Nova Kool Frig Wiring Problem?

[FlyFishinRVr]

Originally Posted by Pahaska

I have a 1k potentiometer on my desk that will be installed on the fridge the next time I pull the refrigerator for any reason. That will allow me to boost the cooling a bit in our 100-degree Texas summers and dial it back a bit in cooler weather. It should help in keeping food in the safe range in century temperatures.

John you probably know this already but make sure your pot has a sufficient current rating for that circuit. From Sitchie's pic, it looks to be pretty hefty....

[FlyFishinRVr]

Originally Posted by Land Stitchy

Frig held steady all night at 36 degrees. Of course the coach is static in the driveway. This is a pic of the factory unit that I removed. Tried to read it with my tester but I think the short is giving me inconsistent readings - maybe something in the 500 range?
Will post again this evening after my next call with Nova Kool.

Any chance you can cut away the sleeving and read the colored bands around that resistor? That will tell you the value, and there may also be a marking on it with the current rating.

[Land Stitchy]

Cut the sleeve off but can't see anything without taking it apart. Don't want to do that until I talk to Nova Kool. I went to the business next door that specializes in electronics. They put it on their meter and said it was 550 ohms.

Just got a report from home. The frig hit a low of 35 degrees this morning but is climbing slowly as the coach heats up from the Florida sun. Hot day here and there is no shade in my driveway. Frig is now 51 degrees and 97 degrees inside the coach according to the air conditioning panel. Compressor is still running.

I assume this temp climb is related to the lack of insulation and not the missing resistor. The frig is still sitting on the sink countertop. Under normal conditions I would only have the frig running with food inside while we are on a trip so the inside temp would be comfortable with the air condition running.

[Pahaska]

With 550 ohms, the compressor should be somewhere around 2750 RPM. With no resistor, around 2000 RPM. With your larger fridge, it is not surprising that it is not holding temperature with no resistor in the circuit.

Sitting on the counter, there is no chimney effect to carry heat away from the coils. It should do better in the cabinet.

[Land Stitchy]

Just spoke to Nova Kool to report the findings. A defective resistor appears to be the root cause.

They are mailing me two resistor assemblies; black shrink for 550 ohms (what I had originally) and red shrink for 1500 ohms. He said I should probably go with the red given the Florida heat. The trade off is battery draw; he estimated 4 amps vs. 5.5 amps. Since I am not boon docking or overly concerned with battery conservation it sounds like the red pill is right for me.

One last shout-out for Nova Kool. They answered my call every time and Jim was on top of helping me out. They maintain my original 5 star rating.

[FlyFishinRVr]

Originally Posted by Land Stitchy

Just spoke to Nova Kool to report the findings. A defective resistor appears to be the root cause.

They are mailing me two resistor assemblies; black shrink for 550 ohms (what I had originally) and red shrink for 1500 ohms. He said I should probably go with the red given the Florida heat. The trade off is battery draw; he estimated 4 amps vs. 5.5 amps. Since I am not boon docking or overly concerned with battery conservation it sounds like the red pill is right for me.

One last shout-out for Nova Kool. They answered my call every time and Jim was on top of helping me out. They maintain my original 5 star rating.

Great to hear.

Get 2 more house batteries (standard on the '19's because AS finally realized the big fridge in the GT needs more juice) and you'll never notice the extra draw.

[Titus]

I too am impressed with the support that Nova Kool is supplying. Perhaps the GT installation is better than mine, but I have seen several posts saying that the installation is poorly done and provides no chimney effect. But chimney effect or not it appears that you will need some resistor to speed up the motor. A variable speed motor, via a potentiometer, is an interesting idea. It would let us speed it up when we add warm food/beverages. But we seldom add more than two at a time and thus have never run into a problem. We were in the desert earlier this year but I didn't notice a problem with the food not being cold.

[FlyFishinRVr]

Originally Posted by Titus

I too am impressed with the support that Nova Kool is supplying. Perhaps the GT installation is better than mine, but I have seen several posts saying that the installation is poorly done and provides no chimney effect. But chimney effect or not it appears that you will need some resistor to speed up the motor. A variable speed motor, via a potentiometer, is an interesting idea. It would let us speed it up when we add warm food/beverages. But we seldom add more than two at a time and thus have never run into a problem. We were in the desert earlier this year but I didn't notice a problem with the food not being cold.

How about a thermistor? As the temp inside the coach goes up, so does the resistance (PTC variety), and therefore the motor speed. A quick little circuit that limits the max resistance so the motor doesn't go crazy and a bit of calibrating and voila!

P.S. I bet everyone with a NovaKool could benefit from something like this, so if the NovaKool dudes are listening, there's a way to make your product even better. And for the entrepreneurs in the room, there's an idea that would be simple to make and you could sell a bunch of them.....

[Land Stitchy]

Might even make it on a Wachuko list which is better than a QVC endorsement.

[Pahaska]

Originally Posted by FlyFishinRVr

John you probably know this already but make sure your pot has a sufficient current rating for that circuit. From Sitchie's pic, it looks to be pretty hefty....

The resistor (and later the pot), are in the thermostat circuit with currents in the milliamps, not in the compressor feed. Per the Novakool manual, the control current is 5ma with no resistor and 2ma with the maximum resistor of 1523 ohms. The more resistance, the faster the compressor runs. Not much chance of burning out a pot with those currents.

[FlyFishinRVr]

Originally Posted by Pahaska

The resistor (and later the pot), are in the thermostat circuit with currents in the milliamps, not in the compressor feed. Per the Novakool manual, the control current is 5ma with no resistor and 2ma with the maximum resistor of 1523 ohms. The more resistance, the faster the compressor runs. Not much chance of burning out a pot with those currents.

Yep, no worries there. I'm a bit surprised at the size of resistor they used (physical size which is typically indicative of its current capacity) but I guess it's what worked best with their spade connector setup.

I may get a few PTC thermistors from mouser and mess around if I have nothing better to do (HA!!!). The little fridge in the Lounge doesn't really suffer from ambient temps like the big GT fridge, but hey, who doesn't want their beer a little colder on a hot day!

[Land Stitchy]

Got the resistors from Nova Kool yesterday. Installed the red one. Pretty simple to put it all back together. So far it is a steady 44 degrees. The final test will be driving with bumps this weekend.

I think this is case closed.

Just in time to open a new one on the BIM.