Bev-Air DD68 Icing Over

[gregariousness]

my roommate and i recently bought an old beverage air dd68 kegerator off craigslist. the kegerator got down to 28-29 or so when we had it on at first, but the compressor never kicked off and after a few days the temperature started to rise. we turned it off and the cooling unit had frozen over, so we let it thaw and dried everything. this cycle happend twice before we bought one of those external thermostats people use for freezer to kegerator conversions, this helped by turning off the kegerator when it got down to temperature (we had the new thermostat probe in alcohol). this worked for a while, but eventually the overall temp began to rise, so the thermostat won't cut off the power any more. we have installed 3"towers over the 1" holes, but were pretty certain there isn't any air flow there.

any ideas?

i've attached a picture for your viewing pleasure... this is before we put the new 3" towers on. we currently have a friend working on some fun F#CK M!CH*G@N themed art and will post a pic when he is finished.

thanks.

[THE ICEMAN]

You are trying to run the unit too cold. Your statement that the compressor never shut off is a clue & the reason for the evaporator to freeze up. If there is no air flowing through the evaporator due to ice buildup, the unit will not cool properly. The only way those units can defrost themselves is the 'off' time of the compressor.


THE ICEMAN

[gregariousness]

i guess i forgot to mention that. we have the external themostat set to 36 degrees F.

[THE ICEMAN]

With the external control you are only sampling air temp & not the temp of the evaporator coil. Therefore, depending where you have the temp sensor inside the unit, the temp of the unit can vary a great deal. Once again, if the compressor does not shut down because the temp control has not told it to do so, then the evaporator will freeze over. Try moving the temp control sensor to different locations.


THE ICEMAN

[gregariousness]

ok, will do, but they external control thermostat probe is in an enclosed plastic jar of alcohol, to get more of a liquid temp versus an air temp. where would you sugest placing this?

[hobster]

I have a DD-58 and when I first got it I set it at 4-5 on the dial...and it froze over. Set your dial at 6 and see what happens.

[pvs6]

gregariousness, here's what I read so far correct where I'm wrong and fill in missing pieces and you'll get to the root faster.

the kegerator got down to 28-29 or so when we had it on at first, we turned it off and the cooling unit had frozen over, so we let it thaw and dried everything. this cycle happend twice before

Was the 38-39 temp. of 2nd pour of beer or probe in water \ air \ alcohol in the keg box?
Why did you turn it off? How did you know that chill plate iced over? Were you opening the door a lot to marvel at your keg and see how's it doing in there?
By cycle happening twice before you mean on that 1st. keg when you got it?

{we bought one of those external thermostats , this helped by turning off the kegerator when it got down to temperature] {so the thermostat won't cut off the power any more.}

So the controller did in fact shut off compressor? Then as it ran for 2 day and started getting hot again, at that point the compressor just ran all the time again.

Any compressor that runs for 2 days straight is bound to get blazing hot and that could restrict the heat transfer off of the heat transfer coils in back. Where is your unit positioned? Under-bar, or up tight flush against a wall? Got to have good air flow to the back of unit for the long haul. If it's iced up 3 times now as I read it and you haven't been opening the door then open it now and inspect the gasket for leaks. How long have you had it, did it ever work right and then when did the issue start ie: how many and what size kegs did you run through before issue?

[TomK]

What did you have the BevAir's temperature control dial set to before you added the external controller?

[gregariousness]

to answer hobster and Tomk: we tried all the settings of the beverage air thermostat, the condencer never shut off, even on the warmest setting.

[gregariousness]

pvs6: when i said the temp got down to 28-29, i was refering to the air temp. we were able to see a bit of ice forming through the grate inside, so we turned it off to melt the ice. about a quart or so of water ended up melting. and my the "cycle" i ment that it froze over then we melted it. then it froze over again. yes, at first the external controller shuts off the compresser when it gets down to temp, but after a while it doesn't turn off anymore and ends up iceing over and geting warm. its kinda up against a wall right now, and we have had it for about a month, we still havn't finished any kegs yet, but there are some about to blow. theres 2 halfs and 2 6ths in right now. one of each is almost empty.

thanks for the comments everyone.

[pvs6]

The very first thing you need to do is get 2nd pour temp. ie: real beer temp. this will be different than your measured air temp. and is the only temp. you should report. Ice is a pretty good insulator thats why Eskimos build igloos to live in and keep out the cold. Once your chill plate freezes over inside cooling is lost because the ice blocks heat exchange. You said it worked at first and after defrosting too until it iced up and then the compressor runs fultime but doesn't cool. Therefore it looks like your problem is the chill plate ices over. When the compressor is running the chill plate surface gets to 27 F, 5 degrees below freezing. If the chill plate stays steady at that temp. as it does with the compressor working fultime ice will surely form. That ice is the frozen water that is in the air inside of your sealed keg box once the door is closed. Once all that air inside gives up all it's water vapor to convert it to ice on your chill plate there crosses a point where no new ice can form for lack of water. Two things that can promote ice forming are opening the door a lot and an air leak letting room air in. You said the unit is old and used so the rubber gasket that seals the door is suspect, if it's old and doesn't seal completely then wet warm room air gets in to turn to ice and lower cooling. Move your unit at least 4 inches from the wall and 6 would be better. The back needs ventilation to do it's work.

[THE ICEMAN]

ok, will do, but they external control thermostat probe is in an enclosed plastic jar of alcohol, to get more of a liquid temp versus an air temp. where would you sugest placing this?

Take it out of the alcohol & place it on the exterior of the fan guard, the air intake of the evaporator, this will sense the air temp of the box.

Ice is a pretty good insulator thats why Eskimos build igloos to live in and keep out the cold. Once your chill plate freezes over inside cooling is lost because the ice blocks heat exchange.

He doesn't have a unit with a "chill plate". He has an air over evaporator with fans providing airflow. If you had bothered to read this thread you would have seen that I already warned him that if the air is not flowing THROUGH the evaporator due to ice buildup, the unit will not cool properly.


That having been said, again, there could be another reason for the ice buildup, but try moving the sensor first before we get into that.

THE ICEMAN

[gregariousness]

thanks guys

ha, yea i realize that ice is a good insulator... thats why i have defrosted it several times in a effort to keep the ice out.

i will be moving the temp sensor and the kegerator away from the wall and then will report back.

thanks again.

[pvs6]

don't be curt

He doesn't have a unit with a "chill plate". He has an air over evaporator with fans providing airflow. If you had bothered to read this thread you would have seen that I already warned him that if the air is not flowing THROUGH the evaporator due to ice buildup, the unit will not cool properly.

Ice man thanks for coming to the rescue, I think what I was trying to convey was that ice build up any where reduces cooling performance. The chill plate slipped in because I think in terms of my own kegorator. Your wrong thought I do read all threads I reply to from start to finish and will often ask for an update private after the threads gone dead. We're all just trying to help.