Daily Anomaly in Temp Cycle

Troubleshooting
1

So I have noticed that about every 12-14 hours there is an issue with the refrigerator cooling cycle. The fridge takes about 30-45 minutes to engage the compressor. I thought it was because the fridge I am currently using is old and beginning to die. It could still be that but I’m not certain because of the error I am receiving and because it’s so cyclical in nature. See attachments below for screenshots of the graph showing the temperature spikes.

Here are some of the debug messages in stderr:

“Listening on LPF/wlan0/00:0f:13:37:20:c3
Sending on LPF/wlan0/00:0f:13:37:20:c3
Sending on Socket/fallback
DHCPRELEASE on wlan0 to 192.168.1.254 port 67
Feb 04 2015 06:10:14 Arduino debug message: INFO MESSAGE 18: Negative peak detected: 5.7, estimated: 6.0. Previous cool estimator: 0.459, New cool estimator: 0.459.
Feb 04 2015 07:48:59 Arduino debug message: INFO MESSAGE 18: Negative peak detected: 5.9, estimated: 6.1. Previous cool estimator: 0.459, New cool estimator: 0.459.
Feb 04 2015 09:02:28 Arduino debug message: INFO MESSAGE 18: Negative peak detected: 5.9, estimated: 6.2. Previous cool estimator: 0.459, New cool estimator: 0.555.
Feb 04 2015 10:09:50 Installed devices received: [{‘a’: ‘285A24B4050000B2’, ‘c’: 1, ‘b’: 1, ‘d’: 0, ‘f’: 9, ‘i’: 0, ‘h’: 2, ‘j’: 0.0, ‘p’: 18, ‘t’: 1}, {‘a’: ‘28A9F4B305000041’, ‘c’: 1, ‘b’: 0, ‘d’: 0, ‘f’: 5, ‘i’: 1, ‘h’: 2, ‘j’: 0.0, ‘p’: 18, ‘t’: 1}, {‘c’: 1, ‘b’: 1, ‘d’: 0, ‘f’: 2, ‘i’: 3, ‘h’: 1, ‘p’: 2, ‘t’: 3, ‘x’: 1}, {‘c’: 1, ‘b’: 1, ‘d’: 0, ‘f’: 3, ‘i’: 4, ‘h’: 1, ‘p’: 5, ‘t’: 3, ‘x’: 1}]
Feb 04 2015 10:09:50 Available devices received: [{‘c’: 1, ‘b’: 0, ‘d’: 0, ‘f’: 0, ‘i’: -1, ‘h’: 1, ‘p’: 6, ‘t’: 0, ‘x’: 1}, {‘c’: 1, ‘b’: 0, ‘d’: 0, ‘f’: 0, ‘i’: -1, ‘h’: 1, ‘p’: 19, ‘t’: 0, ‘x’: 1}, {‘c’: 1, ‘b’: 0, ‘d’: 0, ‘f’: 0, ‘i’: -1, ‘h’: 1, ‘p’: 4, ‘t’: 0, ‘x’: 1}]
Feb 04 2015 10:37:20 Arduino debug message: INFO MESSAGE 18: Negative peak detected: 6.1, estimated: 6.4. Previous cool estimator: 0.555, New cool estimator: 0.670.
Feb 04 2015 11:58:30 Arduino debug message: INFO MESSAGE 18: Negative peak detected: 6.1, estimated: 6.3. Previous cool estimator: 0.670, New cool estimator: 0.670.
Feb 04 2015 13:09:28 Arduino debug message: INFO MESSAGE 18: Negative peak detected: 6.0, estimated: 6.2. Previous cool estimator: 0.670, New cool estimator: 0.670.
Feb 04 2015 14:26:33 Arduino debug message: INFO MESSAGE 18: Negative peak detected: 5.9, estimated: 6.2. Previous cool estimator: 0.670, New cool estimator: 0.670.”

2

As far as I can see, there is no reason to look for the cause in how the actuators are driven.

Could it be that the sun shines through a window around these times?

3

Or perhaps your refrigerator has a mechanical defrost timer.

4

There is no sunlight hitting the fridge and I’m pretty sure it’s happening in the night as well.

5

What is a mechanical defrost timer? How does it work? It is at least 25 years old.

6

You got pics of the fridge

7

I can take some pictures tonight if it will help but I think that this is the cause of the anomaly. I typically ferment ales and so usually it takes much longer for the defrost timer to kick in because the fridge runs less because I don’t see many anomalies looking at my older brew sessions. Because the beer setting is 8.9C it is running more frequently and causing this to occur more frequently. Thanks for the help.