A/C is killing my idle

[percvdrlty]

Please allow me to begin with the current issues and move backwards from there.

It is finally summer in Denver, which is apparently a fine time for my air conditioner to quit on me. Driving to the mountains last week I noticed that I was getting warm air blowing in with the A/C on. The next day, the system seemed to work fine. My hunch on this point, based on other posts, was that my clutch gap is too wide. But then, I got in it a few days later in the heat of the day (2pm, 93 degrees outside), turned on the a/c. When i came to my second light, the idle fell way low. As I pressed on the accelerator to go, she suddenly died and wouldn't restart until I actually turned the a/c system off. Since then, the same thing has been happening. I can run the fan, but the a/c will kill the idle while driving, then the engine when I come to a stop.

What is more, as I turn the a/c switch on, my "up" arrow light comes on, which I assume is a recognition of the drop in idle speed and an indication that I am in too low of a gear.

Some recent work:
Having just bought the car this spring, I was disgusted that the previous owner put several drywall screws and nuts/bolts through the dash in various places in an attempt to fix the squeaks (broken dash mounts?). I recently removed the one he placed in the center of the dash (could this be why my SRS light has been on?). Perhaps it punctured something? I have yet to put the screw back in to check if it has an effect on the A/C system.

I also just re-soldered in a used rear O2 sensor wire harness, but the wire gauges didn't match on the number 2 pin. My CEL has been on since the second day I have owned the car (mostly related to the o2 sensor).

So, I am quickly learning volvo's, but I need some direction on where to start on this a/c issue and what to look for/test for. What do I need to look for when seeing if the clutch is engaging or not, or if the condenser is shot? Could I be looking at replacing the evaporator, especially since I have leaves blowing in each time I turn the fan on? I am fairly mechanically inclined, but new to sweden, so any specificity will be very much appreciated.

My car is a 99 V70 GLT turbo with the 2.4L.

Thanks

[Ozark Lee]

You have a number of issues that are seemingly unrelated but the drywall screws trying to secure the dash could certainly relate all of them. The main wiring harness for the dash and on out to the engine runs around the top of the dash on the '98 and earlier models and I believe it is similar on the later models. God only knows what wires are being shorted out if the harness got clipped with a screw.

The good news is that the wiring itself is easy to fix when you find the problem areas - the bad news is getting to them. You will likely need to yank the dash and properly repair the dash mounts and at that point you can locate the areas in the harness that have been torn up. If you go that far you might as well go ahead and replace the evaporator since you will have done 90% of the work required to get to it.

When you replace the evaporator you will also need to replace the accumulator/receiver/drier and have a vacuum pulled on the system before recharging it with R-134A.

...Lee

[jblackburn]

The AC/idle issue, sounds to me though like your ETM is on the fritz. It is responsible for controlling the idle and well...everything to do with the throttle...on the newer models.

Take a listen to the sound of the car running with the compressor on, you'll hear a slight whirring and a load on the engine. When the AC cuts out, I'm guessing you won't hear that. Stick a stick down in there and press on the side of the compressor wheel; if you can get it to engage again, you're right on with the clutch.

My Saab used to do the same thing with the AC running (well, when it worked anyway). It was fun, you had to hold the idle with your foot at stoplights and then try to simultaneously work 3 pedals at once, try not to stall or smash into the cars behind you on hills