NO HEAT. 06 XC90 2.5t Thermistor, engine thermostat, and VIDA/DICE questions

[Starlifter]

Hello. My 2006 XC90 2.5 liter t5 puts out barely any heat regardless of temp control knob positions. Even if the thermistor has failed, shouldn't the heat still increase when both knobs are set to max temp? The blower speed does change in response to manual inputs, and airflow is adequate. The infra-red temp of the two hoses on the engine-side of the firewall are 116 degrees F in and 104 degrees out with the blower at max speed, and 116 degrees in AND out with the blower off. This is with engine at normal operating temp and outside ambient at 50 degrees. Are these temps typical? If not, what are the symptoms of an engine thermostat being stuck open? Coolant levels are normal. The engine never overheats, so I assume the system does not need to be burped. I do not know where the blend door(s) are located or how to access or visually inspect them.

Finally, will an OBD2 reader be helpful in heater system diagnosis, or must I have this VIDA/DICE device for trouble shooting? If so, can I rent one, or do I have to buy one? How and where would I get one, and how much would it cost? My zip code is 98374.



Thank you for your kind assistance in this matter!