Dometic Fridge Blowing Fuse

[jimnina]

So we started having a problem with our dometic fridge when we switch between LP, Shore, or Genny power. This started after we had a shorted out surge protector that pushed 160v through out the 120v circuits. The 5A fuse in the fridge did its job and popped. I found new 5A fuses and replaced the blown one on the circuit board. What I didn't do is determine what type of 5A fuse should I have searched for. As long as I switch the fridge off before switching power the fuse doesn't blow and the fridge cools like it should. I searched on line and couldn't find anything that might tell me if I should be using a slo blo fuse since I may just have a normal fuse. Any help would be appreciated.  

[Kirk W]

So?  I would go to Bryant RV website and download a copy of the appropriate Dometic service manual. In it, you should be able to find the appropriate fuse to use. There exist a very wide range of fuses in terms of speed so it would be risky to use a slow blow fuse where it isn't required. It also sounds like your heater is drawing more than the normal current as it should not be that sensitive. Normal operating currents on most refrigerators run closer to 3a than to 5a except when there is the brief starting surge. Using the wrong fuse could come back to haunt you at some time in the future.

[jimnina]

Thanks Kirk,

I'll have to wait until the weekend to get the model number from the fridge.

[Dale P]

Standard 3AG fuse is used.

You cabn visually see the difference between the fuses

[oldjohnt]

In the fridges I had occasion to work with (several over many years) the fuses used WERE NOT slow blow (but no idea if they were original or not). Of course, that's NOT to say your particular model doesn't use one. FYI slow blow are typically used where there's a high initial in rush current (like say a motor for instance and some other loads) higher then the normal operating current. 

 As always, consult the owners manual and do as it suggests NOT anyone here.

 Iffffffffffffff you have the right fuse and it blows easy and often, I suspect another problem which is hard to diagnose sitting here (or even there for that matter).  No idea how you got 160 volts to 120 volt circuits as you posted??? but if that actually happened its no tellin what kind of a fault or short or low resistance (therefore higher then normal current) potential fuse blowing path may have been accidentally created. 

Hope this helps, best wishes safe travels and God Bless

 

John T

[Wrknrvr]

 In real world expierence

With the power to the fridge disconnected, disconnect wires to the heater, plug the power in  and repeat what sequence was making it blow the fuse. See if it does or not blow the fuse. 

That will determine where the problem is. Board or heating element.

 But I would bet there is a problem with the element shorting to the side of the heating element .  Remove the heating element and look for a swollen area on the element itself.

 You could check the ohms on the unit. Also check wires to ground  

 But I have seen them be intermittent and really make you think.

It can test good but still have its fits and occasionally short out and blow the fuse.

 If you try and wiggle the element when it is cool and it is stuck or hard to remove that is an indication that it has a problem 

 safe travels,.  Vern

[STEVEN FRANCIS]

HOW DO YOU REMOVE THE BLACK COVER FROM THE FUSE PANEL. I REMOVED THE TOP CENTER SCREW AND I DONT SEE ANY OTHER SCREWS. DOES THE LOWER COVER SLIDE OR PULL OFF?

[Kirk W]

Welcome to the Escapee forums!  It would be helpful to know more about what you have? It has been more than 4 years since the last post prior to yours but I am assuming that you have a Dometic refrigerator that you are working with? There are some differences between models. To remove the cover on many of them you loosen the screw on the top and then use a screwdriver in the slots on the side to pop the tabs loose. Be careful not to break any wires or the cover. Let us know more about what you need and if this is of any help,

You may want to start a new thread if this doesn't help since some members don't read the older threads. 

[STEVEN FRANCIS]

HAVE A NEW 2454  DOMATIC 3 WAY REFRIGERATOR THAT WAS INSTALLED BY AN AUTHORIZED AIRSTREAM DEALER. WORKED FINE UNTIL SAT WHEN I UNPLUGED TRAILER FROM 30 AMP POWER WITH REFRIGERATOR ON AC POWER. WHEN PLUGGED BACK INTO AC POWER , REFRIGERATOR  HAD CHECK LIGHT ON AND NOT COOLING. I SHUT REFRIGERATOR OFF AND THEN BACK ON. WILL RUN ON DC AND GAS BUT WILL NOT SWITCH TO AC, EVEN USING AUTO MODE. CHECKED ALL CIRCUIT BREAKERS AND SWITCHES. CHECKED PLUG IN RECEPTICLE  , ALL OK. PULLED CONTROL BOARD COVER AND CHECKED 3AMP AND 5 AMP FUSE .STILL NO AC OPERATION. BOARD AND HEATERS BRAND NEW. I SAW  SOMEWHERE THAT THERE IS A FUSEALE LINK WIRE TO THE HEATER. PLEASE ADVISE .

 

 

 

 

[Kirk W]

IF YOU DON'T MIND IT WOULD MAKE YOUR POSTS MUCH EASIER TO READ IF YOU DO NOT USE ALL CAPITAL LETTERS.

As for a fusible link in the wires to the 120V heater, I have never seen one in any of the Dometic refrigerators that I have worked on and the schematic from Dometic does not show one. The schematic does show a 30A fuse but it is in the 12V-dc line to supply the 12V heater and not on the 120V side. Have you measured the 120V supply to the refrigerator? Most of them connect to 120V with a plug into a standard outlet so you could use a lamp or electrical device to verify power. As you look on the schematic the L is for line voltage and N is for neutral. The S is the terminal block where 12V connects. There is a drawing on page 10 of the Dometic Service Manual that will show you what you are looking for. 

If this is a new refrigerator, I would be very careful to not do anything that might be considered a violation of the manufacturer's warranty by the dealer, as you may need to take it back to them. 

[oldjohnt]

If its constantly blowing the 5 amp fuse (regardless if regular or slow blow) that protects and leads to the fridges 120 VAC heating element, I suspect its (or wiring from board to element) bad and/or shorted to the sheet metal where and into which its located. If you disconnect the elements wires an ohm meter should read an open circuit (approaching infinity ohms) between either side and the conductive case/frame case of the fridge..

 If there's no shorts (wiring or heating element) and the fuse is fine, check the element for continuity terminal to terminal.

 The eyebrow panel (if so equipped) and/or the circuit control board and its relay is what controls and sends 120 VAC to the element (if on AC), if either is bad you wont get the 120 AC to the heating element and NO cooling

 As noted above the fridges rear plug needs connected to a good working live 120 VAC receptacle, that's any easy check.

 John T

Edited September 20, 2021 by oldjohnt