Forum Discussion

leatherhead612's avatar
leatherhead612
Explorer
Aug 17, 2016

AC wasnt working

Ok, so i just replaced my TT battery. I inadvertently hooked up the cables backwards (dumb, i know). I noticed the screwup about 15 mins later and fixed the mix up. We went on a trip, and everything was working fine. Then the AC quit working and the fridge would not work. I checked all breakers with none tripped. I looked at my fuses and the 2 40 amp fuses were broken. I went to wally world, and replaced them with 30 amp (as they did not have 40 amp fuses available. Will this work until I can buy 40 amp replacements? After replacing them the ac and fridge work now. Would these polarity protection fuses cause the ac to not work? And if so why did the AC work even tho i initially hooked up the battery cables backwards? I dont quite understand what these 2 fuses have to do with ither than the polarity protection

9 Replies

  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Aug 20, 2016
    Don't look too hard or you may just find "The Answer". When unarmed and grazed by a bullet, I do not go searching for the shooter. Reverse polarity caused the problem, fuses rectified it and time has proven the fix.
  • leatherhead612's avatar
    leatherhead612
    Explorer
    Aug 20, 2016
    Well replaced the fuses, and about 400 miles later, everything is working great. Must have blown the 15amp fuse on the jensen audio too cause had to replace that as well. Thanks everone for the help.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Aug 17, 2016
    Ok, here is what happend
    When you hooked the battery backwards, that is you REVERSED the POLARITY. the REVERSE POLARITY fuses in your converter blew (the two 40 amp fuses).

    Dang.. To be honest that is not all that common, Normally a 40 dollar pass transistor blows in order to protect that 40 cent fuse (old Electronics Technician joke, and yes, I resemble that remark).

    Well everything worked however..... Till the batteries ran down.

    Now to your quesiton: will the two 30's work till you find two 40's.

    Odds are.. yes. If they are working now they shoudl continue to work. In fact the "Acid Test" of those 30 amp fuses was "Did they Hold when you plugged back in after installing them) If they were going to blow.. The odds are that is when they would do it For the batteries are very very hungry.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Aug 17, 2016
    wnjj wrote:
    Old-Biscuit wrote:
    Converter should have continued to supply DC Dist System even with the reverse polarity fuses blown (they isolate battery from converter to protect converter)


    Not necessarily. For example, the Progressive Dynamics converter instructions here show only 2 wires from the converter to the battery and loads. The fuses protect the converter by isolating it from everything, not just the battery.

    So what may have happened is the blown fuses meant no 12V charging and the A/C & fridge ran until the battery drained enough to cause them to fail. With the replaced fuses, the converter immediately supplied 12V power for charging and use by the A/C and fridge.


    True for that model of converter.
    Would explain how AC/Fridge had low DC voltage.


    Mine feeds DC Dist Panel with separate cable connection......reverse polarity fuses isolate battery.
    DC system supplied IF on AC power just no battery charging.
  • wnjj's avatar
    wnjj
    Explorer II
    Aug 17, 2016
    Old-Biscuit wrote:
    Converter should have continued to supply DC Dist System even with the reverse polarity fuses blown (they isolate battery from converter to protect converter)


    Not necessarily. For example, the Progressive Dynamics converter instructions here show only 2 wires from the converter to the battery and loads. The fuses protect the converter by isolating it from everything, not just the battery.

    So what may have happened is the blown fuses meant no 12V charging and the A/C & fridge ran until the battery drained enough to cause them to fail. With the replaced fuses, the converter immediately supplied 12V power for charging and use by the A/C and fridge.
  • Diesel_Camper's avatar
    Diesel_Camper
    Explorer
    Aug 17, 2016
    Well I'm not sure where the fuses are in relation to your converter, but if every thing is working now I'd say the fuses were between the charger and battery so if they were blown, no charging. I'm not sure why your converter wasn't powering the AC thermostat and fridge, but I'd need to see your system to figure that one out.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Aug 17, 2016
    AC worked so you must have been connected to shore power.........

    Converter should have continued to supply DC Dist System even with the reverse polarity fuses blown (they isolate battery from converter to protect converter)

    Need to check converter DC output....it may be failing
    With 120V AC input to converter the DC output should be 13.2 minimum
  • leatherhead612's avatar
    leatherhead612
    Explorer
    Aug 17, 2016
    Thanks for the quick reply. That makes perfect sense. This forum is great. Thanks! I did notice the battery level on the monitor was low, guess the battery wasnt getting charged with the blown fuses. Would that matter even though I was connected to shore power?
  • Diesel_Camper's avatar
    Diesel_Camper
    Explorer
    Aug 17, 2016
    You should be fine with the 30 amp fuses. Keep some spares around though and get the 40's when you can. The fridge and AC thermostat both use 12v power, that's why neither worked with the fuse blown.

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