Hello,
I finally got a Gentex Homelink, auto-dimming rear view mirror working like stock. My 07 has a plain rear view mirror with map lights.

For those who dont know what Homelink dose. It can control your garage doors, House lights or driveway entry gate.

I started out looking for a Homelink mirror and a map light was a must. I chose the Gentex-341. Its an older model and the same model in my SSR. So I thought......

I later found out that there are 3 differnt Gentex-341 mirrors.

My 1st purchase was a 341 for a Toyota Scion XA. It has a map light/homelink and mounted right up. But I couldnt get the map light to come on when I opened the door. I contacted a person on the web who told me if it has a 2 differnt color mood light it will not work. He was right. The map/mood light was amber and blue. Big FAIL on my part.

I then tried my SSR 341 Mirror. I thought it worked in my truck it should work in my HHR. NOPE the map light wouldnt work either. The SSR has a amber mood light.

I was told that a Gentex-341 Homelink with compass/temp would be the only one that would work. It has no mood light, but the circuit to control the auto-dimming map light function. So I found a Gentex mirror from a 2004 Chrysler Sebring and it worked.
The Homelink and Auto-dimming. Map light comes on when door opens and auto-dims when exiting.

I still have to get a temp sensor. I proly put the temp sensor inside the cab, since the HHR DIC reads outside temp.

The commpass/temp readout is amber color. I think I can change this to match the green cluster lights?

Heres a good link for Gentex Mirror info:

Testing phase :)

 

nice. For your temp sensor, you can probably just tap into the existing temp sensor which is located underneath the front passenger headlight.

As far as the readout you probably can't chnage this, because it's probably not a bulb or LED. It's probably a DOT Matrix Display. Sorry mate.