heater on slightly, outside temperature reading too high

I am not yet convinced that what I am seeing is real, but my 2007 of late seems to be reading the outside temperature too high, and when set to just blow air there is warm air coming out of the vent in either recirc or fresh positions (with T-inside set lower than T-outside). For the first one, this afternoon it was reading 85 when it wasn't more than 75 outside. The car had been in the sun though, so maybe the metal around wherever that sensor is located was warm to start with and stayed warm? Drove it 10 minutes, parked it for 5, drove it 10 minutes more and it was still blowing warm (not hot). Same outlet temp (as judged by feel) for either recirc or fresh positions. Is there a condition where the heat can get stuck "a little on"? A car which has been parked in the sun for a while will tend to blow warm air, but 20m of road time would seem like enough for it to cool off, yet the vent temperature seemed to be pretty constant the whole time.

 

No. When it was reading 85F outside the temperature was set to 75F.

 

Will do next time it is driven. The A/C still blows cold when it is set to do so. Cannot rule out "whole lot of cold air + a little warm air" though!

 

Today we took an instant read thermometer along for a ride. The outside air temperature (in the shade) was 75F. Started the car and it read outside as 78F and continued to do so during the drive. The vent temperature when moving was 87F regardless of the temp setting at "low" or 75F or flow on vent or recirc. The cabin temperature was also 87F. Turned the A/C on with the temp set at 75F and with a low fan and it blew cold air into the cabin. Did not measure that temperature though. The grate area ahead of the windshield on the passenger side where the air comes in (I think) was in the sun most of this time, and the plastic there felt pretty warm. So I'm still not sure. It seems like the heat is "a little on" but I cannot really rule out that the section of the car where the hot air moves isn't just hot from the sun and that that is what is causing the warm vent air.

 

Is there a valve that does that? The only one I know of in the coolant path is the three way valve that shunts hot coolant to the storage tank, and I thought that always sent to one or the other, not to "off".

Seems more likely that whatever door/actuator that controls air flow over the heater core might not be moving all the way shut/open (whichever way this goes) so that it is blowing a little air over the core when it shouldn't. There is some mechanical device under the dash on the passenger side which makes slight groaning noises when the car turns on, perhaps that is it?

That said, this morning it was 65F out, the car had not been in the sun, and the air out of the vents felt very close in temperature to the outside air. No thermometer along for this ride to provide actual numbers though.

Makes me wonder if what I saw previously was just the result of the car having sat in the sun for a while. Searching through the heater related posts in this forum there are quite a few about no heat, none so far on this issue.

 

On Saturday it was moderately warm (mid 70s) and sunny when we drove to a store about 10 miles away. The car sat in the sun there for roughly 30 minutes. Start it up and start to drive home and it is blowing hot air again. No thermometer with us but it was probably around 85F. Circulation is on vent (not recirc) temp set below ambient, A/C off. This time I just opened the back seat windows, left the climate control as it was, and kept driving. After roughly 10 minutes the air coming out of the vents finally dropped to ambient temperature (5 minutes on surface streets, then 5 more on the highway). Of course the car was in full sun during that drive too. So either the heat somehow sticks on for a while when the car is cold or something in the air path gets really hot when the car is in the sun and it takes a considerable amount of air passing through it to cool it off.