Volvo: Thermostate replacement, volvo s 80, climate system

Question
1999 Volvo S-80 T6  215,000 miles.   I only have heat when the engine is above 1300 RPM, otherwise it just blows cold.  I thing the thermostat is bad but can't seem to find it on the engine.  Where is the thermostat and do you think that may be the cause of the "no hot air at low RPM".

Answer
Al,
The t/stat is behind the t/belt cover. The housing is below the two top gears. You can use a scan tool to read the engine temp to see if the engine is in fact warming up to operating temps. That way you know there is no problem in the climate system.
Also be sure that the coolant is filled to in between the Max/Min. marks.