Dometic CoolFreeze (CF-50) Problems

Casey

As some of you know, we are cruising in the Chesapeake Bay (near Easton, MD).

Earlier this morning I noticed that the three year old Dometic freezer temp was 27degrees. It is usually at 16degrees in the morning, if the power supply is uninterrupted.

I unplugged the freezer and replugged it. Power came back on and it showed 27degrees. At the time none of the Power/Set/Up/Down buttons seemed to do anything. We had access to 110V so I plugged it in to shorepower. Still no change.

There is an "Emergency Override" switch situated between the 12V and 110V plugs. Online researching suggests this switch overrides the thermostat and simply(?) permits the compressor to run. Mary can hear the compressor run (I cannot). Hopefully, this will mean the unit is still cooling and in a couple hours it will show a slightly cooler temp.

After about :30 we rechecked the control switches and the On/Off button worked again, and pushing the "Set" button showed the freezer is set to 16degrees (then it switched back to the ambient temp of 27degrees).

Two nights ago we had a torrential rain and the freezer got quite wet sitting in the cockpit. This morning we removed the insulated cover, set up some shade, and have a 12V fan blowing on the cooling unit (to help dry out anything that might have gotten wet).

Our "plan" is to check it occasionally and HOPEFULLY see the ambient temp come down to 26/25/24/etc. Once we establish that the compressor is actually cooling we'll switch it back to the "Normal" mode.

Any other ideas or suggestions?

Best,
Casey&Mary
Temp's today are supposed to be 89 and 97 tomorrow ... not a good time to have one's freezer hiccup.

'o cino · Posted: Mon Jun 22, 2015 11:07 am Post subject:

We had a Dometic long ago, and it's upper functional range was about 92-95f (outside temp), where you would notice a decrease in operating efficiency. The compressor would work fine, it's just a design limitation. I'm in Waldorf, and feel the heat too ... and the wicked lightning shows as of late. Was your unit in the cockpit with sun exposure?

thataway · Posted: Mon Jun 22, 2015 12:18 pm Post subject:

Getting wet is not good, since the circuit boards are not potted. You are correct about the over-ride, and that is what I did last summer, when I had the problems with the thermister. It could be that yours is also having thermister issues, which is a known problem--and for which Dometic gave me a new unit (and I just sent them back the serial number of the bottom, and put a new thermister in the bottom or side of the inside box.

I believe that Casey knows about the insulation issues--and does as we do--use the "jacket" around the unit, and an extra foam piece with aluminum foil to help with sun issues. We find that the unit will generally keep things well below freezing even in the high temps of Lake Powell--it may not be at zero, but will stay in the teens or low 20's.

There is information about repairs and issues, in some of the off road forums.

I have also acquired a digital freezer thermometer, so I can monitor the exact temperature in the the box--I find that the digital read out is sometimes a bit off.

Keep us appraised. I may have the supervisor of technician's e-mail, and will look for that, if drying out the unit does not help

Casey · Posted: Mon Jun 22, 2015 12:19 pm Post subject:

It is in the cockpit, but mostly protected by the Bimini from direct sun. We usually keep two white PFD cushions on the top and the freezer sits on some Dri-Dek squares (for circulation).

Casey · Posted: Mon Jun 22, 2015 12:26 pm Post subject:

Thanks Bob.
If you find the tech's name and number, pls forward it.
Looks like there might be a 'thermistor in our future.
Best
Casey&Mary

thataway · Posted: Mon Jun 22, 2015 1:23 pm Post subject:

Casey,
I cannot find the gal's phone number or name, (I'll will look further later today.) I did write her a "thank you" note, but I must have written it by hand. The receipt for the new unit did not have a name on it.

I found customer support worthless. This gal basically sent a new unit, since mine was out of warrantee by 2 weeks when we found the problem. There was no offer to repair, and I don't think that Dometic repairs them.

