A/C Thermostat Control Switch
Printed From: TheAMCForum.com
Category: The Garage
Forum Name: Electrical - non engine
Forum Description: Charging systems, lights, non-ignition system, it goes here.
URL: https://theamcforum.com/forum/forum_posts.asp?TID=106907
Printed Date: Apr/16/2024 at 10:01am
Software Version: Web Wiz Forums 12.03 - http://www.webwizforums.com
Topic: A/C Thermostat Control Switch
Posted By: jsejamx
Subject: A/C Thermostat Control Switch
Date Posted: Jul/29/2020 at 11:38am
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I have an A/C thermostat control switch for a 70 AMX. It looks like the copper tube might have been cut off on the end but its hard to tell. It definitely isn't soldered closed (was it originally?). If it was cut will it still function as there appears to be a fairly long length of tube left? Thanks for any guidance. |
Replies:
Posted By: tomj
Date Posted: Jul/29/2020 at 11:54pm
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It's irretrievably deceased. It was filled with a pressurized gas. Buy an udder! lol ------------- 1960 Rambler Super two-door wagon, OHV auto 1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
Posted By: jsejamx
Date Posted: Jul/31/2020 at 1:07pm
| Yea, that's what I was afraid was the case. Does anybody know what the 4 seasons replacement part number is for a 70 AMX? I can't seem to find a reference for a 70. The one I have here has Ranco a30-3010 on it but I can't tell if it is an OEM switch or not. I has 2 terminals AND a third wire on the back of the switch. All the AMC replacements I see (Rebel, Hornet Ambo, etc) have only 2 terminal lugs on the back of the switch. Appreciate any assistance. |
Posted By: 304-dude
Date Posted: Jul/31/2020 at 1:24pm
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I don't see how it could be any different than a 70 to 72 Ranco switch. The operation has been pretty much the same for all cars. Unless the 70 has a ground wire. Depending on how it is mounted. Though pictures may show the tube looking like a wire. I can look around for my switch to see if it has a wire and two prongs. It's off a late 71. ------------- 71 Javelin SST body 390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
Posted By: 401MATCOUPE
Date Posted: Jul/31/2020 at 3:04pm
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To my knowledge there was never an aftermarket switch ever offered and it that tube is cut.....all comments are correct the tube is not repairable....don't toss it though, I have seen other parts of that switch fail, it might be good for detail parts. 68-70 Javelin and AMX with air conditioning used the same switch, round knob/rotary switch , 71-74 AMX Javelin switch is completely different....this uses a sliding switch ------------- Ross K. Peterson 68X,GoPac,343,AT,52A(1stCar) 68X,GoPac,390,4sp,52A 69X,GoPac,390,4sp,64A 70X,GoPac,390,4sp,87A,8 70X,GoPac,390,4sp,BBO,8 70 Jav SST,390,AT,BSO 74MatX,401,AT,Prototype 74MatX,401,AT |
Posted By: 304-dude
Date Posted: Jul/31/2020 at 3:58pm
I was thinking other cars, not just Javelin. As to find a good donor, instead of limiting to a year or body. I was thinking of just how the wire would come in place on such a switch. Technically 70 and 71 are much the same outside of the switch operation at a mechanical stand point. Should be able to verify the wiring on mine, just to satisfy my curiosity. I know the weather eye has a light bulb fixture, but that should be easy to spot as not part of the switch itself. ------------- 71 Javelin SST body 390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
401MATCOUPE wrote:Posted By: jsejamx
Date Posted: Jul/31/2020 at 10:13pm
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This is a funky looking switch. I don't know how to post pics so I'll try to describe it better. There is an insulator board attached about a 1/2 inch away from the front of the switch body (toward the knob) which has 3 rivets in it. A copper strap connects 2 of the rivets on the front side. In the space between the insulator board and the switch body there is a round copper ring, another round insulator piece, and a compression spring which pushes the ring into contact with the rivets. The knob shaft goes through all this stuff but none of this turns when you turn the switch. On the back of the switch are 2 side by side terminal spades marked 1 and 2. Below that is another terminal spade marked 3. There is a short blue wire with one end attached to spade 3 and the other end attached to one of the rivets with the strap on the insulator board. A second short blue wire is attached to another rivet (not the other one attached to the strap) which has a pig tail termination. Is this isome type of ground configuration? I looked at a couple of parts interchange references and they say that a Ranco #35845 in the interchange switch for a '70 Rebel, Ambo, Hornet, and Gremlin. There is no reference for either a Jav or AMX. The only pictures I can find (and they may be generic pics) shows just 2 terminals on the back side of the switch and none of the insulator board stuff. I'm wondering if I can take this one apart and then get a 35845 switch and swap out the sealed tube and portion as that part looks the same in the pics. Unfortunately I don't know if this is the OEM switch or already a replacement and if so is it the correct one.
