There was no r134 in the system. All I bled out was air. This means leaks... yay, No change in idle btw

Throttle valve looks good, nothing is getting through when it is in its closed position.

I guess now I will try replacing the ICV and the ECU. I hate doing that kind of thing but I don't know what else to try.

Andrew

 

the ecu on your model is made to last forever and i never encounter any defective one before.

try disconnecting it with the engine running and see if it affect the idle speed.

since it is giving signal to the icv, it is working.

the problem must be on the input and not output.

 

That's what I was thinking but I can't find anyway to test the inputs.

Discounting the ECU does nothing.

 

Andrew.
The OVP relay is an On/Off device so I think it is unlikely that this is your problem. Other systems like ABS and Traction Control if you have them are linked.

However, now I have more information I return to why did this happen when it did? You are categoric about the ICV and throttle butterfly working correctly so we will move to a different focus. However you didn't answer whether you could establish different idle speeds by altering the orifice in your paper restrictor. If you can there is still a good chance that the ICV is playing a part

You make the assumption that the A/C pump is OK but your post state that this A/C compressor has never actually been working since it was fitted. Is it the correct compressor etc? It also appears that the system has been down for some period without refrigerant and therefore lubrication. Since I now understand that the compressor has disengaged and won't reengage (the other question I asked in my post) it seems possible that the compressor has seized. Sleepwalker has advised that there are build in safety devices to protect the auxillary drive belt in the event of seizure. These must be initiated thru some form of feedback from the compressor. I do not know what signal is used. System pressure/temp? (possible since this is already being measured, Compressor speed? unlikely.) It is possible that this feedback system is applying the increased idle speed.
Is there a +12v signal being sent to the compressor when you turn A/C on? If so why is the compressor clutch not working?
It increasingly looks like the Idle speed control is working correctly and that you problem lies with the A/C control system.
My suspect is now the A/C compressor/clutch.

Hope this helps in some way. Keep us posted
Stuart

 

Sorry, I know I have a hard time explaining things so i'll take it one at a time:

Compressor was working before idle problem and there was refrigerant still in there when I got the car but not enough to function.

It's possible that recharging the ac caused a crack in one of the hoses to finally tear open.

I had cold air after the first 4oz I put in, but it was more cool than cold... so I put more in. + 2oz of oil

I am assuming (hoping) that the compressor is ok, the previous owner drove it very little with the new compressor because the battery would not hold charge (shorted alternator). I know this for sure as he owns my house...

The compressor appears to be the correct one based on pictures. It was also installed by a mech.

From what I know, when the ac is turned on, the clutch engages and the engine is fed more gas to compensate for the compressor. If the clutch were not to engage, the idle should go up, but up to 3200?

The compressor has a pressure switch to protect it from a overcharge condition. There is another one I believe that detects the compressor operating at a speed lower speed than the engine and disengages the clutch (seized condition). Correct?

On the orifice, slightly opened is 2000, and closing off the vacuum completely after the car is started (hard to do without stalling, took a few tries) the car idles at 800.

ICV has been tested, valve does close a 3V.

Obviously the valve is electrically stuck open, 13V is going to the ICV.

ECU looks good, and sleepwalker says it is indestructable, so i'll rule it out.

So... this leaves the AC and the inputs to the ECU.

I'll take the car the MB dealer on tuesday (payday) and have them diagnois the input signals (basically just the sensors right?). I'll let you know how that goes.

Thanks for all the help so far guys,
Andrew

 

Hi,

Thanks for your patience. Nothing wrong with your explanation. However you don't appear to have followed up on some of the suggestions.

"Extract"...........compressor has disengaged and won't reengage. Is there a +12v signal being sent to the compressor when you turn A/C on? If so why is the compressor clutch not working?

Since problem occurred when you were working on the A/C and since the A/C compressor is not turning it seems likely that the A/C is the problem due to the fact that the A/C system lifts idle when in use (hence the 13v?). Since the A/C system can sense a seized compressor it may be this "safety" system that is giving the symptoms. (I do not know exactly what inputs are used to detect a seized compressor without reference to manuals which are not currently readily available).

I suggest you find out whether 12v is being applied to the compressor when you turn the A/C on and not when it is off. This is a straightforward meter test. If 12v is seen at the compressor can you hear any sort of noise (click, buzz etc) when you turn the 12v on/off?

If the clutch (or compressor) has gone bad then the increased idle MAY just be the way the system fails in order to advise the problem to the driver.

As you correctly state you need to understand why the ICV is receiving 13v since this is obviously elevating the idle.

I agree with Sleepwalker that ECU's are extremely robust unless they or their connections have got wet.

Keep us posted.

Stuart

 

idle speed increase with compressor on is only 350 rpm.

it means that normal 850 + 350, should be 1200 rpm.

since you got 1500rpm, it can be something else.

 

Sorry for taking so long... Clutch is not recieving any voltage. Multimeter was reading in the millivolts with the A/C on and off.

Compressor appears not to be seized as it turns extremely easy by hand (system is empty).

Is it possible that AC relay could cause the high idle?

Andrew

 

Hi,
If the A/C is not receiving any voltage this would indicate that there is something wrong with the A/C control circuits. Will do some research and come back to you.
You state the A/C compressor is not seized. I do not disagree with your statement but if you turn the A/C pulley (without the clutch operational) it will turn freely since you will not be turning the compressor. How can you be sure the compressor is not seized?
Stuart

 

Hi,
Can you send me your email please thru PM.
Done some research and I have a lot of info that I can attach to a regular email message.
It appears that the compressor does have a speed sensing device. The sensor compares input speed vs compressor speed and is used to shut the system down if certain criteria are not met.
Once shut down by a control unit under the hood, which occurs within milliseconds, the system won't work again until an ignition boot. There is obviously something wrong with the A/C on your vehicle or the results that you reported. When you measured A/C clutch voltage with A/C on/off, did you have a fan speed selected. The A/C doesn't work if the circulating fan is off?
Whether your problems are linked remains to be seen but the balance of probability suggests they are.
Your VIN would be useful. I don't have much experience on this vintage of Merc's and have assumed a 190 2.3 is a 201 something.
Stuart