New owner lots of questions 1999 s-80 volvo

[dan1959]

Afternoon,
Recently aquired a 1999-s-80 t-6 turbo volvo from a estate sale 143kmiles. The car has some issues i like to share and see if i can get some feedback on.First off it dont have a engine "temp reading" for the engine, stays pegged on the cold side. Did some troubleshooting and replaced the ECT with a direct volvo ECT. Still no temp reading ..also the a/c compressor does not engage the light comes on the dash but dont engage the clutch. its my uunderstanding with out the ECT signal the computer shuts down the a/c and several other items base timing a/c compressor cruise. etc.. does anybody have any idea where to head next for the no temp issue..?I have phycally check the wires from the ECT to the computer and I have 12volts and ground to the sensor.. I also have the engine soon light and the stc service soon light on in the message window( lower left)and caution panel (lower right) on dach. I have tried to reset theses codes using the dash reset procudures and by using a generic code reader.. the codes erase and clear the panels but return the minute the cars is restarted..Do the codes have to be reset using a scanner with volvo software? I was led to belive the generic code reader will not erase a HARD code set in the ECM and since the hard code is still present, the ECM dont realize the ECT has been replaced... The car also has a hard stumble(from which i was told was base timing).The previous owner had the timing belts put on 3 months ago with non of theses issues present.. Theses issues came up once the No temp indicaion was on the dash.The trans fluid was black .. I changed the fliud and filter and flushed the torque converter and cooler using dextron 6 fluid. What i dont know is does the trans axcel use the same fluid as the transmission or is it a seperate system? thanks for your time and i hope i wasnt overwhelming with questions. /r dan