I found a greenish liquid under my driver side floormat - cannot think of anything other than coolant. No odor detected. Volvo mechanic says he checked the core, hoses and gaskets - found no leak. He replaced the thermostat and I have had no more moisture. My thoughts are as follows:
1. I have not used the heater since the "repair." Should I use the heater and drive for awhile?
2. Could he simply have missed the leak?
3. What would the thermostat have to do with a leak?
4. Totally honest guy - complete trust in his honesty.
Could really use your thoughts guys............

 

The thermostat would not have much to do with it unless it was broke and building extra pressure.

I would turn the head on and see if you smell coolant.

The o-rings for the pipe might be leaking.

I would have it pressure tested.

 

Thank you for the reply.
jim