A/C overheating engine, $7000 in repairs, 2001 V70 2.4T.... why? (for a good friend of mine)

Alright.

Friend of mine has a perfectly fine 2001 Volvo V70 2.4T that was on lease.
She (and her family) drove it for 104K Kms, couldn't find another car to
fall in love with for a new lease, so they decided to buy this one....

AND THEN

She had to spend $5000 on repairs relating to the DSTC system, fix the
brakes, a potential problem that could have caused a fire... she didn't get
into the details, she said mainly the brakes (I think all the sensors were
screwed). Included in that $5000 was all the other unschedueled repairs,
including sub-CPUs in the multiplex system screwing up, with the rear locks,
alarm, and lights (rear lights). They told her the computer in the trunk of
the car was messed up, now microcode had to be downloaded from sweden.

NOW

The A/C system decided to screw up, and it caused the engine to start
overheating... $2000 later it is fixed... I think Volvo installed a new A/C.
Why on earth would the A/C put such a load on the engine? isn't it just belt
driven? I thought the A/C coolant was different from the engine coolant etc
etc etc... I know A/C brings up the temps on the engine slightly, but even a
failed unit shouldn't cause a car to overheat right?

So they have spend $7000 on this car, and hope it will last a very long time
now that they have fixed just about everything on it. But it leaves them
asking, what the hell is wrong with this car??? It is the first model year
of the new type V70's, are they known for problems?