AC Fan Switch Ground

I think the relay mod that PCB did is the best solution. It keeps any current from going through the switch and thus keeps any arcing etc away and the relay is more than capable if handling any current etc. Being the type of person I am I like to find the root cause if an issue.

Does anybody know if the behavior of the compressor changes based on the fan switch position?
 
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protege5
no. the compressor behavior is controlled by pressure. it is not variable, it's either on, or off. fan speed just changes the amount of air flow across the evaporator. AC will actually blow a few degrees colder in position 1 vs. position 4 because the airflow is reduced, and the air is more "saturated" by the cold for lack of a better term. But compressor operation itself is either on or off.

The only way fan speed MAY have a SLIGHT impact on compressor operation is just cycling because as the evaporator changes the refrigerant back to a gas, the increased airflow could speed that up slightly causing the pressures to vary some, so that could cause the compressor to be on more frequently or for longer periods of time but that's really grasping at straws.
 

pcb

The Diagram Dude
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2002 MP5
I think the relay mod that PCB did is the best solution. It keeps any current from going through the switch and thus keeps any arcing etc away and the relay is more than capable if handling any current etc. Being the type of person I am I like to find the root cause if an issue.

I think the root cause is the switch. The wires in the connector were burnt and crispy for about two inches from the switch then the wires were OK.
That suggests to me that the heat was in the switch and conducting along the wire.

Here's a diagram that I made of my relays.. It might help you build one.





 
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