Just came down the M1 and there was some traffic were the speed was about 30 mph and suddenly the temperature went up .... Once the traffic eased and I was back to cruising speed the temperature leveled out at just just over 80 which is normal for my car. My guess is thermostat ?! Also, the warm air outlets in the car blow hot and suddenly go cold. When I switch the heating off and after a few minutes on again it blows hot for a while and then cold on pax side but driver's side is lukewarm to warm .... Any suggestions what else it could be are much appreciated !!