I own a 2013 C70 for the last 2 years. My problem is the fact that even when the temp setting is set low, I feel warm are coming from the duct. I had the Heat/a/c sytem check by a Volvo dealer twice and the reset all system motor and the tell me that everything is ok. I noticed there is no valve to bypass the coolant from the heating core. Is there anybody found a solution to add a bypass valve ( not a shut off valve that would prevent the coolant flow back to the system and create over heating the head of the motor) I believed adding such a valve would solve the problem.