Ranco temperature controller question?

[Allekornbrauer]

Hello I have 5gal of water in my fermenter that I am testing with my new dual ranco temperature controller. The reason I am testing it is one my use refrigerator an 2 to get to know my new brewing equipment. Well I have the controller in a Thermowell am hook up to the refrigerator but here the confusing part I have my controller set to 70f with a 1f differential but the temperature readout on the controller itself say it’s at 67f should I use a heat source to get it to the 70f were my controller is set at an also the refrigerator is in my apartment.

[Charlie]

In winter I like to set the cool side to 68 with a 2 degree differential (cooling kicks on at 71, pulls it down to 68, and shuts off). I set the heat side to 68 with a 1 degree differential, so it kicks on at 66 and cuts off at 68. That way they don't fight each other, and I keep the brew at my preferred 68-69 F temp range for ales.

Charlie