Norcold 1200 series fridge blowing 5 amp AC fuse

[mxdad777]

I have a 2005 Norcold 1200 series fridge with a 621271 circuit board. When I turn it to AC power the 5 amp glass fuse blows within about 5 to 10 seconds. I checked both heater elements and they ohm out at 59.7 and 59.8 (both within specs). Just for fun, I tried unplugging the ice maker but the fuse still blew. The fridge seems to run fine on LP. Is it time for a new board or is there something else I might be missing? Thanks in advance for any help.

[dougrainer]

You CANNOT repair the cooling unit. I would go for the "Amish" replacement. Look up Amish 1200 cooling units on Google. Doug

[MrWizard]

bad news.. I think you will need a new cooling unit

my luck with 'repaired' cooling units was a disaster

other people will have had different results

[mxdad777]

Good news and I think some really bad news. I found a blown 5 amp 12v fuse and that fixed my problem and the fridge turned on and works great. The bad news is while buttoning up the project I thought I could hear a very faint hissing sound coming from just above the burner. I sprayed some windex and there are very, very tiny bubbles forming between the two tubes that the burners slide into. My guess is when removing the old burners (I had to twist them back and forth and pull pretty hard) there is now a pin hole in the cooling unit. Upon further inspection, I can see small traces of yellow around the gas burner and on the inside of the insulation that was wrapped around the burner elements. I turned off and unplugged the fridge and called it a night. Is this something that can be repaired or am I looking at a complete new cooling unit? Once again, thanks for all the help.

[dougrainer]

mxdad777 wrote:
Now I'm puzzled. I replaced both elements and the Thermistor, put a new 5 amp fuse in and I have nothing! I'm getting 120 volts through the fuse but when I try to turn the fridge on I get nothing. I've double and triple checked that I've connected all wires correctly and everything appears fine. I might add that during this whole process I removed the circuit board from the coach to inspect all the solder connections on the back of the board. Everything looks like new on the board except for a slight heat mark behind the large blue resistor which I see is common on these boards. Any ideas what might be wrong or what I might be over looking?

Remember, the Refer operates from 12 volt control. Make sure the 12 volt Neg and POS feeds have voltage. Make sure you connected them on the correct spades. Make sure the recall box is connected correctly. Make sure the 12 VOLT fuse on the board is not blown. Doug

[mxdad777]

Now I'm puzzled. I replaced both elements and the Thermistor, put a new 5 amp fuse in and I have nothing! I'm getting 120 volts through the fuse but when I try to turn the fridge on I get nothing. I've double and triple checked that I've connected all wires correctly and everything appears fine. I might add that during this whole process I removed the circuit board from the coach to inspect all the solder connections on the back of the board. Everything looks like new on the board except for a slight heat mark behind the large blue resistor which I see is common on these boards. Any ideas what might be wrong or what I might be over looking?

[dougrainer]

mxdad777 wrote:
Doug, I don't think the Thermistor is causing the fuse to blow, but for the last few months the fridge wasn't getting as cold as it used to. Even on the setting of 9, milk and soft drinks would be cool but not cold. During my research regarding the fuse I read about the roll a Thermistor plays. When I checked mine it showed an open circuit. I don't understand how it was working at all. So to answer your question, no I don't think the Thermistor has anything to do with my original problem. On the other hand, I also can't figure out why my elements ohm out in spec and also show no sign of a dead short. But I'm replacing them anyway because you do sound like this isn't your first rodeo with the 1200. Thanks for your help.

1. A GOOD Thermister can OHM out to spec, so replacing it is a good idea
2. Marginal cooling usually indicates lack of the rear fans operating. Have you checked to make sure the rear fans come ON? Doug

[mxdad777]

Doug, I don't think the Thermistor is causing the fuse to blow, but for the last few months the fridge wasn't getting as cold as it used to. Even on the setting of 9, milk and soft drinks would be cool but not cold. During my research regarding the fuse I read about the roll a Thermistor plays. When I checked mine it showed an open circuit. I don't understand how it was working at all. So to answer your question, no I don't think the Thermistor has anything to do with my original problem. On the other hand, I also can't figure out why my elements ohm out in spec and also show no sign of a dead short. But I'm replacing them anyway because you do sound like this isn't your first rodeo with the 1200. Thanks for your help.

[dougrainer]

mxdad777 wrote:
I ordered two new elements today and also a new Thermistor. I'll replace them this weekend and see what happens. My coach is 12 years old and is plugged into power when we are home with the fridge running. If this fixes my problem, I'll feel pretty fortunate that this has been my only problem.

I am curious. WHAT reading led you to a Thermister causing your problem? It CANNOT. ALL it does is send a signal to the control board to turn the refer On and Off to cool. If this helps you in your decision--I am a Master Certified RV Technician. I have 37 years experience and still working. I doubt anybody on this forum or in the RV business has as much experience and expertise on the 1200 Norcold as I have. Doug

[mxdad777]

I ordered two new elements today and also a new Thermistor. I'll replace them this weekend and see what happens. My coach is 12 years old and is plugged into power when we are home with the fridge running. If this fixes my problem, I'll feel pretty fortunate that this has been my only problem.

[dougrainer]

IF the fuse blows, it is your 120 elements. Period. Replace them. Doug

[mxdad777]

I checked both heating elements and neither one show a short. After researching a bit, I kept reading about the Thermistor. I decided to check the ohms on it and there is no reading at all, it's just open. It's currently 60 degrees at my house so from what I've read I should be getting a reading somewhere between 12.1 and 13. So obviously my Thermistor is bad, but could that be what's causing my AC fuse to blow? I could see it blowing a fuse with a closed circuit, but not an open circuit. Any ideas?

[ScottG]

If it didn't blow the fuse after you removed the element from the circuit, it's the element that's bad.

[mxdad777]

Thanks for the replies. I did try unplugging the heating elements but when I did I received an error code. I don't recall exactly what the error code was, but it was something that made sense that there was a problem with the heating element (they were unplugged). It didn't blow the fuse, but I was thinking that because of the error the unit didn't try to turn on. After reading all of your replies, I'm going to check the elements to ground when I get home after work tonight. I'll let you know what I find.
Thanks again!

[dougrainer]

The Icemaker has a different 120 connection It is DIRECT and does not go thru the control board. The Fuse blows because one of the heating elements is grounded. Bad Element. Replace BOTH. Doug