I have a very strange problem with my 2010 Toyota Camry - if I turn on the A/C or turn it to the defrost setting, then when I put in the clutch (it's a manual) or stop the car the engine starts to run very rough and eventually will start ticking like a fan is hitting something. If I'm driving around I can turn on either without noticing a problem, but it's awful if the car is moving slowly or stopped. Has anyone experienced this before?

 

What engine type, 4-cylinder or V6?

Has this always been a problem?

With A/C or defrost on, the A/C compressor will cycle on and off and placing a load on the engine. The engine computer should adjust the idle up when the compressor runs but may not be here.

For starters try cleaning the throttle body, the internet has posts on doing this. Use only a throttle body cleaner safe for plastics.

The rattle may be the timing chain.

 

Thanks very much for the help! It's a 4-cylinder, and it's only been going on for a month or two. Right now I'm just not running the A/C and driving with the windows down, but living in Florida it's not the most pleasant option.

I'll try cleaning out the throttle body tomorrow and update the thread. In case anyone having the same problem finds this thread, here's a helpful video on how to do so: Camry Throttle Body Cleaning - YouTube

 

Thanks for posting the video, looks good. I know that I need to do this as well.

 

Well, there is good news and bad news.

The good news is that, pending additional testing, cleaning the throttle body seems to have fixed the original issue! I re-assembled everything, took it for a spin around the block, and then sat idle in the driveway for a minute with both the A/C and the defrost setting on with no ticking sound or engine struggle. Many, many thanks to toyomoho.

The bad news is that, after that, I disconnected the negative terminal of the battery to reset the Check Engine light per the video that I posted. I was rather unpleasantly surprised to find that as soon as I re-connected it the horn started going off. Apparently I had unintentionally activated the theft deterrent system. I tried re-connecting and then unlocking the doors, but that did nothing, and I tried starting the engine, but that also failed to stop the alarm. It also seems to turn over, but then quickly stall out unless I give it gas. Those are the only two methods noted in my manual for turning off the alarm. Any other ideas, or perhaps some pertinent details about stopping the alarm the manual might have glossed over?

 

Okay, I got it squared away. Here's what I did:

Right after writing the last post, I decided to go disconnect the horn and see if that would allow me to operate the car or potentially do some more debugging. I live in a pretty quiet neighborhood and I personally despise being a nuisance, so I disconnected the horns (found out there are two!) and reconnected the battery. You can still hear the relay switching for the alarm, so you know that it is still active, but it's not waking the dead anymore.

At this point I could more leisurely attempt the same deactivation methods I had tried before. So I started the car, gave it some gas to keep it going, and then found that after ten seconds or so I could no longer hear the relay triggering and the car was idling just fine. I guess that I just needed to wait a little longer? Anyway, all seems to be well now, and thank you again for the help!

 

Glad to hear you got it squared away and posted back with the fix.

 

Alas, it seems that I spoke too soon. While it is certainly quieter now and takes longer to appear, the idle still gets to be really rough when stopped and I can occasionally hear the ticking, too, though I haven't really let it get too loud before I turn off the A/C.

Any other ideas?

 

Reconnecting the battery sets off the alarm.

If Toyota alarm use FOB to turn off. Or try locking and closing all doors then unlock drivers door with key or key FOB.

So, the engine runs OK at first then becomes rough? Engine when cold will idle at higher RPM. Perhaps when idle drops, the problem appears. What is the engine idle when running rough?

Disconnecting the battery can cause idle issues as the throttle is electric.

Can't reset codes by disconnecting battery. Need code reader to do this.

Ticking still could be the timing chain or perhaps serpentine belt tensioner. Use a section of hose as a stethoscope to narrow down problem area.

 

When I stop at a light, the engine initially seems to idle at about 1000 rpm, and I don't notice the sound or roughness. Then it drops, generally once to 800 rpm and then again to 600 rpm. After the first drop below 1000 is when I notice the roughness and the ticking sound.

I don't know about setting codes - the instructions that I found for cleaning the throttle body indicating that the process would trigger the Check Engine light, which it seemed to, and that this could be reset by disconnecting the battery for 30 seconds, which also seemed to work. Unfortunately, the alarm problem was a side effect. I'll try the fob next time; I don't generally have it on me, but I think it's somewhere...

I'm going to have to try the stethoscope thing in a week or two since I'm going to be out of town the next few weekends. Thanks for all the help!