When my car is idling, either in Park or in Drive at a stop, I can here a clicking sound like something switching, and my RPMs will go up by 50 or so.. then after a few seconds it'll click again and it'll drop by 50 or so. It'll do this repeatedly... The RPMs stay at around 600-700 for all of this.

 

Oh, and it's a stock L98.

 

What your describing sounds like what mine used to do. I think it may be your cooling fans. Are they electric? Before my engine swap, my car did exactly the same thing. It doesnt do it anymore, but I have a new battery, new alternator, and new engine.

 

If it's the cooling fans, is there some way to fix it. It's getting annoying when I'm waiting in the line at a drive thru. The click occurs every 5 seconds or so.

 

A/C compressor?

 

AC is rarely on.

 

Maybe the A/C compressor is cycling on and off when it shouldn't be. Watch the compressor while you're idling in park and see if it it turning on and off.

 

I hardly know TPI, but I thought someone once said something about the fuel injectors.

 

Yup, it's the AC compressor. Thanks for the help!

Just a couple of quick questions...

Should the compressor be cycling when the AC isn't on?

Should it click on and off that often? I had to drive around for about 15 minutes to get it happening. It would turn on for 4 seconds, then shut off for 8-10 seconds.

 

The compressor should not be cycling unless the A/C is turned on (or the Defrost setting).

Anyways, it should never cycle every 5 seconds even if it is selected. That's way too quick.

First thing I'd do is borrow a scan tool and see if the ECM is requesting the A/C clutch to be turned on and off or if it is doing it on it's own. The ECM is the only thing that should be able to turn the A/C compressor on and off. So if it's doing it on it's own you have electrical problems.

I suspect that the HVAC controls in the dash have gone screwy on you, however, if I had to make an educated guess.

 

Right... A/C is supposed to run when the control is in defrost.

It shouldn't cycle like that. If it does, it's because it's very low on Freon. It has a low pressure switch in the low side of the system that cuts the compressor off when the pressure falls below about 25 psi, which basically will never happen when the system is full.

 

Thanks for the help!

 

Would there be any problem with disconnecting the wiring harness to the AC compressor so it doesn't come on? I would think the constant cycling isn't helping the clutch in it, and it does get annoying. It would be nice if I could disconnect it until I had the time and money to try and find the problem (got other problems with the car at the moment...).

 

Would there be any problem with disconnecting the wiring harness to the AC compressor so it doesn't come on? I would think the constant cycling isn't helping the clutch in it, and it does get annoying. It would be nice if I could disconnect it until I had the time and money to try and find the problem (got other problems with the car at the moment...).

Oops... sorry for the double post... hit refresh on my browser..

 

No, you will not hurt anything if you unplug the compressor. When I used to live in NY I would unplug it during the winter cause I did not want the compressor comming on every time I used the defroster. Also is sounds like your AC is getting low on freon and soon you compressor will not engage because of low pressure in the system.

 

Which is what RB83L69 just posted. Did not mean to be repetitive.

 

Went to unhook the wiring harness from the AC compressor but found two harnesses going to it. One at the back of the compressor, and a smaller on up towards the front where the pulley. What is each one for? And what should I unhook? (I suppose I could have just unhooked them both, but I don't like guessing.)

 

I would unplug the one that is just behind the pulley, that is the one that engages the clutch on the compressor. The other one is a high pressure cut-off switch. (I think)