp.) to allow your evap. to claer up of any frost.