Hi everyone!

I'm having 2 seemingly separate issues with my 2,5 liter turbo engine(B2554T in a 2000 model C70). The engine warms up and the cooling fan never kicks in, the engine of course continues to warm up until 100 degrees Celsius(212 F), in witch point I'm forced to shut it down. I've tested the thermostat to be functioning properly (Opens at 90 C/194F) and I even bought a new one to be absolutely sure.

I'm also sure that the fan is in working order, it starts cooling when AC is running. I'm also confident that the water pump is working properly, as it isn't making any screeching noises.

Any ideas on what to troubleshoot next? I tried to make sure there is no air left in the cooling system by draining out about 3 liters(~3/4 US gal) of fluid and replacing it slowly while the engine was running. I have also replaced the coolant and cleaned the system a couple of weeks ago.

The second problem...

My engine is flooded with gas(I guess). For some reason the long term fuel trim is at 19.5%, which I think is way too much. I'm pretty sure the electronic throttle module is working as it does not present any of the symptoms described in various forums online (fluctuating idle, sudden loss of power). The engine will 'hang' for a moment when accelerating quickly at around 3000 RPM and/or above, but I've made an unqualified assumption that it's getting too much fuel in the mixture. Maybe I'm wrong?

I'm thinking that my next step on this issue should be to check all the vacuum hoses for damage (i've had a quick look at them and they seem okay) and to replace Mass Airflow Sensor. Now I have few questions regarding this:

1. Is there any easy way to check those vacuum hoses or do I need to pull each and every one of them out for inspection?

2. Is there any (easy or hard ) way to check if the airflow sensor is working properly or not? My OBD software thinks that all the values are within operational limits, But at the same time it gives me an error code of P1171, that would suggest it's broken. It's a 100€ piece of hardware and I'd like to be sure it's broken before I replace it.

3. Could all of these problems be linked to a faulty temperature sensor somewhere? I'm assuming that the ECU is basing a lot of the calculations and decision making on the temperature. I'm getting all my temps from my OBD software, which I think is getting them from the sensor next to the thermostat.

4. This is not a question, but merely a statement. I don't know much about cars or fixing them, so it would not surprise me if I missed something or made some completely false assumptions. That's why I'm writing this post here...

Please advice which part I should put my money on next? This damn Volvo has cost me a fortune already.

Thank you (in advance) for any assistance.
- Juha