AC/Coolant/Thermostat Questions

[Chris_s1]

Started car and let it run for a little bit after reinstalling dash. Car hasn't been running very much at all since I changed the timing belt and all related accessories. I also tore apart the interior and I'm swapping in a new one. Once I got the dash in I turned it on and let it run, seems to be running fine, burned a little oil on startup, running smooth. However, the AC is colder on the passenger side than it is on the drivers side by a few degrees, but it's a noticeable difference. Any ideas? In addition, once the AC was on, I could here a clicking coming from the engine bay. My guess was thermostat but I'm not 100%. Didn't make the noise when the AC wasn't on. I do have a few codes (P1620, P1690, P1676) all related to the coolant temp sensor, which is plugged in.. Anybody have any ideas regarding any of these issues? Thanks for the help in advance!

[Chris_s1]

Replaced coolant temp sensor on a cheap and easy whim, lets see if that makes any difference when I start her up tomorrow.

[02 A6 2.7T]

Replaced coolant temp sensor on a cheap and easy whim, lets see if that makes any difference when I start her up tomorrow.

Did you replace the one on the lower rad hose that controls the cooling fans ?
The one on the back of the engine is only for the temp gauge ...

[Chris_s1]

This one correct?

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[02 A6 2.7T]

This one correct?

Sent from my HTC One_M8 using Tapatalk

Nope, that's the outside air temp sensor that displays in the center LCD on the cluster ... you should be changing this on the lower rad hose: https://www.ecstuning.com/Audi-B5_S4...Engine/ES1873/
which fits here :
https://www.ecstuning.com/Audi-C5_A6...oses/ES429382/

[Chris_s1]

Damn! Thanks man. I replaced the one on the block and then I had that one^^ left to connect. Thanks for the link, I'll replace and report back.

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Any idea if that could have any bearing on the thermostat clicking?