I’m replacing the thermostat in my coffee maker. It went bad and melted the connectors. This should be really easy but I can’t find the right connector and housing online. Part of my challenge is I don’t know the proper name.
Here’s what it connects to:
The male connector you see is 6 mm.
Here’s what I need to replace, only preferably with ones that aren’t melted. The first two images are with the plastic housing, the second two with it removed.
You don’t really need to replace anything. All the melted plastic is junk; throw that away. Clean up the fastons that’re crimped to the two wire ends so there’s no melted plastic stuck to them. Then simply clip them back on to the thermostat. Polarity isn’t going to matter. Wrap the result in hi temperature compatible electrical tape and you’re done.
If the connectors are too encrusted in melted plastic to reuse, or the wire insulation is melted too far back, clip off the current spade connectors and crimp on new ones. The amazon cite just above is them, but there are lots of places to get them. Auto parts places, a real hardware store, McMaster Carr, etc. Ideally you can find a pack of 10, not of 250.
A lot of times these connectors will fail because they overheat due to over current and poor crimps. The connector should be pretty darn tight on the spade. If it isn’t, close the opening with a pliers.
By experience (a few decades back) with these connectors is that you can never quite get the fit that they get when coming out of the factory.
If you really want to replace them, visit Goodwill or a similar thrift store and scavenge the parts you need. Or just toss it in the trash and buy a new one.
That connector looks pretty bad. It isn’t going to be just the thermostat failing that gets things hot enough to cause that. I would suspect the connector went bad and cooked itself. If both connectors are equally bad maybe the thermostat is partly at fault. Only one and the connector itself is the problem.
If a thermostat fails closed, there should be a thermal fuse in line with it to prevent the machine cooking itself and causing a fire. It should have opened long before temperatures were high enough to cook the connector. Some machines have a resettable fuse, others a one shot device. You may need to check it as well.
Coffee machines are a never ending source of such problems. Luckily, for most, parts are ubiquitous and common between many machines. For a common machine you could probably find an entire wiring loom as a replacement part.
Thanks all, “flag connectors” got me pointed in the right direction. I also appreciate the reminder to get high-temp connectors. The existing ones are pretty bad, and they’re easy to replace.
This is actually an espresso machine with two thermostats (107C and 145C) that are, according to what I could find online, wired together in such a way that a failure in one doesn’t always fail cleanly and instead causes the other to overheat. One commenter said if the espresso starts coming out too hot, replace the thermostat quickly because you have a few days before it all melts down. I didn’t do that, and indeed it went from “this coffee seems too hot” to “what’s that burning smell” in about three days.
The 145C device is the thermal fuse. It should only ever open once - and then need either resetting manually or replacing - depending on type. It is there to protect the system - it isn’t intended as a thermostat.
This is a problem with these machines. If a thermostat fails closed - which can happen by it welding its contacts closed internally, or other failure of construction, you are reliant on the boiler reaching the cut off temp of the thermal fuse. The machine should go dead at this point.
Where it may get complicated is if it is a single boiler machine with steam function. There you have the boiler running with two different temperatures, one to generate hot water for brewing, and the other to create useful steam for milk drinks. Or you may have a thermoblock doing the same thing but intended to provide instant hot water or steam.
More advanced machines dual boilers, or heat exchangers become more complicated.
It isn’t a good design. But has been with us for decades.
You know, I had a feeling it was going to be a Gaggia Classic.
One can see from the circuit, they have two thermostats, but they don’t seem to have a thermal fuse. Not great. The 145C thermostat is basically providing dual duty. Can’t say I’m impressed with this. It is a very basic design. You end up with a dry boiler being cycled up and down to an external temperature of 145C. Internally, this will kill the element.
If you had the urge there is a whole lot of stuff out there to tweak up and improve a Classic.
There is a separate 184C fuse - I think it’s #3 on the diagram. It’s blown as well, so I’m replacing that along with the thermostats.
I like to think I’d design this differently. But the Classic has been a workhorse for me with several years of trouble-free operation until now, so I can’t complain too much. Maybe a little…
