I just got my CW-3000 chiller hooked up and filled with Prestone anti-freeze. As soon as I turned it on the alarm was sounding. It’s filled with 2 gallons of anti-freeze, the fan works, the pump works, coolant is flowing and the display reads 20.8 C. Anyone know why it it might be in alarm? The only thing I can think of is that it came with 3/8" hose connections and I replaced them with 1/4". Could that do it? In the mean time I cut the wire to the speaker but the red alarm light is still on.
IIRC there’s a flow sensor in the back of the enclosure right where the hose enters it. Does anything look obviously wrong with it such as loose or broken wires?
I just set one up as well. I know there are a variety of CW3000 chillers but the one I received did have a manual with this diagram.
When you power up do you get a flash of the green light? If so they may have swapped the relay contacts NO/NC. You should get a blip on the red and alarm for a normal power on. I would also try to pinch the tube restricting flow to see if the green light came on.
If that doesn’t bear fruit next would be with power off ringing out the thermal switch and the flow sensor (which should be open when off). If the thermal switch is closed the next step would be to check for voltage while running at the relay coil. Watch to see if you can see or feel the relay engage. If not then jumper out the flow switch and thermal switch to see if the relay works.
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I should have added that the green light is on all the time as well. So I have solid green, solid red and alarm buzzer. But looking at that circuit, that shouldn’t happen. It looks like it should be EITHER green OR red but not both. So that almost seems like the relay is defective.
Does your CW3000 have the external contacts? Do they switch properly or opposite of the lamps? Could they have wired both NO to one and the NC to the other rather than one of each to lamps and external connector?
I had an issue with a CW-3000 as well and track it down to a faulty flow sensor. Or at least, I open the unit and test it every other device that I could, and could bypass the issue temporarily by jumpering two pins on the back of the unit in one of the circular connectors. This was months ago so I’d have to look to see what I actually did if you want to try the same thing. Obviously the longer-term fix is to figure out why it’s incorrectly behaving and address that, but if you need to use it and it’s annoyingly loud there should be a work around 
I’m going to have to do some troubleshooting to see if one of the switches is bad or what. In the diagram above, does anyone know what KM is? In the meantime I’ve cut one of the wires to the buzzer so it’s at least useable
KM is the relay that is associated with the contacts for the lamps/buzzer and external status.
*Edit:
I wondered why and found that Relays are called ‘K’ because IEC 60750 and IEEE 315 say so .
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