AC not working

[Oldtruck]

So I have a 96 ram 2500 with Cummins motor. If I am traving above 30 mph, the AC stops producing cold air. It should be noted that the tach, engine light, cruise control, water in fuel light blink erratically during this time. Fuel mileage and head lights do not appear to be affected.

I think it may be electrical, but really don't know where to start.

Any ideas?

 

[Shadow_Death]

How are your brakes? Do they feel like they're not working as strong as they used to? I'm asking because giving that this motor doesn't produce vacuum it should have a vacuum pump. My 96 1500 uses vacuum for the ac andcruise control to work. I can't say much for the tach as I don't have one.

Just throwing some ideas out there until someone else comes along. My niece's 97 f250 had all sorts of issues when her vacuum pump went out.

 

[dudeman2009]

Engine vacuum has nothing to do with the A/C operation. The brakes are hydraulic assist from the power steering pump, the vacuum pump only controls the 4x4, cruise and vents.

If the dash is erratic above 30mph thats where you need to start. first check for codes with a scantool and see if it points you to anything.