Help..

I'm trying to locate the heater pipe air relief cap on my 93 mercury villager.
I have found the radiator air relief plug and the engine air relief plug, just cant seem to find the relief cap for the heater pipe.

On my 96, it's right behind and below the throttle body, which is the part that has the gas pedal cable pulleys attached to it. Two heater hoses come out, and a smaller 5/16" pipe comes out with a rubber plug over the top, with a pipe clamp around it. It is just about impossible to see. It is behind one of the heater hoses. But it is there, and you may just be able to see some of the shiny pipe clamp. Use a good flashlight and feel around. Get in there with a mini socket wrench to remove the pipe clamp, I think it's 7mm, and then use a long screwdriver to jam the nipple rubber plug off, aiming downards and slightly towards the back of the car, from to the left, slightly behind the throttle body.