AC Thermostatic Switch - 77
 

Guys, is the capillary tube supposed to be measuring the temp of the lower evaporator line? Thanks

I think so. The coldest point will be immediately after the orifice tube, which is that lower line. Theory-wise, it keeps any part of the evap above 32 degrees, and avoids icing the evap. If it was on the evap outlet it would regulate the closed loop system so that the inlet would have to be <32 degrees with load on the system. So yes, lower tube sensing (evap inlet) would be how I would design a system with a thermal probe. I can't remember exactly, tho - it has been at least a decade since I pulled apart a 77 evap box. I got out of the 2nd gen game in 07.

I was under the impression it should be on the line immediately exiting the evap core? And that's where the sticky tape is, with no cap tube, so why even put it there?

Looks like someone used ducting putty to put it there.

Check the service manual, that should make it clear.

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Attached is a pic of a 1977 evap box I found at Firebird Central. It shows the thermal probe globbed onto the lower tube (evap inlet). It looks like the OP's pic, so I think you have it correct. Makes sense to me - I would put the probe there if I was designing the system.

Interesting, learn something every day!

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Thanks for validating! I am replacing that switch today.

Fixed. I replaced the thermostatic cycling switch and no more short cycling. I was surprised to see two hose clamps holding it on. Four Seasons 35720 System Mounted Preset Cycling Temperature Switch.