Node-red temperature sensor with function node and relay

I want to use a DS18b20 probe connected to Raspberri Pi to control by aircon. I get the relay to switch on and off at the correct temperatures I want. The next step is where I am struggling... My requirements: Switch aircon off <= 20 (this works) Switch aircon on >= 25 (this works) when the aircon switches on above 25...keep the aircon on until 20 is reached, then switch off (this I can't get working) when the aircon switches off, wait for 10min {to protect the motor} (This I can't get working)

I have tried using a function node with the following code:

Any help here it be greatly appreciated...I have tried doing the same with switch and change nodes, but I can;t get the delay portion working then or get it to stay on to cool down till 20.

So in order to get this working you need flow context variables to store the state. I have created below example flow for your problem which makes use of the following 2 context variables:

• aircon_is_on : is a boolean indicating if the aircon is currently switched on or off.
• aircon_last_switch_tms : is a timestamp (expressed in number of milli seconds since 1970) of the last time the aircon has been switch on or off.

The details of the flow you can find here below.

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kr Jan