I've got a Sears Die Hard AGM battery in the car and have a CTEK 3300 hooked up to it. Does anyone know the correct mode for the CTEK, the car mode or the snowflake?

 

I don't have a 3300, mine's an MXS 5.0 (doesn't have a manual snowflake mode), but the manual shows the charge rates for car and AGM are the same except for the bulk and absorption phases, so if the 3300 boosts the voltage for those phases in snowflake (check your manual!) that's the one to go for. For the float and pulse (top-up) phases there's no difference between the modes so if you're just maintaining it either mode should do.

I'll now wait to be shot down in flames!

 

Per the instructions for the CTEK MUS4.3, the snowflake (winter mode) should be used to maintain an AGM battery.

My XJ has an AGM battery.

 

I use the car icon if there's a chance I will drive the car which I have been.

 

Here is a link to the CTEK video;

 

Do you have an AGM battery?

 

No.

 

Your setting is correct - "car" icon for a conventional battery. The OP asked about the setting for an AGM battery; that's why I wasn't sure.