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Brian W
Brian W, Master Chrysler Tech.
Category: Dodge
Satisfied Customers: 585
Experience:  Chrysler Gold Certified, Ase Certified
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1996 Ram 1500: liter..defroster when I accelerate..vacuum leak

Resolved Question:

My 1996 Ram 1500 5.2 liter has an apparent vacuum problem. My A/C ducts switch to the defroster when I accelerate. I can't find a vacuum leak and have already installed a check valve in the vacuum line to the A/C. I even ran a new vacuum line directly off the intake to the A/C system to no avail. I replaced the controls switch in the dash and checked all the air motors on the A/C and found no vacuum leaks. What else can I do?
Submitted: 10 years ago.
Category: Dodge
Expert:  Chrysler man replied 10 years ago.

There iisn't much question that you are losing vacuum somewhere. The problem is finding where.


The way to track it down is to use a vacuum gauge and tee it in at various points to isolate where the problem is so you can see what areas are dropping. If you have a leak in the system anywhere such as one of the vacuum actuators, vacuum lines or switches.

Customer: replied 10 years ago.
Reply to Chrysler man's Post: I have put 15 inches of vacuum on each of the actuators and they have held fine with no leak down. Is this acurate with the truck not running?
Expert:  Brian W replied 10 years ago.

The 5.2 engine is notorious for having a internal engine vacuum leak. There is a bed plate and gasket located at the bottom of the intake manifold. This often goes overlooked because it is not accessible. Sometimes a slight pinging noise on acceleration can be noticed when this gasket is torn. The intake will need to come off and the gasket replaced.



This is what the gasket looks like.



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I hope this helps if so an accept is apprerciated.

Brian W, Master Chrysler Tech.
Category: Dodge
Satisfied Customers: 585
Experience: Chrysler Gold Certified, Ase Certified
Brian W and 6 other Dodge Specialists are ready to help you
Expert:  Chrysler man replied 10 years ago.

At this stage you haven't confimed any vacuum leaks at any locations or that there is any type of vacuum leak in the engine so don't be jumping to any conclusions on the engine until you have measured engine vacuum at a direct port..


All you have tested so far are the actuators. that wasn't likely anyway.


You need to uses a vacuum gauge and start at the engine and see what you ahve for vacuum. If you have over 16" of vacuum at idle, then you need to move inside on the vacuum supply line and see if you still have the same vacuum as the engine showed.

Expert:  Brian W replied 10 years ago.

Ricky, I think we are on the right track here. If there was an obvious vacuum leak I'm sure you would have found it by now.


HammerT's QUOTE:


There iisn't much question that you are losing vacuum somewhere. The problem is finding where.

Expert:  Chrysler man replied 10 years ago.

I'm referring the the vacuum network under the dash or vacuum reservoirs.


You need to systematically find out where this is happening. So far nothing has pointed to the engine being the problem.