While cruising at low speeds with the window down or when idling, I have been hearing a click from under the hood that happens every 20-30 seconds. Big click like an A/C compressor kicking on, but without it being turned on (nor the defrost). I think I can even feel the click's vibration in the gas pedal. I would think it was a fan relay except that we've had cooler days lately, and I don't hear the fan running nor does it run after the car's turned off. No CEL or other symptoms that I'm aware of.

Is there some loud relay under the hood that is known to malfunction, by just clicking loudly again and again?

 

The click is the type that seems to add load to the engine. Does that narrow it down?

 

My car does the exact same thing. I could be wrong but I think it mostly does it when the engine is still cold and at low speeds.

 

It clicks when cold and warm. Sounds like a big relay being thrown similarly to an A/C compressor. I plan to pop the hood and listen out to find where it comes from.
Could the alternator click in and out of its cycle like this?

 

i have this same problem...you ever figure out what it is?

 

I think the noise you all are hearing is just the air conditioning clutch on the compressor, cycling on and off. When the clutch is energized, an electromagnet pulls two parts of the clutch together, locking them and transferring rotational motion to the compressor. Sometimes when the clutches get older, the clicking may become more pronounced. If your system is leaking refrigerant, the clicking may happen very frequently. If too much leaks out, the clicking stops altogether and you get no cooling.

 

thanks...sounds like it's me...how can you check the fan relay to make sure it is working properly?

 

How can the A/C compressor be energized when it is not turned on?

 

Nonetheless, sounds like the AC. Is it possible you have the climate control in defrost? That energizes the compressor.

 

I know you are trying to help, but please read my first post. I said it sounded like the AC compressor, but neither AC nor defrost were activated!

 

I had the same problem some time back. It was the throttle body connectors not making good contact and the TB relays clicking on and off. I cleaned both male and female connectors to the TB, put some dielectric grease on the pins and the clicking disappeared. Try it.

 

Well, does it make the noise while the car isn't moving? Such that you could look under the hood with the engine running, and try to localize the clicking?

 

As he said, " He feels it in the pedal" which to me is corilated with the TB.
Unfortunately, I too am having this same issue and its a rapid on/off rackit for lack of a better description. Just this morning it was really loud and could hear it through the fire wall with everything off so i popped the hood and felt it right on the TB. I even video'ed it so I had evidence, lol.

 

Occams Razor...........always go for the simple answer first.

 

I have not tried locating the sound yet, but HurQ, you've def supported the TB theory. So if I understand correctly from Dinger, the TB's electrical connectors are either loose or dirty and need a clean, lube and tightening. If this is the case, I would probably stand to see better fuel mileage too. I will investigate soon. Thanks