Help Needed Diagnose Climate Control

[reidcc]

Hi y'all-

2000 'lara SLE- bought end of March this year. I noticed then- that heat would take a dive after about 20-30 minutes of driving. Car would warm up and I 'd get great heat. After the 20 or 30 minutes- I would need to now turn up temp from 72 to about 80 just to get warm air.

During Summer I'd have AC on in AM- and again- after 20 minutes or so of driving- it would seem to go completely cold- and to get ANY warmer air- I'd have to jack the control to 78 to 80. It seems like a mix issue and maybe a blend door is stuck at cold.

Now that fall is hear its getting cold again, and sure enough- my heat is playing the same games. I'd have great heat- but then after the 20 or so minutes-- it would go cool and I'd ned to jack the temp. All of the above scenarios are with the AUTO button OFF. With the heat issue- it is with AC off. Earlier in year I found the diagnostic to checkout sensor issues by holding two button and powering on- and back then- I had no codes. Last week I ran the test again- and I had a Code 21- meaning Solar Sensor.

During this past week- while driving over two hours with it- I tried the split mode setting(Feet and Defrost or Feet and Vent)- and I had warm air out the Feet vents and cool air coming out the upper vents.

Does a Code 21 make sense for all these issues= or is it masking something else? Has anyone replaced one- easy to replace yourself?

Thx
Chris

[reidcc]

Wow-

34 views- and no clues<g>...
OK- I have replaced the right side solar sensor twice with recently wrecked solara units. Both units still show Code 21 on the LCD front panel. Should I have cleared the original code 21 first?

My normal mode is to set it to 80 degrees for my commute- and live with it as I know it'll eventually go colder. For the first 20 to 25 minutes- I will get hot air out of any level output- whether it be floor, dash vent, or defrost vent.

Once the unit goes to a cooler temperature on its own- I notice it is definitely cooler from the dash vent and defroster than it is on the floor vent. Again- I do not have the AUTO button on, nor the AC button on, and it does not matter whether it is in recirculate or outside vent mode.

Is the LCD dash unit the actual controller- or is it just a dummy switch and readout? I will probably try replacing that next, or at least looking at the back of unit to make sure everything is connected properly.

Thx
Chris

[reidcc]

OK-

Another symptom... drove for 90 minutes highway speed. Again- heat came up real strong, and again after the 20 minutes it went to almost nothing, and then cool air. I tried the dash vents, and upped it a degree at a time after 80 degrees. Even at 85 degrees- it blew cold air, but the minute I turned it that final twitch to HOT- it cranked fully hot air.

There seems to be no modulation of heat up until the MAX- then I get full heat.

I need to go boneyard hunting Friday anyway- looking for a left headlamp. I'll try shotgunning it and try the Heat/AC Control Panel(LCD type) and go from there.

At this point- I have no resource to figure this out. The Service Manual does not have anything regarding Auto Temp Control.

Thx
Chris