Jura 24029 Automatic Hot and Cold Milk Frother, Stainless Steel, 650 W, is no longer heating milk (still frothing)

Oh, how long are you using that frother machine already? Isn't that a factory defect or what? Try to contact the customer service of the company. That would be the best thing to do.
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There may be an issue with the milk you are using if your Keurig K cafe frother is only heating milk and not frothing it. There is nothing wrong with your frother.
You must consider changing the milk you are using and hopefully, your problem will be solved. Read this article for complete details on fixing the frother.
Keurig frother not working

I have tried tilting mine slightly, just a 20c peice under one edge of the base put enough of a lean on it to make the milk froth. Shouldn't have to do this, I know. I am having similar issues becasue I don't think I should have to alter the unit. Mine is 2 weeks old.

Had this exact problem a few times on a cleaned well maintained milk jug top with an ESAM5500M. Delonghi 'repaired' it by sending a new milk jug frothing top.

It's caused by milk fat deposits, the frother part on the milk jug may look clean but deep inside it's not. I clean mine with pipe cleaners, detergent and hot water and still it wouldn't froth.

The problem re-occurs for me every 6 months or so. You could buy the milk fat remover solution to clean it. Personally I just boil the whole milk jug frother in detergent and the again in descaling solution, that's fixed this problem twice now, although I think it will eventually corrode the 'o' rings on the frother, still cheaper than buying a new frother part each time though.

If it still doesn't work after that, the only other reason for this problem I found mention of was caused by a broken rubber seal where the milk jug fits to the machine. It's most likely to be milk fat deposits inside the frother though.

Means you are not heating your milk, the frothing milk will be cold (for iced drinks) because you have held the button down longer than normal. Usually it takes 5 Seconds for the blue light to go on. try turning it on or pushing the button faster, It should turn on red, for heated and frothed milk.

We bought a Nespresso Milk Frother in 2010 for $100. The frother is the same one that comes with the Citiz machine but is a stand alone model. It froths soy milk very well. The less soy you put in it, the more froth you get but even if we fill it to the max line we still get a reasonable amount of foam. We use Silk brand soy milk. I have no idea if foaming is impacted by atmospheric pressure but it may be a factor to consider if you are using all the same factors as us but not getting great results. We live at a higher elevation Calgary, Canada in the foothills of the Rocky Mountains.

they make one that has the option of frothing milk hot or cold. Blue light is cold. Red light is hot. The red light will always heat the milk. To get to the blue light, you need to hit the button twice.( First will go to red)

It doesn't froth because the air hole in the frother has become plugged with dried milk (cream). There are two types of frother - old one was a black rubber nipple with a stainless 2-3inch air tube rising above the milk. The plastic insert has a pin hole (really about the size of a straight pin!) that clogs. Use a sewing needle or straight pin to clear it.

The stainless steel cover has a very small hole near the top. The hole allows a venturi action - meaning air molecules are entrained with the steam flow to increase the affect. Milk will clog the hole, but warm water and a guitar string, cheese wire, even a staple - something thin - will work to clean it out.
After frothing either clean the entire stainless steel piece or at least occlude the end at the same time as shooting through some steam. I usually use a kitchen sponge with the abrasive pad attached. The pad helps insulate the heat and provides the necessary resistance to force any milk out the small hole.
Yes, I hate living with this also. In fact I am considering machining a different steam tube assembly.
Red