My 00 started not going up to temp about 2 years ago....it used to start delivering heat inside after 1 minute drive and now it just does not get hot enough to allow 4th gear (A/T) .....and yes, I use an obstruction to block air to the radiator and temps goes up, and then I have heat inside. Yes, I know I should simply change the thermostat but , well, I satisfied with the present solution. No problem in summer.