Refrigerator fan electrical issue

I “THINK” my refrigerator fan issue has been fixed!!

My Dometic RM8501 refrigerator comes equipped with a small 12v fan at the lower left of the unit.  It blows upward across the fins to cool them. It is operated by a thermoswitch located on the main tube in the upper right.

  I have been trying to add an auxiliary fan in the upper section to help remove the accumulated hot air and increase refrigerator efficiency. After wiring in the second fan,every time they ( both original and newly installed) came on, the refrigerator would turn off and the alarm light would turn on.

 I went through about a week testing every potential combination of fans, thermoswitches, 12v  terminal blocks,ec. I was plugged in to shore power at my shop. I posted here and got some good ideas. I watched YouTube videos, I called friends with RV’s, I talked to Dometic Tech people 3 times and was going crazy.

 I could never make the existing wiring work if adding an additional auxiliary fan in the upper rear refrigerator compartment.

 The wiring was different from 2 other friend’s Rpod 179’s, but they were newer and different from each other actually.  In my case, the two wires(red/black) came from inside the polyswitch--no visible connection  available , could only cut and splice new wires.  The red wire came from the poly switch interior to the thermoswitch-then continued to the fan. The black wire came from the interior of the poly switch and went straight to the fan.  That seems to be straight forward. It “SHOULD” work to just cut an existing wire and splice in a new wire. But it doesn’t!

 Maybe that was too much voltage when they came on? Nope, according to Dometic the original fan is .46 amps and the new fan is .32.  I also checked the shunt and when the fans came on, it showed a .8amp drain.

 Ultimately, the Dometic tech people sent me several web addresses for service and technical manuals. I found a wiring diagram that showed the fans were directly wired from the 12 v terminal block on the back of the refrigerator unit and NOT through the polyswitch. I simply capped off the original red/black wires from the polyswitch and rewired it per the drawing.  I added a red and black from the +/- terminal block–red to the thermoswitch input and black to the fans. Add a red wire from the thermoswitch output to the fans that are wired together. Now, when the thermoswitch closes, all of the fans come on together and the refrigerator continues to cool.

 I’ve tried it most of the day with both propane and shore power and so far, everything works as expected.

Finally.

  Travel safe and often

Vann