A/C Thermostat C&#111;ntrol Switch

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Topic: A/C Thermostat Control Switch
Posted: Jul/29/2020 at 11:38am

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.

tomj

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Posted: Jul/29/2020 at 11:54pm

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

jsejamx

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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.

304-dude

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Posted: Jul/31/2020 at 1:24pm

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

401MATCOUPE View Drop Down

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Posted: Jul/31/2020 at 3:04pm

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

304-dude

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Posted: Jul/31/2020 at 3:58pm

401MATCOUPE wrote:

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

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

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Posted: Jul/31/2020 at 10:13pm

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: Aug/01/2020 at 10:56am

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.

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Posted: Aug/01/2020 at 11:29am

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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