Question about Mastercool 67680 Evaporative Cooler Air Conditioner

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No power to water pump

I have power to the cooler. Fan comes on but water pump does not. I pulled the water pump and tested it. It works fine. The electical junction box inside the mastercool 2 unit where the water pump plugs into seems to be missing a plugable fuse. Above the plug is a space for a four pin "something". I think that might be what is preventing getting power to the pump. I can not find the paperwork for the unit so I am not sure what goes there.

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  • eric_orton May 12, 2009

    I did find one similar question about the water pump before I posted my question. However, I must have only seen part of the answer because it did not give the info you provided.

    Yes I have a voltmeter. What are the steps?

  • eric_orton May 12, 2009

    Also, it is a 110v a/c unit with a thermostat.

  • eric_orton May 12, 2009

    I will have to wait until this evening when I get home to test.



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Posted on May 12, 2009

  • Samuel Charles Spriggs May 12, 2009

    This is the second time I answered this -- system problems this morning.

    The four empty holes are most likely for the water pump relay.

    If this is a 110VAC unit with the thermostat on the unit, then this is probably the relay it needs:

    coil 110VAC

    single pole

    contacts 110/220 VAC 10 amp

    I doubt you can find that exact relay w/o a part number -- finding the correct plug would be the difficult part. But, there is a way to determine what type of relay you need and hook it up without actually plugging it into the holes.

    If you have a voltmeter, I can take you through this process., and advise.

  • Samuel Charles Spriggs May 12, 2009

    Well, the first part is pretty simple.

    With the unit/thermostat set to where the pump would be running, just set the multimeter on VAC and check the voltage across the "holes".

    Probes across

    1 & 2

    1 & 3

    1 & 4

    2 & 3

    2 & 4

    3 & 4

    What are readings?



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