A/C Control
05-17-2004, 04:50 PM
#4
Racer
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Re: A/C Control (hunt4cleanair)
75 roll dails nothing happens, but I do hear the door open so that kinda tells me it's electrial I rebuilt the dails and changed the horizonal point style switch on the drivers side, but not the switch that spades point down. Previous
owner had installed two toggle style switches to control comp. and something else involed with the fan I'm going to go out and start checking power points. the something else is a control which I hooked up to those vertical spades. any ideas :(
owner had installed two toggle style switches to control comp. and something else involed with the fan I'm going to go out and start checking power points. the something else is a control which I hooked up to those vertical spades. any ideas :(
05-17-2004, 06:42 PM
#5
Safety Car
Re: A/C Control (jeaux)
I have a '75 control in front of me. 2 micro switches control the compressor and turn off power to the blower relay in the off position. Most of the functions are controlled by vacuum (defrost, heater valve, fresh air door, etc...). The micro switches are easy to check for continuity, but the control needs to be up where you can test it. The vacuum control tends to leak after many years because the light grease (looks like vaseline to me) dries out and makes a flakey, powdery mess that prevents a good seal. I've had great success carefully spreading the two halves a bit (not too much or the spring clip will be damaged) with a NEW single edge razor blade, then with the vacuum hose assembly unplugged I spray contact cleaner in to flush out all the crud. Blow dry with air (those air-in-a-can things for computer keyboards work well) and brush in clean light grease and they work like new again.
You can here the vacuum leak quite plainly with the engine running if it has one. It will be worse in some positions than others and prevents all the doors from operating properly. Hope this helps.
Hans
You can here the vacuum leak quite plainly with the engine running if it has one. It will be worse in some positions than others and prevents all the doors from operating properly. Hope this helps.
Hans
05-17-2004, 07:31 PM
#6
Racer
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Re: A/C Control (Wrencher)
Ok, here's what I have now I have it working, but only when the right wheel is in off position blows cold but not a lot of volume. could that be the low blower switch? :skep:
05-18-2004, 06:46 PM
#8
Safety Car
Re: A/C Control (jeaux)
OK let's get this straight. Right hand wheel controls temp (hot/cold) only. It has no effect on the fan, only the blend door which is cable operated. The left wheel is the mode switch and shuts the blower OFF when it is all the way up/forward. pull it back 1 click to MAX A/C and it powers up the fan switch. At this point you can do anything you want with the blower speed (4 positions) except turn it all the way off. Also, the compressor is energized as you pull the wheel down two more positions (A/C and BILEVEL). Once you hit the VENT position the compressor is disengaged through the rest of the positions (HEAT and DEICE).
Sooo, don't worry about the right wheel for now. If you hear the fan run (I like to open the hood so I can work at both ends and really hear it) in any position, thats a good thing. If it turns off with the wheel all the way forward, even better because it means your first micro switch works.
Any other senario, reply now.
Assuming it works, now you can now look at your resistor and high blower relay, both mounted in the engine compartment on the evaporator housing.
The resistor is under the fender behind the coolant tank on mine, but the relay is between the case and the engine valve cover. Also, right below the resistor is an overheat switch (two wires - looks like a radio capacitor). Make sure it's all plugged in. Wiggle the plug on the relay if they are with the key in the run position and mode switch on (in any position). The relays go out all the time due to a really bad, high heat location. Take out the resistor and inspect the 3 coils. Are they intact? Replace if damaged. Check that the blower motor has a good ground. In fact I'd make a heavy gauge (12 or 10 ga.) ground just because until you solve all your problems. It also prevents amp drop in these junky systems.
Hans
Sooo, don't worry about the right wheel for now. If you hear the fan run (I like to open the hood so I can work at both ends and really hear it) in any position, thats a good thing. If it turns off with the wheel all the way forward, even better because it means your first micro switch works.
Any other senario, reply now.
Assuming it works, now you can now look at your resistor and high blower relay, both mounted in the engine compartment on the evaporator housing.
The resistor is under the fender behind the coolant tank on mine, but the relay is between the case and the engine valve cover. Also, right below the resistor is an overheat switch (two wires - looks like a radio capacitor). Make sure it's all plugged in. Wiggle the plug on the relay if they are with the key in the run position and mode switch on (in any position). The relays go out all the time due to a really bad, high heat location. Take out the resistor and inspect the 3 coils. Are they intact? Replace if damaged. Check that the blower motor has a good ground. In fact I'd make a heavy gauge (12 or 10 ga.) ground just because until you solve all your problems. It also prevents amp drop in these junky systems.
Hans
05-18-2004, 09:44 PM
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Re: A/C Control (Wrencher)
Allright, When the switch is in the off position [rotary dial left] all the way up off, A/C is energized blowing cold air when I bring it down to max it stops as if it's turned off :confused:
05-18-2004, 10:02 PM
#10
Safety Car
Re: A/C Control (jeaux)
Whoa, sounds like some creative wiring or bad switches! It's not too tough to get a look at the controls by lifting it upcarefully (with the console plate) far enough to see whats up. Your on the right track looking at the electrics. My favorite tool for this type of work is a test light. Basically a housing with a bulb in it that has a pointy metal probe on one end and a longish wire with a ground clip on the other (my apologies if I over-symplify). Ground the wire, turn the key on and start checking the wires at the various electrical connectors with the probe. Start at the primary micro switch at the front of the mode wheel and see whats up. It may be bad or bent. It's kind of a creative switch with a couple long ends with contacts on them and an over-center spring that closes them. Easy to wreck. Let me know what you find.
Hans
Hans
05-19-2004, 08:54 PM
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Racer
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Re: A/C Control (jeaux)
Here's where I'm at if anyone's intrested from bilevel up switch shows conductivity even in the off position,shouldn't I lose conductivity at off position? Ok now for the vertical points style switch,it shows conductivity at off position one of my diagrams calls this master switch. this seems to be backwards shouldn't switch show conductivity at max a/c and normal position? Now I'm confused any suggestions? :confused: :confused: