Is there a wY to convert these trucks to electric vacuum? When you set in traffic, it's like the ac ducts all close up. I was told this is normal, or are there other problems. Thought about getting a chip with the idle up, for when setting still of course. Will those make the ac kick a little better?

 

Sounds like the vacuume pump is getting weak, or you have a leak some where. The vacuume pump should pull a minimum of 19 in. On my trucks with good pumps, the vents never defaut to the defrost position.

 

That's not "normal". +1 weak vacuum pump. Are you holding your foot on the brake the whole time? That might have an impact. An electric pump would not be sufficient to boost the brakes. You could convert the brakes to hydroboost and then put the HVAC vacuum on electric.

 

Might be vacuum pump. I have spayed some wd through the vacuum side. It works for a while. Maybe there's a check valve gummed up?

 

It could be the vacuum line going to the selector valve that is starting to dryrot. Pretty common issues on these trucks. It'll be on the passenger side. Something tells me off the top of my head that the line might be blue or white. I can't recall right now.

I know mine went south and I had to replace it back up into the "harness" that it runs into. I could break it by hand it was so hard.

 

My vac line over on the passenger side by the hood hinge tends to go bad, its white. Cut out the bad section and replace with rubber line over it. High idle helps a lot and you also might have a freeze up problem. Try putting it on vent for awhile to see if it frees up.

 

this tells me your vacuum pump is on it's last legs.