I have an 89 300 se and have had the brushes replaced in the blower and the armature check out to be in good condition. Sometimes the heat is pretty good, other times it blows some, but you are still cold inside. What should I check first? Should it be the hose behind glove box or mono valve or thermostat? The temp gauge usually about all the time, whether sitting idle or driving 65 mph is between 80-85. The heater air seems to be warm, but not hot likd it should with the temp dial on max. Can you help me find a solution?

Scott