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Engine stumbles with a/C on

Okay so I have a 2003 Nissan Maxima 150k and the problem that I’m experiencing is that when the vehicle is in drive my foot on the brake for example at a red light and I have the AC on the engine will begin to stumble similar to a misfire however no check engine light will be displayed if I were to turn the AC off and sit at a red light in here with my foot on the brake the car idles fine and smooth the car currentl drives fine accelerates fine idles fine it’s only when I’m stopped with my foot on the brake and the car and in drive with the AC on that the engine stumbles accelerating or cruising any speed above idle with a/c the runs smooth its only at idle and the simple is not predictable it happens often but at random intervals

What I’ve done so far
1.5 years ago I put in iridium spark plugs
Recently cleaned the throttle body its a electronic throttle body
Fuel pump and filter were replace in March 2016
I tested the alternator put a load on it to see if the engine would stumble but it didn’t

My a/C blows cold air and everything in the car works its really a weird problem hopefully someone maybe has run into this before and can help me

There are a few hundred things that can cause an engine to stumble under a load. I would have a good independent mechanic check your engine. It sounds like you may be in over your head here.

Might be the idle air control valve

I had the same problem many years ago, the dealer could not figure it out (under warranty) A friend thought it was the IAC, when we told the dealer to check it they found it was bad and replaced it.

+1 @SteveCBT IAC - bad. Here a link that gives replacement instructions.

Although it probably doesn’t explain your problem here, it’s best to stick with OEM spark plugs instead of changing types (assuming you changed types). That does cause problems for some people.

Things to check. The clutch that engages and disengages the ac compressor. The ac compressor might be stiff and and taking too much effort to spin. When the ac engages the engine idle speed is supposed to increase several hundred rpm. If it isn’t the motor can bog down and idle too slowly.

I don’t know the engine design of your Maxima at all, but on some cars when you turn the AC on the engine computer is supposed to bump up the rpm a little to compensate for the added load on the engine. Maybe that isn’t happening for some reason. This same thing occurs for other reasons that increase the engine load too. On my Corolla for example when I turn on the headlights the engine computer opens a little air valve so some extra air is allowed into the intake manifold to cause the engine rpm to bump up a little. I notice the same thing happens if I turn on the rear window AC defroster. Likewise if I turn the steering wheel the idle rpm increases.

Thanks for the replies guys and sorry for getting back so late but my Maxima has an electronic throttle body so there is no IAC nissan stop using IAC in 2002 on the Maxima models. It simple does not happen right away when you turn the AC on it takes maybe 10 secs then it stumbles and it’s fine again for another 10 secs sometimes when I’m at idle I’ll accelerate from a red light and the stumbles and lacks power but then it’s fine. This only happens when the a/c compressor clutch is engaged. I have tried to replicate stumble but loading up the engine ie. Defroster on all the lights on radio on high blower motor on high and I turn my steering wheel from lock to lock. The computer does compensate for the last pad and bring the rpm up. So it’s like something in the a/c compressor circuit is causeing the issue but what??

If it isn’t just that the computer isn’t bumping the idle speed a little to compensate for the extra load on the engine when the AC compressor kicks on, then it’s either that the AC compressor needs service, or the engine isn’t able to handle that extra load like it used to and needs service – a tune-up w/ new spark plugs or the like.

Try cleaning the electronic throttle body with throttle body cleaner.

But don’t open the throttle plate manually to clean the throttle body.

Instead, have someone turn the ignition switch to on so the dash light come on. Then have them put the accelerator pedal to the floor.

The computer will then open the throttle plate in the throttle body so it can be cleaned.


I’m going to try the new plugs because the ones in there are not NGK plugs which are the factory I believe there Bosch

There are lots of complaints on the internet about Bosch plugs working poorly in Japanese engines.
OEM (NGK or Denso) are your best bet.

I hope by tomorrow Carolyn has banished this spammer