I haven't seen a complete description in any service literature of just how the solar sensor works, but this is how I think it works and why. Maybe others can elaborate on this!! The solar sensor is a photoresistor that changes resistance when exposed to light and is connected to the input stage of the A/C amplifier. The round, tinted plastic cap that snaps on top of the sensor is a light filter that is there to calibrate the solar sensor to the auto A/C system, basically by controlling how much light intensity is required to produce the proper output voltage signal from the solar sensor during daylight. The auto A/C system uses the solar sensor to sense how much radiant heat from sunlight is coming through the windshield and heating up the interior of the car while sitting in a parking lot, driveway, etc.. You've all probably noticed that if you get into your car after it's been sitting for awhile in the sun and the interior is scorching hot that turning on the blower switch to "Auto" immediately causes the blower to run at full speed for a period of time regardless of the temp. control setting. This is done to help purge the interior of stagnant hot air and to help cool down the interior before the in-car and ambient temp. sensors take over and sample the interior and exterior air temp.. "I think" the solar sensor is responsible for this function of the auto A/C system but I haven't had the opportunity to experiment with this part of the system yet. The infamous clicking of the DVV is usually caused by the potentiometer on the temp. control lever making poor contact, but probably any erractic input signal to the A/C amplifier can cause the DVV to click. Based on the schematic diagram of the A/C amplifier in the TSRM, I suspect that any noise or erratic signal voltages seen on any of the sensor input signals to the A/C amplifier could cause the DVV to click. If the solar filter is missing on top of the solar sensor, one would think that would cause the solar sensor to be more sensitive to light and thus respond to a lower light intensity and thereby cause the voltage signal output of the solar sensor to be way out of range, possibly overloading the solar sensor input on the A/C amplifier. All of this is just pure speculation on my part, but this is the best that I've been able to figure out about the functionality of the solar sensor in the auto A/C system. Whew!! Sorry for the long winded reply! :?
. I'm sort of in the middle of restoring (that is cleaning, patching, and repainting) the interrior, so I don't have everything back together yet. I focused on getting it driveable again. I'll put it back on tomorrow and play around with it for awhile to see what happens.
