Nissan Repair: AC turns off when I turn it to MAX setting 4., blower motor resistor, ac compressor

Question
My air conditioning will turn off when I turn it to full blast on setting 4. Settings 1 through 3 are perfectly fine but only when I turn it to the 4th setting the ac compressor clicks off and the light on the ac button goes off.

I already replaced all my relays/fuses/and blower motor resistor, with no luck. I'm starting to think I might have to replace the heater control unit?

Have you heard of this?
Any help will be greatly appreciated.

Thanks,

-Kris

Answer
Hi Kris -

Well, the only thing I can think of is a faulty switch. The fact that everything shuts off on the 4th setting, and only on the 4th setting tells me that there is an open circuit at that setting.

have you tried replacing that?

Other than that, I cannot think of anything else -

Hope this helps -
aloha
calvin