I am a new proud owner of a 2002 La Cimbali M21 Junior DT1 that I purchased on Ebay. I am in the process of trying to evaluate the machine and do an initial cleanup and have run into a couple intermittent issues that are somewhat frustrating. The unit is plumbed in and I tee'd the connection off my cold water line for my sink. I can be pretty sure the unit has water pressure since my sink has full water flow.

When I first turned on the unit, the fill light came on. Thinking it could be a fluke, I turned off and unplugged the unit and flushed some water through my faucet. This appeared to fix the problem. The unit heated up and I was able to get flow of steam through the steam wand, the group, and the hot water head. I even brewed 3 batches of espresso double shots. They were pretty decent, but the machine needs some tuning. Milk frothing was also no problem.

I took a break with the machine on and came back about 20 minutes later. I did some more flushing and was starting to try and figure out how the buttons were programmed by running several shots. I was not too concerned about wait times and after pulling a couple the refill light came back on and stayed on. You could hear the pump running, but it did not seem to fill. After a while, it timed out to the flashing red light on the level sensor. I tried to reset again to see if that would work like the first time. This time, there was no such luck. The pump just kept running until it timed out.

I restarted the system and decided to run a test to see the amount of water in the system. I found that the group head was not activated by the front row of buttons, but I could pull water through the steam wand and hot water attachment. I was able to pull at least 4 liters out with no loss in flow rate (in other words, I could have pulled more). I actually measured the flowrate during the last liter to be 0.75 L/min. I am not sure if that correlates to the pumping rate of the water coming in. Since I know the boiler size is 2.5 L, it seems like the boiler is able to pull in water from the supply. The water was warm, but not boiling (no steam) and so I think it was heating since that would be necessary for the water to be warm while I am pulling it out at a high rate.

My first thought is to think that the level switch is malfunctioning and showing that the boiler constantly needs water. In looking inside the unit, I found the level switch on top of the boiler and it was not connected to anything. That side of the boiler is a rat's nest of wires and there is one loose that would fit it, but it is also connected to one of the heating elements. I am not sure how the level sensor works, but it seems a little odd that I would connect the same wire to both the heating elements and the level switch. I have tried to get drawings of the wiring harness, but haven't found any.

I am running out of ideas on troubleshooting and places to turn. Being adventurous, I would normally probably try to tear the whole thing down and clean it out and descale just to make sure nothing is clogged, but since I am trying to evaluate the unit somewhat quickly I wanted to see if anyone might have run into a similar problem, might have ideas, or might understand how the level sensor works and wires into the controls. Anything anyone might be able to help with would be of assistance.

Just to update, I have tried connecting both the circuit connected to the heating element and a loose ground that was also around (obviously not at the same time) to the level sensor. The problem does not change. The pump just keeps running and then times out. I tried removing the level sensor and found no evidence of scale.

BPilgrim,
There are several others on here that have a machine closer to yours than mine and hopefully they will chime in. I have a la Cimbali M29 and have found from reading several Cimbali posts that there are lots of similarities among their machines. I had a similar problem when I first hooked up my used but new to me machine. For mine I had scaling that clogged the fill line. I would follow your water supply line fitting by fitting and see where your have a clog. If you didn't have a clog, your boiler would be over filling. My clogged fitting was an in line screen nested internal to a brass fitting. Also, if you can attach a picture of the connections in question, I'm sure someone can help you out. You can also do a search for posting by Ken Fox, he wired in a PID and a few other things to his Cimbali and some of his post might have a picture that helps.