AC electromagnetic clutch

Have a 69 b body w/ AC and pushbutton climatecontrollers.

When any of the pushbuttons are pushed in (Max AC, AC, heat, defrost, and even the off button) the electromagnetic clutch engages. You can clearly hear the AC clutch engage when you turn the key on. It is only suppose to engage if the MAX AC or AC button are pushed in. Anyone know why mine is enagaging when any pushbutton, including the off button is pushed in? I can get the clutch not to engage by pulling the "off" button out.

Everything else with the heat/defrost/AC appears to work as expected.

Thanks in advance for any help.

Sounds like the dash switch is flaking out, that's where the power is switched. I have been know to use the switch to control a relay that handles the load, rather than the switch.

my newest acquision an 85 Ramcharger does that with the AC off, I can hear the compressor kick in randomly at times (or at least it sounds like the compressor & the eng is slowing down when it happens). Everything works fine as far as I can tell but I did block off the vacuum? valve in the heater core hose when it started leaking but I think that would certainly be unrelated as the vac valve normally would be blocking the coolant in the summer with the AC on.

Is this white plastic part that says replaces 3502126 the switch you are talking about?

anyone know where they are avaialble? i need to get this fixed this week.
from the picture it looks like it can be easily replaced by dropping out the controllers.


Thank you very much for any help.

anyone know a part number? 3502126 may be for later year c-body from what i found... I don't have a good source though to look up the number of the part I actually would need

3431020 is the original part number. That supersedes to 3895033. You can also use 3895790 which adds the feature of turning the compressor on when you push the defrost button.
The switch you have, 3502126 is for 1972-1973 C bodies without temperature controls.

According to my '69 parts manual the original # is/was 3431-020, same part for A,B, and most C bodies. I am sure this has been superceded several times.

So, it very well could show up as for a later C using that 3501 number.

They seem to be a pretty generic part, looks much the same as the one for my '85 D100, and same as the one in the 92-93 D150 spare control I have laying around.

I am sure you have noticed it, but it looks like the clip that holds the vacuum lines in place is askew, possibly shorting across some of those bare terminal ends?

SMOKED AGIN!

Rock auto has it as HS101, with is superceding at least 4 times, and around $51.

Local parts house should have it ... or get it.



2dr has it right.

Thanks for all the info.

Can anyone confirm that this heater switch IS what is causing the magnetic compressor clutch to engaged when heat/defrost, and off buttons are depressed, but not when all buttons are pulled out?

Rock auto actually odes not have it to order though. you don't see this till you click to buy... that means off to the parts store. with the parts stores around here I am lucky if they can track a part #, never mind actually tell me if the part may be the source of my problem.

Compressor cycles when deforst is on over 32 degrees.I cant remember the year feds mandated it.Im thinking late 60s.but not 100% sure.Rocky

Last chance. anyone willing to step forward and say that a dysfunctional heater AC switch (as pictured above) can cause an AC clutch to engage when push buttons beyond Max AC and AC are depressed (heat, defrost, and even when the off is depressed). only time the clutch is NOT engaged is when all buttons are not depressed...

Please help suppose to sell the car this saturday and need to get this fixed beforehand...

thanks

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Last chance. anyone willing to step forward and say...

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I say go to the parts store and get the darn switch.
After 45 years you need a new one anyway....