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  1. #1
    Join Date
    May 2009
    Location
    The Pas, Manitoba Canada
    Posts
    212

    Dixell thermostat display accuracy

    I am working on a small display cooler that is freezing the salads. I am not familiar with the case manufacturer but the problem is that the Dixell mod#XR40C electronic thermostat will run fine with case temperature display working fine then the display temp jumps from 40 deg F to 53 deg F and the the unit won't shut off. Turn the unit off and on and the display shows accurate case temperature again. Has anyone come across these thermostats and similar trouble?

  2. #2
    Join Date
    Jun 2009
    Location
    DFW, TX
    Posts
    675
    Never seen one have the temperature jump like that. I would suspect either a loose connection in the cabinet (air) probe or possibly a faulty probe. Typically there is either one or two probes, and the usually share a common terminal on the terminal block. The wires could be corroded, or frayed and causing intermittent issues, or of course the probe could just be faulty.

    What I HAVE seen on many Dixell controllers, is the manufacturer will wire the control to directly energize the compressor. Despite the fact that the control is rated for 16A or something like that, the little micro-relays inside the control OFTEN will "stick" and cause the unit to just keep on running and freeze the food. "Tap" on the control and it will start working fine. But if this was the case, you would see a temperature on the display that is lower than your setpoint; the control doesn't think it is energizing the compressor, but it is. The solution is an external relay or contactor - to take the load off of the controller. But again, this doesn't sound like what you are experiencing.

    It sounds like the probe is intermittent, causing control to stay energized because it thinks the box is too hot.

    If the probe wiring looks solid, you may try to ohm out the probes while wiggling the probe and wires to check for an intermittent issue.

    Of course there's always the weird stuff that you may run into... Some of the Dixell controllers have an option to display a certain temperature during defrost; and some have an option for a 3rd probe that is for display temperature only, but does nothing to control the unit. I can picture something weird, like unit goes into defrost, but relay sticks, causing unit to keep running and freeze food... or unit was set up for hot gas defrost but didn't have hot gas, which would cause compressor to stay energized continuously during defrost But I just have a vivid imagination. I always have to remind myself "THE SIMPLEST SOLUTION IS USUALLY THE CORRECT ONE!"

  3. #3
    Join Date
    May 2009
    Location
    The Pas, Manitoba Canada
    Posts
    212
    Probes are ok there was 1 loose probe connection at the controller. Tightened things up and good so far. The cooler was just freighted 600 Kms. and probably got shook up a bit.

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