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Front AC dies when vacuum low

7K views 11 replies 4 participants last post by  Bert 
#1 ·
I have a 2003 Navigator that has an annoying AC poblem.
Whenever I accellerate (even slightly) all the air stops blowing through the front air ducts. When I am coasting o cruising at light load, the air blows just fine. Since these conditions correspond to low vacuum conditions, I assume that there is a problem with the vacuum accumulato or something similar. The poblem is that I cannot find any of the related vacuum components. I have the helm factory manual on disk. It shows pictues of all the componenets, but I cannot find anything that shows me where these components are located. I have other ford factory manuals and they have really good sections that diagram the location of components. Why doesn't this one?
 
#2 ·
The manuals don't show the location of the reservoir or the check valve. The only way to find them is to follow the vacuum lines from the engine to the firewall. The check valve can be bad too. It's supposed to hold vacuum in the circuit.
 
#3 ·
I have found the poblem, sort of.
I found some sort of vacuum switch on the fiwall next to the battery. It has a two pin electrical connector and two vacuum ports. On of the vacuum ports is plumbed into the vacuum line that goes to the vacuum reservoir (behind the battery). The vacuum switch leaks vacuum at all times. Even when the other port is plugged.
Does anyone know what this switch is?
It has a number on it "E8AE-9H465-BA
 
#7 ·
Yeah I would guess a vacuum line got unplugged accidently or something. Mine was doing that and it was the little vacuum line on the hot water valve there under the hood. I think it got unplugged when I was changing the sparkplugs or something. Have you had any work done on the truck lately? Like a tune up or something?


- Mike



Hot water supply valve .....
 
#9 ·
Yeah I would guess a vacuum line got unplugged accidently or something. Mine was doing that and it was the little vacuum line on the hot water valve there under the hood. I think it got unplugged when I was changing the sparkplugs or something. Have you had any work done on the truck lately? Like a tune up or something?

- Mike
Mike,
It turned out that my problem was the little vacuum switch that activates the diaphragms that connect the front axles in 4WD. It is on the firewall right behind he battery. I will post a pic later.
This vacuum switch just leaks continuously. I bought a new one at the ford dealer this morning. It cost about $50 and the new one does not leak.
 
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