What is it?

[Rallycat66]

1995 Impreza L AWD 1.8L engine 5MT.

There is a thing-a-ma-gigger bolted to the top left side of the intake manifold. It sits right next to the air intake pipe. Lines going into it from the air intake just after the MAF and another from the intake manifold just after the throttle body. There is a spring loaded dial on the top with both lines going into the right side just below the dial. It's plugged into the wiring harness underneath.

Wondering what the heck it is and whether the fact that the line from the air intake is broken off is going to be a problem.

Tim

[Rallycat66]

Don't make me post this on NASIOC to find out!!! :machinegunleft:




Dealer says its an air valve/meter for the A/C system. I tried running the car with this disconnected and it will not idle. Talked to one of the techs and they said that I could probably bypass the valve to close off the vacuum system again (A/C doesn't work anyway) and leave the now disconnected valve plugged into the wiring system. Anyone have any thoughts as to what effect this would have on the car?

Part #73711 on the parts diagram from the dealer if that makes a difference to you. Don't really feel like coughing up $80 for this piece if it's not needed except for the A/C to work.

I'm personally confused because it's connected into the intake system (one vacuum line comes from the air intake just past the MAF, the other line goes to the intake manifold just after the throttle body (connection threads into the intake just above the PCV valve). What would the A/C system be doing taking readings off that and why would it cause the car to not idle when it's disconnected from the wiring harness?

Tim (clueless about A/C systems)...

[409industries]

I don't know what that is that you're describing (not that your description is bad or anything) Does anyone know what this piece is?

[rollo]

It doesn't sound much like an A/C component, although I'm hardly an expert in that area (actually I'm not an expert in any area :D ). With vac lines in those positions, it almost sounds like an overboost valve or something like that.. except of course with the engine not being forced induction that doesn't make any sense. So maybe it's a component which senses level of vacuum and adjusts... something.. based on that..? Possibly it compensates for the drag that the a/c compressor causes by adjusting the idle speed? (secondary butterfly valve on the other side of the "spring-loaded dial"?) The plug tells it whether the a/c is on or off, the lines measure the vacuum and the dial opens or closes the valve as appropriate?

I suppose you could check by hooking it up and switching the a/c on and off and seeing what happens. Even if it doesn't run cold, the electrical components are probably okay - although it probably wouldn't activate if the pressure switch(es) are knackered.

How many prongs on the plug?

Random guesswork ftw! Pics of this thing would be handy.

This thread may help a lot:
http://www.dirtyimpreza.com/forums/showthread.php?t=1373

[Rallycat66]

Here's the part that I'm referring to...

http://webpages.charter.net/carsoft/Impreza_Thing.jpg


Note the top connection is broken.

The A/C system in the car is completely DOA. Nothing at all happens when the switch is turned to AC or Max AC. The compressor doesn't even start turning. Haven't bothered to try to figure out why. I thought this might be a vacuum switch that would detect when you were on the throttle hard and would shut off the A/C (more recent Imprezas have this feature), but that is pure speculation.

So anyone have a definitive answer on what this is, what it does, and whether I can just bypass it and connect the two hoses together (or should I just plug the two hoses?)?

Thanks...

Tim

[rollo]

Oh. Well that's not what I was thinking at all :D

If the a/c compressor doesn't kick in when you hit the button, probably the refrigerant is too low and the pressure switch isn't activating (working from memory here). You should be able to bypass the pressure switch and get it to kick in, but since you don't care apart from this thingy, it's really a moot point.

Okay so by the size of it, it's either open or closed normally, presumably. I'm guessing it's an adjustable idle stabilisation valve, with the dial thing being the 'adjustable' part.

I'd put a multimeter over the terminals it plugs into and see what it's reading (continuity, volts, resistance), then check if its default state is open or closed. If it's usually open, connect the hoses, if it's usually closed then plug them. Then either leave the valve connected, or dummy it (short it, or put a resistor in if it's looking for a specific resistance.. that kinda seems like a lot of hassle, I think I'd just leave it).

Obviously I do not have a definitive answer (sorry). A shop manual would though... let us know what it turns out to be.

[RoadRunner]

Cold start valve / air assist valve. When the A/C compressor turns on it allows air in to the IM and bypasses the TB, or something like that...

[RS-ti_Andy]

what he said ^^^^^^^^^^ you could just bypass it but then you might have problems at idle or starting.. first i would reconect the hose that is broken, second i would try to bypass it.. other wise u need a new one.. but go junk yard shopping first!

[rollo]

Huh? a) the flange on the valve is broken, not the hose b) given that the a/c opens the valve, and the a/c is broken, then the easiest thing is to plug the hoses - or better, cap the nipples at the other ends of the hoses - and leave the valve in there.

[RS-ti_Andy]

ohh.. yeah but he said its not idleing like this..wait..so confused

[Rallycat66]

ohh.. yeah but he said its not idleing like this..wait..so confused

Wouldn't idle if the valve is disconnected from the wiring harness (i.e. I can't simply remove the whole thing from the car and call it a day). Car "seemed" to run OK when it's plugged in but with the broken stem. It's a slug with the 1.8L, but seemed to be smooth and running correctly.

I plugged the lines, but left the valve in the car and plugged in. I'll keep an eye out for this part in a junk yard. I have not road tested it yet (discovered both inner front CV Boots self destructed recently. New inner and outer boots sitting in the trunk and will be replaced when the new clutch comes in) but it seems to be running smoothly in the garage.

Tim

[dome24]

mine has been broken for a long time before and after the ej22 swap, its always ran fine til lately, i never really thought my issues were related
i taped over the busted nipple on the intake tube and just left the valve thingy hooked up to the motor and just busted off the top niple
but my ac has always made a loud hissing and it runs really rough at idle with ac on, its great i can turn my ac on and off and it hisses like its boosted i always thought it was just the compressor failing:eek:

[dome24]

any update on what exactly this thing does, i removed the valve completly today, taped the intake side and plugged the manifold side. Its been broken for over a year Its below zero right now so i hope it starts in the AM

[Rallycat66]

Finally droke down and got the "real" Subaru shop manuals for the 1995 Impreza.

This thing is a Fast Idle Control Device (FICD) and is only found on the 1.8L models. It basically helps control the idle under heavy electrical load (A/C, heater, etc). If you find that your car doesn't like to idle when you turn things on in the electrical or A/C system. This bugger probably should be replaced if it's broken (which most seem to be - it's real easy to snap that upper connection when you change an air filter).

Tim

[dome24]

so can i leave mine just plugged off at the motor? i upgraded to the ej22 from the 18