I have a 6-month old Intellichlor IC40 (V2.01 built July 09) installed on my pool.
The LOW Salt light stays on and the Cell is off (no CL being produced). EasyTouch diagnosics show zero salt level.
Salt tests using new Aquacheck strips show salt level is 3840ppm. Took sample to Pool store test. Their test showed 3900ppm.
Acid washed the unit (4qts water/1qt acid) - - no fizzing - - cell was clean.
Put the IC40 back on and still have the Red LOW salt light on.
This morning I called Pentair tech support (Thursday 4/1/2010) to ask them if I should field calibrate the unit. The tech guy said that you can NOT field calibrate any IC40 after V1.6.
He asked me to acid wash the unit again with a ratio of 2qts water to 1 qt acid for 5 minutes and see if the LOW salt light goes out.
He gave me his phone extension and asked me to call him if the IC40 does not work properly after a 2nd acid washing. Pentair will send me a new IC40 (my pool builder is bankrupt so I'm on my own here).
There is an Intellichlor Field Calibration procedure that you can find if you Google the subject. According to Pentair, this procedure will not work for any IC40 after V1.6.