Sc400 Heater/ac

[bquietroy]

I have a 92 SC400 with two distinct problems that may or may not be related. Heater blower quits working sometimes after selecting another setting. An example would be that after driving over an hour with heat and blower, I changed to defrost and lost heat and blower. If I park the car and let it sit a day or so, all is fine when I drive again. During the summer the AC cold air will drop to a warmer temp for no reason after driving for over 30 minutes. No matter how low I set the temp the air temperature stays the same, not real cold, but not warm either. Again, stopping the car and letting it sit for a day or so, gets it back to cold air and operating normal. Both problems do not happen all the time. It may depend on length of time I drive, or if I change settings. I also noticed that the air is colder on the passenger side vents. The two vents on the center of the dash have different temps when there is a problem. Anybody got any ideas? Tim