HVAC control testing

[Numbchux]

on my loyale, the HVAC control isn't working. the electrical part is working fine, so I have heat, but it comes out the middle. so the vacuum thing isn't working right.

 

at first I assumed it was that I didn't get the line hooked up right from the engine, but it appears that I did. Anyway, I've got another control here, that I assume works fine (it did when I took it out of my '85 and put it in the box in the garage anyway :-\ ). I'm going to swap them out tomorrow, but does anyone know which of the 4 vacuum lines on the back is supposed to get the vacuum from the engine? I assume one gets it from the engine, and the switch routes it accordingly to open or close the necessary valves. I'd like to make sure it really is the switch while I've got it apart.

[hooziewhatsit]

There should be 4 vacuum lines coming off the back on the controller. I believe the bottom one should have the engine vaccum on it.

 

IIRC, the vacuum from the vaccum canister, goes to the driver side of the engine bay, through the rubber grommet near the wiper motor, then across from there to the controller.

 

If you stick your head under the dash it'll probably be too loud to hear a vaccum leak there...

 

-Dave

[nvexplorer]

Having just replaced mine in my 93 Loyale I can tell you that it is the bottom one. After replacing my heater core my HVAC control unit decided to spring an internal vacuum leak. Pick n pull had plenty to choose from and everything works fine now. The top three vacuum lines have numbers on the rubber tubes in order from top to bottom as follows. 1, 2, 4 (there is no 3) and then the bottom one which doesn't have a number on the line. The HVAC unit also has numbers on the plastic right next to where you connect the lines so you can make sure that you don't put the wrong one on the wrong hole. When you have the lines off you can start the engine and figure out which one is sucking. You should be able to hear and feel it. If you can't then you might want to check the other end of it in the engine compartment. Good luck.

[Numbchux]

When you have the lines off you can start the engine and figure out which one is sucking. You should be able to hear and feel it. If you can't then you might want to check the other end of it in the engine compartment. Good luck.

 

That's exactly what I was thinking....I just wasn't sure which line was supposed to get it. thanks.

 

 

it's an EJ swapped car, so under the dash is a bit of a mess of wires, so if the vacuum leak is up there, it'll be a huge pain. but I know it's coming throught the firewall by the wiper motor....so I'll try it from the other end, and see where that gets me.

 

 

thanks guys