Polyscience chiller malfunctioning?

It’s a 7 litre with advanced programmable controller. Model AP07R-20-A11B
Temp goes up and down like in the photo. The scale is 4 minutes. Any suggestions?

What’s the alarm code?

It’s in ripen mode. Hook it up to your miner.


What kind of fluid are you using in the chiller? I’ve had strange temp fluctuations with non-recommended or contaminated fluids such as tap water in a pinch.

1 Like

No alarm code at all.

Nutherm 50 heat transfer fluid.

So that red alarms dot doesn’t take you to another screen? I’ve used a few different polyscis but haven’t seen that particular controller.

Only this. Our high and low alarm limits are no where near this.

1 Like

If you have the means, you can try to connect an external thermoprobe to the chiller. A quick search shows they make a pt100 external thermoprobe with what looks like an old ps/2 type connector but you would have to look in the manual to figure out if you could quickly wire in a spare to test. If you get a more stable reading with the external thermoprobe, your internal one is probably in need of replacement. If the readings still swing just as wide, something other than your thermoprobe is probably to blame.

1 Like

Agreed. Was thinking that. Thank you sirs

I would agree that that type of readout over that timeframe indicates a faulty sensor

One last question fellas…anyone familiar with the external temperature probe connector PLUG that Polyscience uses? I am trying to i.d. the connector.
Here is a pic.

I just took a look at the manual for the ap07r-20 and I’m a little confused. The image of the back of the chiller does have the port looking like you posted, but does it look like that on your actual chiller? A little further down in the manual it shows a pinout for connecting a 4 wire pt100 sensor:

If its more physically matching the p2 pinout in the manual, I would think it is proprietary?

I noticed that in the manual as well…but, after an hour of googling I’m pretty sure it’s a
S-video 4 pin Mini Din !

1 Like

Does it look the same when you put load on it? I agree that it could be a sensor issue but I wouldn’t expect it to be that “rhythmic”. If it flattens out when you load the chiller really hard, I’d suspect a PID issue. Could also be something repeatedly tripping like thermostatic protection on the compressor or a HPC from a clogged filter dryer or something (the latter would probably cycle more rapidly)


Looking at the wiring diagram, do you think the reds could be connected together and the blacks in order to use a 2-wire PT100 probe?

You can definitely try to see if the pid gets a proper reading. If anything I would think you may loose a little accuracy but the chiller would definitely be usable and would, hopefully, not cycle through temp ranges. I found this thread on another site claiming a 4-wire is identical to a 2-wire just with setup in a less crude fashion than this:

Some references:

I don’t think you will hurt anything trying this out, (connecting the 2-wire to a 4-wire connection). Its essentially plugging in a resistor and measuring the voltage drop across it.