What is this

[Pomorza]

Hey guys

Don't want to thread jack so I'm going to ask this in another one. What is the little thing that sits in front of the EGR valve.(picture included)

Jan

[ozconnection]

That thing looks like the idle speed 'increaser' for when the A/C is turned on.

[sblake01]

That is the 'fast idle actuator'. It draws vacuum from the F.I.C.D. magnet valve which appears to be missing on your car. Has your AC, or at least parts of the system, been removed? (Thanks to JeffG78 for the pic)

Edited February 4, 2011 by sblake01

[Pomorza]

When I bought the car the AC didn't work so I chose to remove it. That part or parts (hose and all) were not on the car when I bought it. I believe the previous owner removed it when it broke and didn't bother to replace it. Without the rest of that system is that part pretty much useless? Does it affect the cars vac at all?

Jan

[sblake01]

You'd have problems with you heater since the other magnet valve controls the mode doors which direct the airflow in the various heat/defrost positions.

[FastWoman]

^^ What Steve said.

Jan, it's interesting that your HVAC vaccum control port is also plugged. It's the plug in the intake manifold maybe an inch from the vacuum line to your brake booster. I forget on the '76 (I used to have a '75) whether the air handler is controlled by vacuum. Do you have hot air from your heater?

[Pomorza]

^^ What Steve said.

Jan, it's interesting that your HVAC vaccum control port is also plugged. It's the plug in the intake manifold maybe an inch from the vacuum line to your brake booster. I forget on the '76 (I used to have a '75) whether the air handler is controlled by vacuum. Do you have hot air from your heater?

I do have hot air from the heater on my feet and on the windshield yes, as I used it this morning as it was 20. The cable that controls the blower box flap (the thing on the bottom side of the blower motor housing that directs air, don't know what that is called), is connected to something but I don't know what. Since its winter I made it so that air gets drawn from the inside.

What does the HVAC vacuum control port do?

Jan

[cozye]

his heater control vacuum source is probably plugged directly into the manifold, or the vacuum canister is directly connected to it. That's what I have had to do since magnet valves are broken and NLA.

[FastWoman]

Jan, by "HVAC vacuum control port" I mean the fitting that would be in your intake manifold if you didn't have the hole plugged. On my '78, there's a vacuum line that controls the air handler inside the dash. It runs to the mode switch (AC, vent, heat, bi-level, def, whatever) and opens and closes doors, stopcocks, etc. as needed. The mode switch is simply a complicated air valve that diverts vacuum where it's needed. Your air handler might be controlled differently. I don't know. If you can move the mode lever while the engine is off and hear/feel doors and parts moving around, then perhaps it's controlled somehow by wire, and not by vacuum.

[TomoHawk]

The vacuum canister located underneath the vacuum solenoids (if it's still there) is supposed to hold some vacuum for when the engine can't draw enough. That should make it so you could probably get the air doors to move a little with the engine off.

FWIW- My vacuum solenoid valves were removed when I got the car (the a/c wasn't working, but the evaporator was still installed) so the vacuum line goes straight from the intake to the mode switch, and everything works fine, but there's a slight hiss from a brittle hose.

[grantf]

his heater control vacuum source is probably plugged directly into the manifold, or the vacuum canister is directly connected to it. That's what I have had to do since magnet valves are broken and NLA.

I started a thread on this subject. Find post AC elimination...

I was thinking of bypassing the magnet valves just like you have mentioned. Does all of you're heat controls operate normally now?

[sblake01]

Seemd to me that that would work though I never tried it. The vacuum source for the mode doors really doesn't need to be 'switched' like the one for the FICD, since the vacuum selector would 'tell' the vacuum what to do. I always thought the vacuum bottle was redundant siince you really only need the mode doors to operate when the engine is running.