[quote]Originally posted by Greg86andahalf:
<strong>I also have a leak in those lines. They go into the wheelwell area. I need to research the archives and the manual on what those lines feed.</strong><hr></blockquote>

The vacuum reservoir and cruise control unit are there in the wheelwell.

 

Thanks Mike.

I think alot of my minor problems will begin to clear up as I ring out the vacuum leaks.

 

Hey Nicole,

just wond'rn how the vacuum issues are coming along. Any update yet?

 

I'm soo busy this week, and we temporarily have so much stuff piled up in the garage that I can't even get to the beast. I plan to spend some time troublehooting on the weekend. I'll keep you updated!

Thanks for asking!

 

OK, This is getting complicated... The "air sucking" noise - which I beleive came from within the center console - is gone, but the AC is very weak.

Here is what I checked and found:

- AC Compressor seems to engage - I can hear the clutch, and the air temperature drops somewhat

- No bubbles in the little "viewing glass" on the AC line

- Heater valve (one year old) moves, with slight delay

- Fuel line cooling area stays warm

- Black/blue valve at the brake booster: Holds vacuum in one direction, not in the other. It is mounted with the black part towards the brake booster, and the blue part towards the 4-way connector.

- When I pulled the vacuum line that comes from the INTAKE manifold and goes to the 4-way connector near the brake booster, there was still vaccuum there after the car sat for a week!

- The line from the 4-way connector to the AC vacuum manifold in the center console: It was a little loose at the AC vacuum manifold, but was not leaking.

- No apparent vacuum leakage within the AC system - I plugged the MityVac into the main "intake" of the vacuum manifuld, and then checked vacuum with all positions of the lever.

So, the question is: what was the "air sucking" noise, and why is it gone suddenly? Could it have been a Freon leak? Then, why don't I see bubbles...

I am totally lost now! <img src="confused.gif" border="0">

 

Hi Nicole,

I doubt the the sucking sound was a freon leak because if enough leaked out, the low pressure cut-off switch would keep your A/C compressor from coming on and you say it does come on.

Greg

 

Nicole/Greg/Mike,
Have you checked the vac. splitter located behind the right front wheel well? It's easy to get to.
Turn right front wheel for easier access, remove screws/bolts from aft splash guard I think they were smaller than 10mm, maybe 8mmm.
You should see a bunch of electrical runs and some Vac. lines bunched together. There is a plastic splitter - I think a 45^ - check for leaks and a break in the splitter. Clean things up a bit and zip tie things up the way you want.
Keep in mind things bounce around in there, zip tie accordingly.
I bought my replacement splitter at Home Depot for $1.37, plumbing or lawn sprinkler section.
HTH John S. & Pattycakes

 

John:

I checked the vacuum line that goes into the wheel well, and it holds vacuum. I don't believe that's where the problem is in my case. In fact, I really was not able to find any vacuum leak in and around the AC, and brake booster. I do know that there is a slight loss in the vacuum line to the transmision, but that appears to be a separate vacuum circuit, and is not (yet) significant enough to even affect the transmission.

Bottom line: There is vacuum in the HVAC system. That's why I did not see a point in digging deeper and pulling off the colored lines and test them separately. Am I wrong?

 

Depends upon how you are testing the vacuum.

If you hook up your MityVac to the supply tube, pump away, and get vacuum - no, not adequate testing.

If you hook up to the vacuum line, pump up a good vacuum, the turn the ignition on and test every position on the HVAC controls, then you will know that the system is tight. After you move the lever, it is normal for the vacuum to fall, as the solenoid valve opens to a different actuator - the test is whether you can pump the vacuum back up and have it hold for a reasonable period of time.

If you have no leaks in the HVAC system, perhaps you should consider donating your car to a museum somewhere, because that is VERY rare! ;-)

 

Nicole,

I wonder if your overall vacuum supply to the HVAC is low. On mine, I gauged the vacuum at the booster. Good level. I gauged it at the HVAC manifold, low level. In my case, the black/blue check valve was restricting or lowering vacuum. (tested by pulling vacuum thrugh the valve to a vacuum gauge. Big drop. I did the cleaning method for the valve and vacuum does not drop through it any more and it still works as a one-way check valve.

I know you replaced your valve, but can you check the vacuum level at the supply line which feeds the manifold? Let's make sure sufficient engine vacuum supply is present at the HVAC.

John,

I see a splitter in the engine compartment that feeds lines into the wheel well. I removed the wheel well cover the other day and found that both lines did hold vacuum. I see no additional splitter in the well itself. The 2 lines go to cruise and vacuum reservoir.

My original belief that the line to the wheel well was leaking was wrong. The reservoir requires a few pumps to get a reading on the gauge because of it's size. I was pumping once and not getting a reading, but with a number of pumps to "charge" the reservoir, it held fine.


Wally,

Thank you much. I simply attached the mityvac to the supply line of the HVAC manifold and it held vacuum. I did not move the selector. (good thing it is still apart, easy to re-check).

Thanks,
Greg

 

Could be a sticky expansion valve. It may have been a hissing sound you were hearing and not a sucking sound.

The only way to test this would be to take the car in to a A/C repair shop and have them hook-up their gauges to the system and check high and low pressures during operation.

In the end, you will still here a sucking sound. But the next one will be from your pocket book as the dollars get sucked out.

