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I just bought an '85 Supra and i have noticed a clicking sound coming from behind the dash. It clicks every 10-15 seconds. I dosent happen all the time or i just tune it out i dont know. Is this a problem and how would i go about fixing it?
 

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If it is a thin "plastic or slightly metalic" clicking, then it might be your HVAC temp control. This is a common issue on the MKII's, but I do not know much about what causes it or the proper fix.

I am sure someone else here does know the answer.
 

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Yeah, I get that too. Definitely something behind the temperature control panel. It's annoying so I usually I just turn the whole thing to "off". My a/c doesn't have any freon left in it, and fixing the climate controls in my car is WAY down on the priotiry list right now.
 
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I have that same sound, if you will check its probably the a/c compressor cycling. Check by turning off the a/c (leave the fan running) the clicking should go away. Low freon will cause this problem.
 

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Actually, there are several relays behind the dash to control the automatic climate control. You'll probably notice that you don't hear the clicking when you have your temp control in either the max cold or max hot positions, only when it is between those two points.
I've also been trying to figure out how to get it to stop clicking, it can get a little annoying while sitting at a stoplight! I've wondered if it had this sound when the Supra was first sold new, as I think I'd be a bit weary of buying a car that clicks so much!
 

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i ave the same sound i think it has to do with the temp controle. when ever the sound shows up i just change the temp from one sedi to the other. its like its a switch that is supos to shut of the ac or heater like the car is saying ok its the right temp now tern off. well thats my 2 cens on it
 

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Happens to me also. I always leave the temp control on full hot. Funny thing is that mine does it even when the fan is set to off.

It has to be a malfunctioning sensor or relay somewhere in the system.

It is also way low on my list of things to do. My air compressor isnt even going back in the car when I get the engine done.
 

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Flyin' Hawaiian said:
I've wondered if it had this sound when the Supra was first sold new, as I think I'd be a bit weary of buying a car that clicks so much!
Actually, no they did not click when sold new. Not all MKII's click. My red car never has and the white car used to once in a while....notice I said Used to. This is a very old thread indeed and so far, none of us have figured out a sure shot reason and fix.

A few things I have noticed however, it does it more in daylight than at night. Will do it weither the system is on or off. 2 weeks after I recharged the AC and started using it again, the clicking has gone away. also, the car that has never clicked, still has the grey plastic cover over the solar sensor in the dash and the white car which does click is missing the plastic cover......I also agree that it seems to click more frequently in the middle of the temp scale than at one end or the other.....

Since I've had no radio in the white car since I bought it, one thing I can tell you for certain, when it is clicking the arm on the AC power amplifier is moving in and out in time with the click.

My trip to Oregon this week should tell me for sure if the car really has stopped clicking completely.

Leslie
 

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Try moving the temp. control lever slowly back and forth when you hear the clicking and see if that changes the behavior of the noise. If it does, give the potentiometer on the end of the temp. control lever a shot of electronic contact cleaner and see if that gets rid of the click. The auto A/C system has two potentiometers, a slide type pot. on the temp. control lever, and a rotary type pot. on the power servo. The two pots have a tendency to make poor contact after a few years and cleaning them up will generally restore them to like new condition. The pot. on the temp. control lever usually acts up more frequently than the pot. on the power servo though in general. If you can see the power servo stem move in time with the clicking then the DVV (dual vacuum valve) is what's making all the racket and spray cleaning the pot. on the temp. control lever will generally quiet things down.
Leslie, let me know if the DVV in your red car starts to misbehave and start clicking/chattering with the rebuilt dash control assembly that I repaired for you. That assembly should last you a great many years without fail. 8)
 

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wow, I cant believe this has been fixed! the first time I noticed it was the first night I got the car when I was waiting for the kind officer to write me a speeding tickit... I also found out the radar dectector that I found under the dash worked, but not well enough... heh.

anyhow... thanks the the soultion
 

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ah hah! I get it now! It's not several relays behind the dash, but it's just one! And because the potentiometer is dirty, the relay is flipping on and off because of the "dirty" connection at the pot! So by cleaning the pot, it should make a good connection again, which will fix the clicking relay as well as eliminate the occasional blast of cold air!
Obviously, my pot is okay at the very ends, but is probably dirty in the middle or possibly a little warped which keeps is from making contact properly. The things you can learn by checking into the forum regularly! I'm gettin' a can of contact cleaner tomorrow after work-will let y'all know how it goes...
Chris
 

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Yeah, I'm gonna give it a shot this weekend also.
All over the country, cans of spray electrical contact cleaner are flying off the shelves into the hands of invigorated Supra MKII owners.
I think I should start manufacturing the stuff myself, then I'll hit every message board on the web: "Hey I had that problem too on my (INSERT MESSAGE BOARD AUTO HERE). I gave it a good dose of KeithD's Magic Spray, and it cleared it right up. Remember not to be shy with the spraying, use a good can or two with each application."

:wink:
 

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man i have the same problem too i'm gonna try that if i get a chance to this weekend.
 

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The slide pot. is located on the end of the temp. control lever. You can get to it by removing the knobs and the plastic faceplate on the Auto A/C dash control. A flashlight will help you see the pot.. Attach one end of the plastic tube that comes with the can of contact cleaner to the nozzle on the can and insert the other end into the pot. on the temp. lever. Give the pot. one or two small shots of cleaner and then move the temp. lever side to side to clean the internal contacts. You don't want to spray the outside of the pot., just the inside.
A slide potentiometer, or slider as some techs. refer to them, is a variable resistor that functions by moving a sliding stem. A good example of such is the "sliders" on a mixing board used by recording studios, etc..
A rotary potentiometer is round shaped and varies resistance by turning a shaft that generally has some type of round knob. In the case of the MKII Auto A/C system, the temp. control pot. sends a signal to the input stage of the A/C amplifier, which in turn controls the two tiny solenoids inside the DVV. The rotary pot. is connected to the stem on the power servo and provides a feedback signal to the A/C amp. which lets the A/C amp. know the position of the power servo stem. The whole system works in a closed loop fashion so any poor contact in either of the two pots. will cause the input/output signal voltages of the A/C amp. to become erratic and cause the A/C amp. to switch the DVV On and Off in a less than desirable fashion, thus the very annoying clicking that you hear from the DVV.
 

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I have the same problem....just tun up the music 8)
 

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The DVV vacuum relay is making the noise. It's a dual vacuum with magnetic relays. Located just above the radio, far left corner.

DaveA is correct. Try cleaning it.

If it doesn't fix it, try slightly pushing in on the temp lever
to see if it shuts up the clicking. Then the sliding pot is just
plain worn out.

I have two from parts cars. I used a VOM to test the resistance
between the two. One worked fine, the other was shorting.

Upon inspection, the malfunctioning one was just worn out.
 

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I want to add freon to my 85mkii. It got 3 valves, 2 on the compressor and 1 is behind the afm. Would someone please tell me which one is the right one to use?
thanks!
 

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The port closest to the engine block on the compressor is the low side (suction) as is the port near the AFM. You'll want to top off your A/C using one of those 2 ports.
 
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