Marine Air heat on 330 express

My problem is related on my 2005 33 Express. My control panel has a heat setting but I can’t seem to access it. The on/off button does nothing more than that. The control panel shows ac, fan and heat. Can someone please advise how to change it from AC to heat?
You need to get into “p 1” and then set to 0 (zero).
Seems a little tricky but just be patient and it should go quick

Start with section 7.3.1 then 7.3.2, etc

Skip 7.3.3 (read that section)

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It works ok on heat, you're not going to get blasting heat but it will slowly raise the temp in the cabin. I have a small electric heater that works fine for the few times I need it as the cabins really are not large areas.