Whenever I have the AC on there's this loud engine knocking noise. When I turn it off it's fine. I've taken my car in 3 times before for this issue, has anyone else had a problem with this? I'd like to actually know what it is myself before I take it somewhere so I can give them something specific to look for. I don't really have another Mazda dealer in the area to take the car to, so I'd need to take it to an Auto Repair shop, and with the RX-8 being a Wankel I'd like to give them exactly what needs to be done...Just in case they don't know anything about the engine like my Dealership does.

Anyone have any idea what the problem is or has experienced it before?

It kind of sounds like the noise the comes from old deisel cars, really loud knocking sound.

When this does happen it's really sluggish at lower RPM's and the RPM's fluctuate, going up and down at idle, and there's a loss of power (from what I can tell). BUT when I turn my A/C off everything is fine.

 

You brought it in 3 times and they said nothing was wrong? WTF!

Motor mount?

 

I wish.

It's like a knocking/pinging noise. I know I'm not alone I searched the forums but the threads I wandered into everyone tossed out idea's but none of them were like "OH THATS IT". The most commonly mentioned one was maybe the cat is backed up? But why would that cause engine knocking/pinging??

 

you took it in 3 times and the dealer cannot replicate the issue?

i know an a/c puts a lil strain on the motor but it shouldn't be that much. you may be in the early stages of engine replacement.

 

Have the AC compressor checked.

 

I had some a/c issue yesterday as well. when it was turned on I could hear what sounded like a clicking that got louder as rpms rose. Any ideas what that could be? Went away after a few minutes and haven't noticed it since so maybe it's nothing.

edit: clicking noise came from the glove compartment too.

 

I had have this issue as well. I noticed it only happens when the temperature is above 105 degrees at least on my car that is. Not only did I get the loud knocking my A/C died in the severe heat of Las Vegas 115+ degrees. But once I got back into lower temps the A/C stopped knocking and was nice and cool again. I am taking my car in for it's 20,000 mile check up and will mention this too them and see if they can find.

 

I have the same thing going on! I had the motor mounts replaced because of an unrelated rattle but that didn't fix this issue. I cant wait to see what the answer to the problem is!

 

Taking it in soon, so I'll keep you guys updated

 

I took my car in today and they found a bad part in the A/C unit I will find out what the part is and what the problem was and report back later this evening.

 

They apparently are replacing the Temperature Control Unit on my car. I don't think that will fix the problem but I will find out next month when I go back to Vegas.

 

I'm curious about this, do you think it was the Temp. Control Unit? I might be having a similar problem. I get the clicking noise when my AC is on, but I also have the mazsport cooling fan mod (which works well at keeping engine temps. down). My AC has never died and it works very well.

Just the clicking noise is curious, so I'm trying to figure out why.

 

That's a drag. If it were my car, I'd drive an hour or so to another Mazda dealer. Maybe you could combine that with visiting friends/family or doing shopping in the town where there is one?

 

Do you have an aftermarket pully?