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Discussion Starter #1
Why does the AC system need to know if the sun is shining? Does it alter its cooling power based on light? What if I park under a street light on a hot night, makes you wonder if I'm not getting DAYTIME power, Hmmmm.

Also is the plastic sensor cover important, the one on my blue dash broke off and the replacements I have are red, and red.

???
 

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I read elsewhere that if the solar sensor is damaged you will get that annoying clicking sound behind the dash and steering wheel. I've driven my car for years wondering what the hell that noise is, knowing it was somehow related to the heat/cool system and it even still did it after the a/c quit working. It'll probably still do it after the new 6m goes in it next week.
 

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Well, I never reconnected mine after I put my dash back on a week ago, and haven't had any problems yet... so I guess I'll experiement for the group on this and get back to you with the long-term results
 

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Right on, that'll be one of the first things I'll mess with when I get mine back on the road, hopefully next week!
 

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Yes, the system DOES care if the sun is shining or not. Unfortunately, it's sort of one of the little bugs in the Toyota AUTOMATIC A/C system, vs. the "normal" A/C system that was optional on the 82 - 85 RA Celica's (the Celica's did not have the Auto A/C system). Basically, just one little thing that gets all bent out of shape can be enough to throw the "Auto" system into a tizzy.

Parking under a streetlight will not make any change, the sensor is looking for "AMBIENT" light, which basically means that it's looking at the entire big picture!!!! Not just this small amount of light coming from a street light. Plus once you move the car away from the streetlight & it goes dark..... :shock:
 

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so is it confirmed that the clicking noise is because of the solar sensor? or has anyone tested this. I'd like to know before I get mine recharged and stuff, starting to get hot around here.
 

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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! :?
 

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I can attest to the fact that a missing cap on the solar sensor leads to some clicking.
I never used to have any clicking in my white 83. Last year the cap somehow disappeared (not sure how that happened).
Since then, when I pull my car out of the garage on a sunny day, the clicking starts. If I put a piece of paper over the solar sensor, the clicking stops immediately.
When I pull my car out at night there is no clicking.
 

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Discussion Starter #10
ok then

Well I'm putting a new AC compressor in this week and for the past few weeks I have been going over the entire AC system because I WANT IT TO WORK, I have not had AC in a car I own for 7 years, so the solar sensor is the one thing I could not figure out, I'll put a new cap on it prior the charging the system...Thanks for the detailed speculation, your thinking went a little further then mine, so thanks again.

The clicking behind the climate control center was discussed in detail in another thread.....something about dirty contacts...

thanks again
 

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Discussion Starter #11
Dumb

Dumb question.....What is the TSRM, all I have is the Haynes book....where can I get the TSRM??
 

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Toyota Shop Repair Manual, or Factory Shop Repair Manual is more common (FSRM). Why from Toyota of course.
 

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Discussion Starter #13
AH

Ah......but of course.
 

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Re: Dumb

Angkistrodon said:
Dumb question.....What is the TSRM, all I have is the Haynes book....where can I get the TSRM??
What year TSRM do you need? Some people may have spares. :lol:

Leslie
 

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Discussion Starter #15
1985

In need one for a 1985 MKII.....Please
 

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I saw someone post about how if this sensor is damaged it will cause a clicking noise in the dash? Is this so? I have a clicking noise in my dash, when I turn the fans off and then back on again it will stop temporarily and then start again. Dones anyone know anything about this or how to fix it? THANKS!
 

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ok, time for a one month repot (give or take). I think the clicking may be related, because now the car clicks at night sometimes (I'm working the a$$-early freight shift at UPS right now, so I'm on the road at 3:00am). It had been clicking before for about a year, so this is nothing new, but I don't remember clicking at night. Of course, it doesn't always do this... :roll:
Other then the clicking, I have yet to notice any real ill effects. Of course, there could just be something I haven't noticed yet, so I'll try to keep all of you posted.
 

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Tell you when I reinstall my climate control panel :) . 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.
 

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Moving the heat or vent selector stops the clicking (it is the typical Mk II click from behind the climate control panel). Its just odd that it happens at night (though I might just not remember it being at night; anyone else have clicking at night?). Otherwise, no change
 
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