My truck has one remaining glitch, and I am not sure how to tackle it. My a/c system will function perfectlyfor weeks, then get a mind of it's own. It will turn off the a/c and pump regular air, and sometimes hot air regardless of the settings. I will hear the compressor cycling, and get hot air, sometimes the a/c button will light up sometimes it won't. My mechanic recommended I change out the dash controls, another one told me to replace my low pressure switch. I'm thinking about checking and cleaning my connections first.
Compressor, evaporator, and orifice tube are new.
I'm in deep South Texas, and am a/c is a necessity even in the Winter.
Thanks guys.

Low pressure switch is a common problem.

If the a/c light does not come on then I'd tend to agree with the Mechanic (sort of) there is something going on in the control unit.
I have a buddy that has issues with his control unit, just goes dark and stops working, we unplug it wait a few then put it back in and it works fine for awhile (it's worked great for about 6 months now) maybe it was a dirty connection or loose. (just thoughts) anyhow I'd start there. (with the control unit in the dash)

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Sorry, I forgot to mention i replaced the low pressure switch too. I was planning on doing the control unit connections today, so I figured since I'd have stuff removed, I'd see what else is worth checking into. Thanks.

The low pressure switch just does what it is called "low pressure". If the charge (refrigerant) leaks out to below the minimum line pressure it triggers the switch to simply not allow contact to the a/c clutch (if the refrigerant leaks out so will the oil, and possibly cause the compressor to seize). Since the 6.5 doesn't have vacuum like a gasser it uses electric motors to control the direction on airflow in the cab and the heater valve. So if those functions are intermittent then the control head is the culprit.

Last time it happened to me, I have to change the Compressor and everything needed changing when changing the compressor, Dryer, orifice, lp switch. Then it is good. The compressor is another weak point but what do you expect after 15 years.

I'll have to clean the connections today. Now the ac switch is on, the compressor is cycling, but the air coming out feels like I have it on "vent". Good thing the temperatures have been really mild recently, I sure don't look forward to the Spring with the truck acting up like this.
Thanks for the input guys.

There are leaks somewhere, sounds like what I had before I fixed it.