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Max

 

Ok, I completed the window project, now I'm back thinking about the AC. I tested as Wally describes, and found no vacuum leaks (no, Wally, I'm not going to donate!). The fuel line cooling stays warm even with AC turned on. The engine idle still changes slightly when I turn on the AC. I don't know how to verify if the AC compressor clutch engages. The air temperature seems to drop minimally with the AC on, but it's by no means getting cold.

So here are a couple new questions:

In the little glass thingie next to the radiator, what color should I see - does Freon even have a color? It looks kind of greyish, no bubbles.

Since what I called an "air sucking" noise in the center console was there for only one day, I am wondering if it was actually freon leaking somewhere in there. If that's the case, and the freon has escaped, then this would explain why the noise is gone, right?

So, what is in the center console that the freon could leak out of, and where would that be located? Am I in for a console removal?

 

Nicole wrote:

[quote] I don't know how to verify if the AC compressor clutch engages. The air temperature seems to drop minimally with the AC on, but it's by no means getting cold.

So here are a couple new questions:

In the little glass thingie next to the radiator, what color should I see - does Freon even have a color? It looks kind of greyish, no bubbles.
<hr></blockquote>

Verify that the clutch is engaging:

With the engine running, you can look at the front of the AC compressor. From the front, it's the lower left side pulley, below and to the right of the air pump drive pulley. I guess that makes it the lower drive on the passenger side, closest to the engine oil sump. The front pulley is a two-section arrangement. With the clutch disengaged (no AC) the pulley (where the belt rides) spins around the stationary center section. When the clutch is engaged, the center section spins with the belt and pulley. Watch your fingers around those fans.

Freon flowing through the sight glass:

Freon is an almost colorless liquid, and has a small amount of oil circulating in the liquid. When the compressor isn't compressing, the freon flashes to gas and is invisible anyway.

With the system running, you can see that there are a few bubbles drifting by the glass in a flow of -almost- water-clear liquid, and see streaming little trails of oil in the liquid. As the freon chrage reduces and/or the air temp rises, you may see more bubbles in there as the condenser converts a little less gas back to liquid.

'Greyish with no bubbles' usually means the compressor isn't circulating the freon past the glass.

If the compressor isn't rnning at all when you push the button:

You may be low on freon. There's a safety switch on that little tubing manifold on the drier (that's the can with the sight glass in it). On your S4, the switch is the lower of the two sensors, and has a plastic two-wire connector plugged in to it. The top sensor, the one with the two little nuts holding the wire ring connectors on, is a presuretransducer that operates the fans and the flaps in the grill (if you have them).

You may have a blown fuse, a failed panel relay, failed evaporator 'freeze' switch.

Your compressor relay in the dash controller may have failed. There's fixit writeup on the Greg Nichols website, and some comments from users with hints on a replacement relay. There's also an electrical diagnostic procedure that will help you isolate the problem.

HTH!

 

Thanks, Dr. Bob!

I will take another close look at all this.

You might be right with the low freon - the noise I heard in the center console was probably not "air sucking", but "freon escaping" from the area of the evaporator udner the dash.

I might have to take it to the AC shop that Rick K recommended (near DEVEK), for some leak sniffing. I just hope it's not the evaporator itself that leaks.

I'll post an update here!

 

LP SWITCH TEST...jumper the LP switch momentarily. This will by pass the LP shut off on the compressor. You only have to do it long enough to hear the clutch engage or see the compressor turn. This will tell you that the system is low on freon since the system works with the switch jumperd but doesnt other wise (may be a bad LP switch but i doubt it).

FREEZE SWITCH TEST...with the AC off and the LP jumper still intact( i say that so you are 100% certain the clutch will now engage),go under the rainsheild and find the freeze switch. On the blower tunnel...2 purple/yellow wires that lead to a device mounted on the blower tunnel. Pull them off and jumper them. THIS BY PASSES THE FREEZE PROTECTION. With it jumpered the compressor should also run when the AC button is pressed.

Up to this point you have tested the protection switches by bypassing them (its very easy to do) you can use the same jumper lead you SHOULD have in your glove box for the fuel pump relay when it fails shortly : )

If non of these things work you should check the clutch itself.... find the power lead to it (a SINGLE red wire) that comes off the top of the compressor and runs up to the wirng harness (next to the pax side Distributor) With a 12 V source (low amps..i used 2.5 on my batt charger) connect the neg lead of the batt charger to the belt ajustment bolt on the compressor (this is a ground for the test). Now take the red lead from the charger and touch the clutch power wire. YOU SHOULD HEAR A SOLID "CLICK" and be able to see the clutch face move in.

if that works you have now eliminated a clutch...and also with the other tests, low freon...and a bad freeze switch.

If the clutch doesnt click with a direct 12v source you may have a bad clutch coil. This can be checked with an ohm meter...appz 3.2ohms is good from what i hear.

If the clutch does indeed work with the direct 12v, now you can go into the HVAC head in the center console and mess around with the "little blue relay that DR Bob and others have mentioned. oh joy!!

HTH...the trouble shoots go from easiest to hardest. I just did this whole deal on my car. It was the blue relay in the HVAC that was bad. I took it all apart..put it back together having NO CLUE whati did, but it works now!!