A/C modified: ETR-switch from Maytag
 

I'm using the MB service manual terminology, instead of WorldPac, to descibe a substitute for the ETR-switch on 123 and early 126(81-85). The one that disconnects the compressor when the evaporator nears freezing.

The problem with many ETR is that it's set way too high thru over-caution by MB or just old age on our cars; 38ºF is not uncommon. While I was adjusting my ETR (which is a pain to do) I noticed the similarity of the RANCO (a major manufacturer in controls) ETR from Mercedes with the General Electric thermostat I'd just replaced in my refrigerator.

Pic #1. Ranco ETR from Mercedes (difficult to adjust, done by very few)
Pic#2. My refrigerator
Pic#3. General Electric ADJUSTABLE thermostat (ne. ETR ;) )
Pic#4 After testing in ice water and set for 32º wired in for test runs.
Pic #5 Industrial strength ETR :eek:

Bruce, that's a terrific solution. The SD never gets its vent temps down very far and I'm sure the evap temp switch is the culprit.

Any recommendation on where to buy such a switch and p/n?

Try these people http://corporate.johnstonesupply.com/.

The one in my area has gotten me out of a tight spot many times, plus they have a awesome catalog.

Brian,
ANY appliance parts place will have 'em... most common repair part sold for refrigerators. Shop price, they're all the same. Obviously, every dead refrigerator/freezer has one waiting to be put to use in an MB ;). if the "bandwidth" of temperatures covered by the knob adjustment is not in range, that's easily adjusted by a screw. I paid ~ $12 for mine.

Edit: Might have to look around for that $12 deal.....:rolleyes: , But here's an online parts place; and brick and mortar, of course, will have them.
http://www.partselect.com/xq/aspx/Inventory.105315/qx/PartDetail.htm?SourceCode=8

Thanks.......I'll keep an eye out for a trashed fridge.......damn.......I trashed one myself about six months ago.......:eek:

This was my solution.http://www.oldairproducts.com/shop/product_info.php?products_id=3819&osCsid=aaa2204f4e80ea6a939847dc9f206a66 The thermo stat has a 48" capillary so you can mount the switch/temp selector where its convinent,been using it for the last two months.These guys were very helpful,Johnny

Johnny,

Great find. I had looked at street rod engine electric fan controllers, which, of course, are essentially the same but a different temperature band. But, I hadn't found (or thought of) the street rod type airco controllers AND you did it two months ago. :)

Anyone who drives a '38 International has to be thinking ahead. ;)

Or someone who threw in the towel trying to get his 85 300sd climate control to come back to life.This still gives you temp control ,and I wired it so the low pressure cutout is still installed for protection,these folks at Old Air have a high temp/low press switch built into one.Thanks for noticing the International,Its pretty Much a Chevrolet S10 Chassis with a Vortech V6 just using the International Body.Johnny:)

Test drive showed that I'm set a bit TOOOO sensitive. Cycles as soon as the evap gets to 32º, so it's on/off, on/off. Need to get it to work only on icing. Some adjustments and I'll try 'er again.

What kind of vent temps are you seeing? Would someone mind explaining how to adjust the ETR? I did a search but most threads concerning the ETR were discussing its location.

Yep, that problem is likely to continue. The allowable cycling range of a refrigerator is probably 2° or so. The evap will climb 2° within about 15 seconds of the loss of new, cold fluid, especially with the fan running.

Can you adjust the range to a larger value on such a switch?