Here is the link for the Thermister, plus some other links for repair, and issues:

http://www.way-cold.com/WaecoThermistors/singlewaeco.htm

This outfit has other repair parts, including the fan. I did take our old unit apart, and decided it was too much of an issue to put the new thermister in place under the bottom of the liner, and just taped it to the wall, where it works fine.

Sunbeam · Posted: Mon Jun 22, 2015 2:07 pm Post subject:

I have a CF-50 too. A friend has a CF-40 in his car, and I borrowed that to take a little trip. I did find that the unit would not hold a low temperature when ambient was over 90º (and this was dry heat - not sure if moist heat might make it worse?). I then noticed that in the Dometic manual they do note that the normal coldest temps officially cannot be reached when ambient temp is over, I forget, but I think it was 90-somethingº F.

Still, I never had the odd control issues you did, but just rather I had it set at something like 10ºF and it couldn't cool below around 28º or something. Like Thataway, I use a separate thermometer ("indoor/outdoor" type) and keep the display where I can see it (in this case from the driver's seat in the car). The displayed temp is not all that accurate from what I can tell.

I'm trying to remember if I did have any odd issues (besides the inability to get down to a low temp) in the extreme heat.... I don't think so (got a low battery shutoff once, but that's cause there was an auxilliary batt hooked up for running when the car was off, and it was a bit limp). It was up to around 115ºF outdoors when I was using it in the car. So of course air-conditioned while I was driving, but then horribly hot while it was parked (I was at the boat, puttering around).

In summary, I have found that - true to Dometic's warning in the manual - the unit cannot cool to its rated capacity in very hot weather; but I didn't have the odd switching/power issues you did, so maybe that has more to do with it getting wet that time in the rain.

Casey · Posted: Mon Jun 22, 2015 7:23 pm Post subject:

Well, we're making progress - sort of ... maybe , I think. Hmmm

We emptied the freezer and defrosted it. When empty we reconnected to 110V and watched the temperature progress downward for a few hours. Initially it showed 53degrees, then 51 ... 31, then eventually 14degrees. Yeah! We then reloaded the freezer with the still-frozen items.. Temperature went back up to 29. A few hours later it was 31. Puzzling. This was with the Emergency Overrride engaged. My guess is that the Emergency Override circuitry may have some sort of time-limited feature (that we exceeded?). My 'plan is to use the Normal mode and watch it until we go to bed. If there is no change we will reactivate the Emergency Override and recheck temperature in the morning.

Stay tuned!

Best,
C&M

Casey · Posted: Wed Jun 24, 2015 6:10 am Post subject:

When we got underway yesterday morning the freezer was at 22degrees. By the end of the day it was showing 20degrees.

Last night we had spectacular thunder/lightning with extremely heavy rain for an hour as a front moved through. We knew the bad wx was coming so we rigged a large golf umbrella over the freezer to give it some rain protection and left the umbrella in place over night. This morning the temperature read 11degrees. Yeah!!

Takeaway: looking back on this whole episode I think defrosting the freezer back on Monday may have been an important step. I can't explain it, but that seems to coincide with when we began getting colder temp's again.

Anyway - things seem to be back to normal for the time being.

Best,
Casey&Mary

thataway · Posted: Wed Jun 24, 2015 8:56 pm Post subject:

Casey,
The temperature registered is via the thermister--and this may explain the paradoxical temperature changes. This is why I went with direct readings in alcohol (so it would not freeze). I don't have all of the numbers, but even in the new refer, it was at odds with the temp measured in the alcohol. (We used gallon jugs of water as the "frozen" load--and our experiment was not too different than what you are experiencing.

I assume that the unit is running all of the time. You might try and see what happens when you go back to temp settings.

Casey · Posted: Thu Jun 25, 2015 8:01 pm Post subject:

Freezer is working fine now (set at 11degrees). Problem seems to have
dissappeared (but doing a complete Thaw seems to have helped too).

Best,
C&M
At Langford Bay Marina (off the Chester River (MD)