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Dash A/C, evaporator temp control switch


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Posted (edited)

Has anyone changed one of these switches?  It is the switch that shuts off the compressor clutch on the engine if the temperature at the evaporator gets to about 38 degrees so that the evaporator does not freeze over and restrict airflow.  It uses a 'bourdon' or 'capillary' tube to activate the switch.  Mine is not making the circuit anymore... A/C works great (too good.. freezes up) with the terminals of that switch jumpered....  I've been 'nursing' it along by manually switching between "A/C" and "vent".

Does the tube just pull out of the case? Is it attached inside or just sticking in there?  I have a new switch/tube coming and wonder how hard it is going to be to change.

old part number is A46-3211-000

2003 HR Endeavor... 

dash a_c temp sw.jpg

Edited by Cubflyer
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The tube is a permanent part of the switch assembly. The tube has to be pulled out of the evaporator and the tube on the new switch assembly inserted in its place.

The tube is filled with freon (or similar) at the factory and permanently sealed.  The fill fluid produces a pressure proportional to the temperature of the coldest part of the tube. The switch is actually a pressure switch that works off the pressure in the tube.

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Ken the probe is sometimes held by a small clip or just the friction of the cooling fins. It should be in contact with the cooling tube. The temperature of the coil also increases nearer the outlet so maybe you should place it in the original location and see how it performs. I bought one with an adjustable setpoint for $45 on Amazon.

 

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Thanks Gary,

I was wondering if I would need to open the "box" in order to replace the switch and properly place the end of the probe, or if I could just pull it out (without damaging the evaporator) and stick the new one in at about the same position.  I was afraid it was attached somehow or could not be placed properly by just sticking the new one into the original hole.  Being held with a clip or even just the fins and/or in contact with the cooling tube means to me that this is a project for after my current trip.

Any 'clues' to opening up the box/access to the evaporator coil?  It does not seem accessible from the front (where the tube comes out and the switch is mounted).  I have not looked on the dash side....

In Denver currently, getting the part Sunday, hitting the road Wednesday, so I guess I will just keep "manually" controlling the compressor..... beats not having any A/C.

Ken

I got brave today, gave the tube an aggressive pull and out it slid from the evaporator box.  Seems to just go in there straight about 6", does not seem to be attached at all.... So when the new switch arrives it should be an easy install....... I hope.... 

Ken

 

 

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