changeover to 401b
Results 1 to 10 of 10
  1. #1
    Join Date
    Jun 2004
    Posts
    55

    Confused change over too 401b or mp66 defrost

    hi,sorry about info last niteon freezer i added somemore 401b and change gauge locations sc is now 11 to 13 degrees
    freezer is around 12below having some problems with defrostwhen in defrost the evap stops heater comes on bottom of drain pan but comp keeps on running their is a solinod valve on liquid line but no changes on gauge psi
    can someone tell me what too expect with this type of defrost system? thanks ken

  2. #2
    Join Date
    Jan 2004
    Posts
    526
    is it for a pump down cycle

    [Edited by bmf on 07-20-2004 at 05:32 PM]

  3. #3
    Join Date
    Jun 2004
    Posts
    55
    i am not sure if this is a pump down cycle their is too psi controls at comp one for low psi and one for hi psi and one inside of freezer for temp control this one inside is not a tstat

  4. #4
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,247
    Originally posted by kc8939
    i am not sure if this is a pump down cycle their is too psi controls at comp one for low psi and one for hi psi and one inside of freezer for temp control this one inside is not a tstat
    I can't imagine that the control inside the box is a pressure control. There are commercial t'stats that "look' like pressure controls if you're not looking closely.

    The compressor should not be running during the defrost cycle (except maybe for a short time initially to pump down the system). The liquid line solenoid valve should be controlled by the defrost clock and the thermostat in the box in series through the #4 terminal on the clock.

    If your in defrost and it's not pumping down then I would guess that the LLS is not closing. If the LLS coil remains energized during defrost, check your wiring.

  5. #5
    Join Date
    Jun 2004
    Location
    St Paul, minnesota
    Posts
    1,106
    If the solenoid valve is deenergized &compressor is running in a vacuum you might have a bad low pressure switch

  6. #6
    Join Date
    Jun 2004
    Posts
    55

    Smile defrost changeover too 401b

    hi,all thanks for help the unit is running great, the dfrost is as foolows evap fan stops, lls closes comp runs long enough to pumpdown too lp setting then if psi goes up comp starts too pump down again untill psi drops is this right it seems like it is. but it seems like the hearters dont remove all of the ice on one end of evap the side that has tex and lls onit.thanks ken

  7. #7
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,247
    First, a matter of housekeeping.......

    Ken, don't start a new thread on this because it's a continuing discussion of the original problem you posted. I see you did add this post to the old one and that would have been fine.......and a lot less confusing for the rest of us.

    Does this evaporator have a defrost termination thermostat? It's usually a Klixon-type of t'stat clipped to a return bend or attached flat on the tube sheet of the coil to sense coil temperature. They would typically be wired to the "X" terminal on a Paragon 8145-20 (If that's what you have for a clock).

    It can also be a three-wire Klixon which includes the post-defrost fan delay. Some coils even have adjustable termination thermostats, then again some have none at all.

    What's in your Coil?

  8. #8
    Join Date
    Jun 2004
    Posts
    55

    Question change over too 401b or mp66 defrost

    hi, icemeister,
    sorry about post not sure if it would be read or not . yes their is a klixon on the side of the tube sheet could thys be bad this is on the side that still has an ice buildup
    it is a two wire.the top heater seems too be hotter than the other heaters,also not sure what model of timer this is.

  9. #9
    Join Date
    Jun 2004
    Location
    St Paul, minnesota
    Posts
    1,106
    check defrost timer. if it's a paragon 8145-20 & has an "X"
    terminal with a wire hooked up & the termination switch that you found has one of its wires hooked to it , then you need to increase the time on the defrost timer I usually set to 30-45 minutes depending on the traffic in & out of the box

  10. #10
    Join Date
    Jun 2001
    Location
    San Diego, CA
    Posts
    1,149
    Yup, increase time but . . . if the X term trips before the timer does with ice still in the box you're fighting a design issue. Try moving the Klixon further up the suction line toward the compressor. Heck - place it on the suction line just as it exits the coil, that'll defrost it for sure.

    g

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event