The vacuum reservoir should be on the drivers side inner fender, beneath the junction block.

 

Well, I replaced every vacuum component between the throttle body, and the climate control head, and the noise still continues.


However, I extended the vacuum and wiring harness for the control head, so I can have it sitting on front seat, while plugged in and running. Now I''ve found that the noise is actually coming from somewhere behind, where the climate control head should normally sit.


I know from taking apart similar car in the wrecking yard that the vacuum harness goes into a junction block about 12" behind the climate control head. From there the black line goes to check valve on firewall in engine compartment, and the other lines to to actuators inside dash. I''m starting to suspect that the noise is coming from this junction block.


Does anyone know if the colored lines leading from the climate control head (to actuators)should have vacuum under the below conditions.


1. Car fully warmed up and running.


2. Climate control head plugged in (electrical and vacuum), but turned off.


Under the above conditions I''m still getting the whistling noise coming from area inside dash behind climate control. It seems to me that with the climate control plugged in, but turned off, no vacuumshould be getting down to the actuator lines? Does anyone know if this is correct?

 

check the vacuum assisted automatic e-brake release thingy. not sure if yours has the same kind as my 88 (my wife''s 93 has a similar setup). if you take the kick panels off and look at the base of the steering shaft at the firewall, there''s a third circle looking valve that has once line coming in from the firewall to a check valve and then one line out to the vacuum actuator on the e-brake. on mine, the actuator itself was leaking air and making the nice hissing noise. took the line from the firewall and capped it since I couldn''t find that part and the leak stopped. no more hissing noise. in yours, it may be the valve itself, which is still available from autozone in the case of my car. Try that, unplug the vacuum from the valve on the steering shaft (connected to the gear shift) and plug it and see if that stops the noise. that never affected anything in my car except the ability of the vents to stay put (blowing out the vents instead of the floor, etc, etc)

 

I actually plugged mine off at the vacuum block on firewall, inside engine compartment. That was one of my first thoughts also.


Well after the holiday I get in there once again.

 

Well to make a long story short, I dissembled the center portion of my dash, until I came across the vacuum actuator that was making the whistling noise. This particular acutator has two vacuum lines going to it, red and yellow, and appears to be responsible for defroster and floor vents.


I was able to remove it from its location, extend vacuum lines to it while it was outside of dash, the noise was coming from the red port on actuator. For the time being, I have replaced it with another unit from the wrecking yard.


My question now is, does anyone know if both the red and yellow lines are supposed to get vaccum at the same time. I''m wondering if has the ability to test the vacuum on these two lines within a similar car?

 

[img]uploads/Freedom/Actuatorsb.jpg[/img]

 

Just thought I would let everyone know that six months later, after replacing the failed actuator, the noise has not returned. I have included a picture of the part I replaced.

 

glad that sorted it. I managed to find a replacement brake release motor (vacuum assist) for my MGM. place about 150 miles away had ONE in stock and was able to ship it to me. Hopefully that will last another 20 years.

 

Update on mine. The part failed and started hissing again. I guess a little over a year is all I could get from a 20 year old replacement part.