Need help to By pass thermostat [solved]

So the fridge I have is an English Made Lec. I am trying to papas the thermostat and create a switched fridge but am struggled to work out what should go where in terms of the thermostat. Apologies for the poor picture but what I have is.

A black cable coming from the compressor that has Brown, Black, green/yellow and blue.

The blue goes to the light everything else got to the thermostat.

The brown from the thermostat then splits off to the light switch and from the light switch the white cable comes back to the light (does the make sense)

Similar to mine - I believe you want to bridge the brown and black to switch on the compressor. Therefore, your relay should take brown and black as “inputs”, and be in the closed state when actuated. If you want the door light to keep functioning, you’d want to keep the brown cable going to the door switch before it hits the relay. Does that make sense?

  • nb. I accept no responsibility for blowing up your life.

@benbenson thanks for your help.

I think so the brown and black go into the SSR and if I want the light to stay on I need to spur off the brown before it gets to the SSR.

If I want to use the light as a heater would I simply replace the door switch with an SSR?

I think it would be best to run the door switch to the controller. I don’t have a brewpi spark yet but in the arduino model: you would simply run a wire from arduino pin 4 to the switch then back to ground. If not using a heater then use your second ssr to power the light. In my setup I have a separate relay to control the light so I can use it as a heater one day if I need to. Meaning a total of 3 separate relays. Now if you use your heat source relay to control the light, you will need to assign it as light and not heating. This way the light will turn on when the door is opened. And you will have to change the settings to use light as heater/

I’ve not got a heater for this one yet and I’ll actually be using it to keep beer at temperature for the time being so am I right in terms of using the SSR to power the light rather than the door switch.

I understand what you’re saying about the a4 pin but don’t know how I would connect that to the switch itself.

I would have to see the fridge to make the modifications myself. But the wires coming from the door switch would need to be removed from the light circuit. Then the switch will have 2 wires going to it. One wire would go to arduino d4 pin and the other will go to ground. I don’t rember if I had to change the inverted/non-inverted state of that pin. Then arduino d2 pin controls the relay for the lights. In this configuration brewpi can see the state of the door and control the light. then change the line on the settings page to use light as heater. All of this can be done without messing with the door switch but you lose the ability to log the door being opened of closed. Which may affect the set points of the software since it doesn’t know that you have the door opened only that a large temperature difference happened all at once. I have used a couple different methods of controlling and sensing door open/close with no noticeable differences in the way brewpi manages the set points.

In one test I used a relay attached to 5v power with its ground traveling through the door switch branching off discreetly to the arduino for door sense. Allowing the door and light to function independently of the software. But more parts are needed for this and an external 5v power supply is needed too. I left this design behind because of the extra parts and space and time needed to set it up. Finding it easier to let the arduino turn the lights on and off a simpler setup but there is a small lag between opening the door and the light coming on. But I’m just OCD about such things.

OK so all i want at this stage is the fridge to cool (bypassing the thermostat) and the light bulb to provide a tiny bit of heat.

I’m not overly fussed about it logging when the door opens or the light coming on when i open the fridge door.

I’ve uploaded some pics,

the last one being the door middle one being the door switch, am i right in thinking i can just put the SSR in the place of that switch?


Hoorah it works, it cools and the tiny little bulb is pretty effective at heating.

only one smallish electric shock that tripped the junction box, I never learn I should and you should make sure you turn the fridge off after you’ve tested it and are putting things inside under or out of sight. I am an idiot!

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