Recent deluge here in FL had our '06 HHR driving through some deep water, not deep enough to get into the intake, however the idle is higher than normal now (1k rpm), the car is vibrating like it has bad motor mounts, and the A/C compressor kicks on and off constantly with the A/C on. The compressor is the lowest accessory on the motor and was probably under water for a period of time, is it possible the compressor is causing the symptoms? The idle remains high whether the a/c is on or off.

Thinking about resetting the ecu but I'm not too hopeful that it will do anything. Any ideas on what it may be?

 

Try it and report back.

 

Reset ecu, no change.

 

My guess is water in one or more electrical connectors. Disconnect each one and dry them out.

Or, water on one or more sensor.

 

The A/C has a pressure sensor that normally shuts the compressor off when it is at its top pressure. A short could easily be resulting in false signals...

So, yeah, basically, what that guy ^ said...

 

If the compressor was under water then so was the crank and it's sensor. Those might be the first connectors to start with.