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Walk in Cooler

Hi all,

Got some info for you to digest.

Bohn cond. m#BHT015H2cf S#T98J01118. Heatcraft Evap M#ADT104AJ S# D98F04155. Sporlan TXV BFVE-A-C. 5/8 suction, 3/8 liquid. Cond above evap on top of cooler. Less than 10ft of line set. R-22.

Called because Evap froze up. Checked system today and found middle of evap frosted and frost from dist to coil. No frost on top or bottom of coil looking at the back of unit, but frosted clear thru the middle. Attatched gauges, 20 lbs lo, 190 hi. Taken at service ports on outlet of cond. coil. Did not take sh or sc. Site glass clear, headmaster did not seem to be bypassing. Left comp. off and evap fans running. Box temp at 40 degrees F. ambient at 70 to 75. The cooler is inside a distribution center.

came back 21/2 hours later. Coil clear. Started up unit. Box is empty and 60 degrees. Let unit run and took sh and sc. Maintained 20 sh at txv and service valves. Site glass still clear. Box at 40 degrees, 38lbs lo, 190 lbs hi, 34 degrees at txv bulb, 38 at service valve. 82 at liquid line service valve. 75 degree ambient at cond. site glass still clear.

Talk to customer contact, had mentioned that they had charged it lately. He told me that they had put 2 pounds in it last week. After that it was freezing up on the bottom of the evap coil. They let it defrost and now it frosts up in the middle. Told him I would come back tomorrow and see if the stat is shutting off. I know that today I saw frost, not ice. That tells me the unit did not shut off and thaw. I do not know what the customer saw, frost or ice?

Unit has no defrost clock. Stat set at 38-39 on and about 5degree diff. No pump down, stat controlls contactor only.

Suction press. seems low for 40 degrees in box. SH a little hi but not a long line-set and not at cut out temp and no load in the box. Liquid line press also seems lo and riding on the headmasters bypass point. Need to get the setting tomorrow! Should be 180, but you never know!! Asked the customer if they found the leak? No, guess there wasn't one. I said if they put in 2 pounds there is probably a leak, but what if it was not charged properly? System is about 8 years old according to the Serial numbers.

Do I have a bad txv, stat, comp. or what. Just looking for some opinions. Will make up my mind tomorrow, I hope! And will try to get any info anyone needs!

Don in Moberly MO

Comments

  • bob_50
    bob_50 Member Posts: 306
    I'll bet

    that sight glass is clear because it's empty.


  • The more I think about it the more I wondered if it is low on charge, but with over 10 degrees of subcooling, I'm not really seeing it that way.

    I went back today, but only to visually check it. Boss has scheduled me for to much work. I was running 35 to 39 degrees. It did shut off. Before it did I noticed that the inlet of the coil was iced, telling me it was shutting off. But still acting like it is low on charge.

    Talk more with the customer and told me that every once in a while they have to defrost the coil completely. I am thinking of putting in a defrost cycle for 30 min. once a day. Also thinking of recovering the charge and checking the screen in the txv. I have a chart for that unit with total charge.

    Will see if I have time to mess with it and if the customer wants to spend the money, since it is "working" now.

    Don in MO
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