a real tuffy

[johnboy1]

ok, this one is for the real hard to the core techies on the board. i have a 1980 2wd toyota and when i first bought it the heater worked awesome. but in the last few weeks its been less than pleasing. now here is the conundrum. it blow nice, skin burning hot air on the passenger side defrost vent but ice cold fresh from alaska air on the drivers side. why is it doing this? after probably 90 minutes of running the heater full bore on defrost on recirculation it will blow hot air agian on the drivers, then about 10 minutes later it goes back to cold. my only thought is my heater core is bad. any ideas?

 

[Moneypit1]

Check the vent linkages and check for a vacume leak. A lot of heater systems use a common vacume supply into a vacume block with individual vacume lines to open and close the gates that control air movement.