Chevy HHR Network - Where is a Ground connection for a cooling fan?

HI, everyone
My problem is with a cooling fan.
About a week ago I noticed the my cooling fan would not come ON while I have AC ON or at high Temp. I checked the fuse #40 (good), I checked the relay #50 (good). Its clicking when the PCM request the fan. I had over 14 volts at the wiring harness at the fan connection.
So I thought I needed an new fan.
I bought a new fan and installed it. SAME PROBLEM. Fan will not run.
So I thought What if , just may be I have a bad ground connection, since I did have a voltage reading at the harness.
SO I got a piece of a wire and tapped into a ground (black wire) at the fan harness and then connected that wire direct to the chassis.
Now the fan works just like it should. AC ON, fan is ON,. Temp goes to 217F fan comes ON.
SO it looks to me like I had a bad ground connection.
MY question is : Does anyone knows where is ground connection for cooling fan on chassis? I do not think there is a fuselink on ground wires. Am I right?
I cleaned 4 ground connections that I found under the hood. 1st to the left of Oil filter. 2nd just behined frond driver head light. 3rd above the Thermostat and 4th in front of driver side strut tower. Cleaning did not helped. I did not cleaned the 5th ground that is to the left of driver strut tower.
Fan only works with my direct ground connection. I want to fix it right so if any one knows where is the connection please let me know.
If you have any other thought please feel free to share.
Thank you.