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Old Aug 2, 2009 | 07:59 PM
  #1  
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4bigred
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AC issue

The other day while I wiped the dust off the dash I moved the switch to 4X4 low. When I started the truck the air was on and running, but no air was blowing out of the vents because the baffles wouldn't open. I read somewhere on this forum that this is caused by a vacuum leak. My question is; where do I start to look for the leak and is it something a relative novice can fix?
 
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Old Aug 2, 2009 | 09:28 PM
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I was under the impression that only occurred on diesels, but even if you have a gas motor, I would start at the hubs. Inspect the hoses that run from the fender liner to the steering knuckle, make sure the line is on, and not cracked/split.

My old trick for engine vacuum leaks is to spray starting fluid around the hoses while the engine is running. If a hose is leaking, it will suck up the fluid and the motor will rev up. Vac leaks are pretty easy to cure, a new length of hose to replace the damaged one is pretty easy mechanicing.
 
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Old Aug 3, 2009 | 06:50 AM
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I do have a 6.0 PSD so I'll start going at the lines to the hubs. Thanks
 
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Old Aug 3, 2009 | 10:11 AM
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If you don't have a vacuum pump/gauge,try this way;

Start truck, turn on a/c and esof.
(air is defaulted to defrost right?)

plug vacuum line at right hub (line ,not the hub)
If a/c switches properly, problem is in right hub,(leak) if not re-connect and go to left hub and repeat.

If neither hub leaks,(a/c stays on defrost) disconnect line at vph solenoid and plug solenoid port.(not vacuum line)

If problem corrects,you have bad vacuum line/s (replace both)

Give a min. for a/c to switch after discinnecting lines during check.
 
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