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Woodtroll's avatar
Woodtroll
Explorer
Feb 04, 2014

How to tell if AC has a start-up delay? (EMS-HW30C Install)

Hello, folks,

I am preparing to install a Progressive Industries EMS-HW30C power supply protector in my trailer. In the manual, it states that if your air conditioner has a built-in restart delay you can use the short (15 or 20 second) factory setting on the protector, but if the AC does not have a built-in delay, you should remove a jumper "wire" inside to give the protector a 2-1/2 minute reset delay to protect the air conditioner from restarting too soon and damaging itself. According to Progressive Industry's documentation I am supposed to refer to the AC manual to figure this out. However, the AC is the one piece of equipment that did not have the owner's manual included in the document package when we bought the trailer new. This is a ducted, 13,500 Dometic unit installed on our trailer when it was built in early spring of 2003.

Is there any way to tell if this particular unit has its own, built-in start-up delay so I can use the short factory setting on the power supply protector?

Thanks,
Regan

15 Replies

  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Turn on the A/C.. if the blower starts, then 2 or 3 minutes later the COMPRESSOR starts, it has a delay

    That simple.

    Or you can turn the A/C on and then trip it's breaker, wait 2 minutes and turn it back on.. Again if the compressor comes on IMMED, no delay. if it waits 2 or 3 minutues, delay.
  • Thanks for the prompt replies! I had thought about starting the AC up and cutting the power, but its only 20 degrees F here right now, so I doubt I can trick the AC into firing up right now anyway! I might pull the jumper wire just to be on the safe side until I figure it out...
  • Cycle the circuit breaker when the air is operating, if it restarts immediately you do not have time delay protection, if it does not restart immediately you do have time delay protection.
    I have seen adjustable time delay relays that can be set up to ten minutes delay.
  • IF you have a wall tstat for the AC unit, you have the time delay. IF you have an AC unit with ceiling mounted mechanical controls you do NOT have the time delay. Doug
  • You may need to remove the shroud and take a peek. It should be a small plastic box perhaps 2"x3" with a dial on it to adjust the restart time. The technical term is a time delay relay. I had to install one on my home central air unit because of the frequent but momentary power outages here in FL. Having an AC restart immediately after an outage will cause short cycling which is the death of AC units.
    Another clue if you have a DTR is to momentarily cut power then turn it back on. If the AC doesn't restart immediately then you have a TDR.