Coffee Can, why do some have two "nipples"

[Toploader]

Ok I get that,but the blower motor stops and starts depending on the position of the gas pedal....what does that have to do with the blend door? The temp slider was all the way to the left at 60 degrees....and motor switch speed was on high.

With ATC systems, the blend door position dictates the fan speed by some means. I never dug deep enough into the system to find out how it does it though.

[kishy]

If you lose vacuum (as happens when your check valve and reservoir aren't effective, via vacuum leaks), the blend door servo returns to full hot. Push pedal = open throttle = lower vacuum.

It has an integral switch that changes the blower speed so the ATC system only blows the fan in situations where it will help you achieve your intended temperature, instead of blowing air that is the wrong temperature to achieve the setting you have set it to.

[sly]

pedal down... no vacuum blend door goes to hot... fan goes to low speed since it's set to cool. This is almost always the check valve on the vacuum tree being dead (or the vacuum reservoir (soup can) having a hole in it) as the system needs vacuum to maintain cool air. Long runs up a hill will also cause this if the system bleeds down during that high engine load.

[Toploader]

Ok....now I am getting educated......I replaced the check valve last year, no change.....but I never changed the coffee can.....so now that I was able to find a very close match for my '86 with a 1980 Crown Vic or MGM coffee can I will put that on and see what happens, I also never replaced the vac line that goes inside the car, only changing the one from the vac tree to the coffee can.

pedal down... no vacuum blend door goes to hot... fan goes to low speed since it's set to cool. This is almost always the check valve on the vacuum tree being dead (or the vacuum reservoir (soup can) having a hole in it) as the system needs vacuum to maintain cool air. Long runs up a hill will also cause this if the system bleeds down during that high engine load.

[gadget73]

There is a secondary fan switch mounted to the top of the blend door, and a link rod runs between that switch and the blend door. Middle door position = low fan speed, end door positions = high speed, in between that is medium speed. Thats what the "auto" mode does, it lets that fan switch run the show. If you don't run it in auto, that second switch does nothing. The blend door is moved by a vacuum motor that is controlled by the interior air temperature sensor. The temperature slider on the dash controls that. There is also a valve up there that switches from fresh air to recirc air. At either end of the blend door travel, it runs in recirc mode. Thats why it sounds like it gets louder or softer sometimes from under the dash.

Usually whats actually happening when it seems like the air stops is that it is moving to come out another place. Next time this happens, stick your hand over the defrost vents. Fair bet you'll feel air starting to come out there. The default position for ATC when it loses vacuum is hot defrost. Anything besides that requires vacuum.

[Toploader]

This is better than going to college That vac valve that attaches to the dash...one hose goes to the can, the other goes into the car....where does that hose terminate?

There is a secondary fan switch mounted to the top of the blend door, and a link rod runs between that switch and the blend door. Middle door position = low fan speed, end door positions = high speed, in between that is medium speed. Thats what the "auto" mode does, it lets that fan switch run the show. If you don't run it in auto, that second switch does nothing. The blend door is moved by a vacuum motor that is controlled by the interior air temperature sensor. The temperature slider on the dash controls that. There is also a valve up there that switches from fresh air to recirc air. At either end of the blend door travel, it runs in recirc mode. Thats why it sounds like it gets louder or softer sometimes from under the dash.

Usually whats actually happening when it seems like the air stops is that it is moving to come out another place. Next time this happens, stick your hand over the defrost vents. Fair bet you'll feel air starting to come out there. The default position for ATC when it loses vacuum is hot defrost. Anything besides that requires vacuum.

[gadget73]

The hose into the car goes to a tee. One side goes out to the TBL, the other side goes to the climate control head. Its pretty much a straight shot from the climate head to the firewall, or it would be if you had arms like Olive Oyl anyway. I've done it once, and I left a lot of blood inside the dashboard for my troubles.

[Toploader]

Ok......since I completely disconnected the TBLS and tossed it, and then just dum-dummed" up the end I should have less hassle running a new hose. But that will be the last thing, first will be putting in the NOS coffee can, then if still the same, put in a new vac valve. Oh btw, I noticed that the nipples coming out of the valve are not the same length, does it make a difference when I run the hose to the coffee can and the other to the control head?

The hose into the car goes to a tee. One side goes out to the TBL, the other side goes to the climate control head. Its pretty much a straight shot from the climate head to the firewall, or it would be if you had arms like Olive Oyl anyway. I've done it once, and I left a lot of blood inside the dashboard for my troubles.

[gadget73]

no difference, they both connect to the same point