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Posted By: jsejamx
Date Posted: Aug/01/2020 at 10:56am
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New Development. I forgot I had parted out a 70 Javelin shell about 15 years ago which had a dash in it. As it turns out it was an A/C car and it has the exact same switch in it. Also, I can tell the first one has a cut tube. All the insulator board stuff is a grounding loop of some sort. If I slip a few pieces of index card between the copper ring I previously described and the rivets, I lose continuity between the short blue wire attached to the switch and the short blue pig tail wire. Next I put them both in the sun for about 15 minutes and checked the continuity across spade 1 and spade 2. The uncut one it had continuity but the cut one didn't. I'm now convinced I want to Frankenstein the one that is no good with parts from a new switch as I think these are original switches. Does anybody know what the "off" temp should be for this setup? I'm thinking I could put the thermocouple end in some dry ice (if needed to go that low) and then test to see if they both open, assuming I get that far with repairing the other one. |
Posted By: Heavy 488
Date Posted: Aug/01/2020 at 11:29am
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Its not controlling a deep freezer. Besides from letting you set a comfortable temp, it also keeps the coils from freezing solid from humidity and condensation. Unless the switch is set to a desert override position, the normal range bottom end is about 34 or 35 degrees F. The capillary tube is reading coil temp.
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Posted By: jsejamx
Date Posted: Aug/01/2020 at 1:49pm
| Thanks, that's what I was looking for. I'll try regular ice first although that is only 32 F. Was thinking about dry ice as that is the next lowest temp solid and is readily available, at least near me. |
Posted By: tomj
Date Posted: Aug/01/2020 at 11:59pm
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I wouldn't worry about exact calibration, a go/no-go test with ice should be sufficient. What Heavy sez. If you can make the switch open/close with ice it's working. ------------- 1960 Rambler Super two-door wagon, OHV auto 1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
Posted By: george w
Date Posted: Aug/02/2020 at 6:22am
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I believe the disc you're referring to is actually a rotary on/off switch. When the control knob is fully CCW it disconnects the power from the switch, otherwise the rotary temperature controlled thermal switch would always have power going to it. This means depending on ambient temperature the compressor clutch could engage and the blower would be running at low speed all the time the ignition switch is on. There should be a little "calibration" type set screw on the body of the thermal switch. This screw will allow you to tweak the temperature of the on/off point for the compressor. Normally you don't need to mess with this but if you find the temperature control knob's operating range does not seem to be "centered" then you can adjust this set screw to alter the on/off trip point. ------------- Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new. |
Posted By: jsejamx
Date Posted: Aug/02/2020 at 7:19am
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Nothing in the area of the disc or the disk itself rotates as you turn the shaft. I can see the cam plate which moves the lever on the switch as you rotate the knob (the rotary switch portion) and its not part of this stuff.The insulator board, copper ring, compression spring, etc. all have clearance for the threaded tube which attaches the switch to the Weather Eye bezel. The insulator board itself is riveted to the switch body. I looked at the wiring harness for the A/C and there is a 2 spade connector and a male pig tail that go to this switch. It all looks original (no splices) so I'm pretty sure this is the OEM switch. I'm going to try to find the harness diagram to determine if it's a ground or not. |
Posted By: george w
Date Posted: Aug/02/2020 at 8:07am
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It's been a long time since I've been under my dash but I believe either that disc is supposed to turn or there's a moveable contact that moves around that disc. There should be an OFF detent felt as the shaft is rotated fully CCW. When fully CCW there should be no power going to the thermostatic switch ( which cycles the compressor ) or out of the short pigtail that goes to the blower speed switch. That pigtail wire is not a ground. It feeds battery power to the low speed side of the blower control switch to automatically activate the lowest speed of the blower motor as soon as the a/c system temp control is moved off the OFF detent. ------------- Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new. |
Posted By: jsejamx
Date Posted: Aug/02/2020 at 11:50am
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George W. Thanks for the explanation , it works exactly as you mentioned and helped me locate the problem. The rivets which hold the insulator board to the switch body pulled out about a 1/16 of an inch. The compression spring pushed the whole thing forward which disengaged the ring from the short flat on the shaft. I pulled the board off, removed the rivets, re-oriented things and then squeezed it back together and sure enough the ring does turn when you turn the knob. Not much design margin there! Anyway, thanks again. Onward to trying to fix the other problem.
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Posted By: george w
Date Posted: Aug/02/2020 at 6:56pm
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With old cars it's always something ! Glad to be of help. ------------- Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new. |