A fast ticking sound about 2 ticks per second almost steady. Only when the key is ON or engine is running. Tried with both fans, radio off but still is ticking. Removed fuel pump relay and fuse and no change. The sound comes from behind the rear pass side panel near the wheel well. Anybody have this sound before ? Thanks. *BW*

 

Could it be the rear Heat fan motor?

 

Could be rear heat mode actuator gears stripped.

 

If so, would turning the switch fully either way make the gears stop trying to turn ? Thanks. *BW*

 

Yes it should

 

Fixed for now. Removed side panel, did the same test but NO clicking and both actuators when felt had a very small vibration. Also found the rear fan low speed not working but two higher speeds were ok. No low speed using either front or rear switches. Removed resistor pack now called a relay and found some cracks in the ceramic looking stuff. Went to the nearest parts house bought one for $112 + tax. Didn't fit, tried all the others in the store and same story. Went to GM dealer and paid $117 + tax and have all speeds now. Success ! Why the ticking ? Dunno but couldn't stand it not knowing so I removed each actuators and took them apart finding NO problem with any of the many small gears. While I had them off I easily could turn the stub shafts for the hidden doors inside with my fingers. Figured they were ok. WARNING : If you take these apart DO NOT loose the orientation of any of the the several small gears or they will be out of time with each other. Look at the three tic marks on the outside of the box for the orientation of the notch of the drive gear. After I paid about $130 I found out online I could have gotten the same thing for about $75 mailed to me. Too bad I was in a hurry. Good luck. *BW*