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SHIFT_FASTER
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Discussion Starter #1
A/C Causes Stalling

I have been having a problem with my A/C for a few weeks now.

Normal A/C operation (per service manual):
-Idle with A/C compressor not running: 650 +/- 50 RPMs.
-Idle with A/C compressor running: 700 +/- 50 RPMs.

My A/C operation:
-Idle with A/C compressor not running: 650 RPMs.
-Idle with A/C compressor running: drops to 325, sometimes lower, sometimes enough to stall. Sometimes the A/C compressor shuts off due to low RPMs (< 300), then as soon as the RPMs return to normal, it turns back on again.

For the first 6 months of owning the vehicle, it did exactly as it should. Now the problem is consistently repeatable. Told the dealer to look at it, but they weren't smart enough to check for the problem with the A/C switch on. :3:
 

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Something is off... any new information on this? I've never heard of this issue on the MO.
 

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You REALLY need to get a new dealer, Taylor. You are having entirely too many problems.

Anyway, I don't know how Nissan does this on the Murano.
There are lots of different ways to do it.
"Probably" it starts with Computer control, but not necessarily.

In any event, the only thing that would make any sense for you to do, would be to raise the hood and follow every vacuum hose to see if one has come loose (Or was taken off when one of your inept mechanics took it off when looking for sensor problems.......)

That's a big problem when dealing with a bunch of overpaid, under trained mechanics. They break more than they fix and it seems as if the car is falling apart right before your eyes.

In any event you are having a problem with your "idle speed motor" although Nissan may use slightly different terminology.
I's job is to control the air allowed past the throttle body when there is a load (AC Clutch) on the engine.

Hope this helps.

Homer

I would bet that your problem started right after you had it in for another problem. Might not have noticed it tho as you likely don't fun AC too often in Canada in JAnuary.:cool:
Any mechanic that doesn't turn the AC on when troubleshooting an AC idle problem is completely inept.
 

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Sounds like you have an idle problem. The Murano uses an electronic throttle which regulates the idle speed by working in combination with the idle air control valve. If your IACV is defective, you'll have idle problems. The AC places a load on the engine, decreasing engine RPMs for a given amount of throttle input. So, the ECU should see that and open the throttle a little more to keep idle speed normal.

Take your car to the dealer and show them the problem. If you can reproduce it, they will repair it. Unfortunately the monkeys at the dealership seem to have terrible diagnosis skills for reproducing problems, so make sure you can show them exactly what the problem is, or you'll be leaving from the dealer angry and frustrated.
 

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SHIFT_FASTER
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Discussion Starter #5
I've had it to the dealer twice, but the first time I didn't know I was dealing with (what seems to be) two problems. I'm not sure if they both showed up at the same time, or if the A/C problem showed up after they looked for the other one.

The problem with the A/C is repeatable, but I made the assumption that the tech would turn the A/C on and see the RPM drop. (You know what they say about assumptions. :rolleyes: )

The other problem, only occurs when I'm driving and it's snowing. I don't know what to do about that. My dealer only books appointments more than 4 days in advance, and the weather forcast is rarely accurate more than 3 days in advance. I see a big snowstorm on the way this week, maybe I'll try to get an emergency appointment.
 

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I don't know where you are in Ontario but you've GOTTA get to a different dealer. If you're around TO, try sending a PM to jaak for a dealership referral. There are other Ontario-based MO owners here on the site -- Rainbowfarm is one around Ottawa and I'm in Kingston. Either way, find another dealer. Yours sounds like a complete ass.
 

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SHIFT_FASTER
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Discussion Starter #7
Already done. I'm in Ottawa, and there are at least 2 I know of. The nice part is, the one I'm switching to is between where I live and where I work.
 

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Let me know your thoughts on them. I may be getting transferred up your way this summer or next, and will need to know who to see and who to avoid.
 

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Discussion Starter #9
I'll post an update after my next appointment (which I haven't set yet).
 

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Discussion Starter #10
Homer or Eric: is the idle air control in use during normal (non-idle) driving conditions? Because I just noticed the problem occurs when I'm not idling as well, although above 1500 RPMs, it no longer causes a drop in RPM, but I can really feel it in the power.
 

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The IACV functions only to maintain the idle speed I believe. A huge malfunction in the system might affect drivability, but I cannot see how. If you are experiencing a power loss above 1500 RPM, I suspect its a fuel, spark, or maybe even a CVT problem. Either way, it would be a good idea to have the dealer check for codes.
 

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I concur completely.

Homer
 

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Discussion Starter #13
No codes, checked twice. Plugs were fine a few thousand miles ago. I suspect the A/C compressor is putting too much of a load on the system for some reason.

It's possible the CVT is causing a problem, and it could be my other problem is related.
 

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Tyler_Canada said:
No codes, checked twice. Plugs were fine a few thousand miles ago. I suspect the A/C compressor is putting too much of a load on the system for some reason.

It's possible the CVT is causing a problem, and it could be my other problem is related.

Sometimes the simplest answer is the correct answer. We know the AC is connected to the various accessory belts, and the accessory belts are driven by the crankshaft which is in turn connected to the timing chain. What if...and I'm going out on limb here...the AC belt tension is off due to either a bad belt, defective pulley, or defective belt tensioner, that could conceivably have a chain reaction that might affect not only idle speed, but also drivability at 1500 RPM.
 

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Discussion Starter #15
Another thought I had was, what if I had an intake leak? It would cause problems with idle, probably problems with drivability, and misfires when snow gets sucked in.

The first thing I'm going to do, is change back from my K&N filter to the stock one. Then, if either problem is still there, time for another trip to the dealer.
 

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Tyler_Canada said:
Another thought I had was, what if I had an intake leak? It would cause problems with idle, probably problems with drivability, and misfires when snow gets sucked in.

The first thing I'm going to do, is change back from my K&N filter to the stock one. Then, if either problem is still there, time for another trip to the dealer.

Aha! The K&N filter. Its quite possible oil from the K&N gunked up the MAF sensor. That will certainly affect idle and all around drivability.
 

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Discussion Starter #17
Not the A/C

So for the first time last night, I had the problem occur with the A/C turned off. It seems to be the alternator causing the problem. I had the headlights, rear defrost and brake lights on, while waiting for a car wash. When I turned the rear defrost off, the problem went away. When I turned it on, it acted like I had turned on the A/C. I think the A/C just made it obvious, because the fans come on when the compressor does, creating a lot of current draw.

Has anyone who had an alternator fail noticed the engine RPMs dropping when idling?
 

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Discussion Starter #18
No, I'm pretty sure it's not the K&N (MAF). The engine runs great, idles great, except occasionally. I wish I had a voltage gauge.
 

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I had the same thing happen to my Jeep wrangler after about 3000 miles. When I put rear defrost, wiper or a/c on I would drop down to 500 rpm and would sometimes stall. Especially when I was stopped. Dealer ended up replacing alternator and the battery. Hope this helps.
 
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