The idea is to be able to display temperatures in both Fahrenheit and Celsius by flipping a switch. Most all temp meters come displaying temps only in Celsius. I am more used to seeing temps in Fahrenheit but also understand that Celsius is more accepted worldwide so I wanted to be able to see both easily.

Credit MultiPlayCity for the 'how to' on changing a meter to display Fahrenheit in this article. I used this to figure out how the two temps are wired.

Be advised that there are more than one type of board in these LCD temperature meters, depending on the manufacturer. (CompuNurse, Senfu, Enermax Etc.) The one that were in mine are marked 9943 on the board. The same type of mod should be possible with other boards but you will have to figure it out.

I used an Enermax dual temp sensor for this project. It has two temperature meters and a bay mount that can hold a hard drive or two 80mm fans.

The first thing to do is remove a temp sensor from the unit and then, carefully open the back of it and remove the board. Be careful with the LCD screen and the little rubber strip that is attached to it. Put it somewhere safe.

Temp sensor circuit board (click for bigger pic)

Now look at the board. There are three sets of tiny pads that have connections made on them with solder blobs. The first step is to remove the solder blobs that are there. You can use desoldering braid, a solder sucker or a desoldering iron. I used a cheap desoldering iron from radioshack that worked well. Make sure the sections of the pads have no solder connecting them.

Each of the sections of the pads are connected to a drilled solder pad. Lets mentally number then like in the above picture. Numbers 4 and 5 actually have more then one connection if you trace it and see where its going.

Board wired (click for bigger pic)

Next solder a length of wire to the each of the drilled pads that are connected to pad sets like in the above picture. These wires will go to a switch to change the sensor from Fahrenheit to Celsius.