there is a resistor on the fan motor that has gone bad, some models have a resistor unit mounted near the fan in case this happens.
It is a function of the "dew point" of the air at any given moment. If relative humidity is high, the dew point will also be high and the swamp cooler air will be relatively warm. If relative humidity is low, the dew point will also be low and the swamp cooler air will be relatively cold. A swamp cooler in Phx AZ will put out air about 30 degrees less than the outside air, and works more efficiently when the humidity outside is very low.
Why are you replacing the switch? If the fan works only on high speed, replace the fan resistor. There was a TSB for this.
The air blows against the perspiration, and it in turn cools the skin as it evaporates. When a liquid evaporates is cools. This is how a swamp cooler works.
Try replacing blower control switch or module.
it is usally a dry connection on the fan speed switch
Assuming it works normal with all other speeds, it could be,Bad blower motor speed switch,Bad connection to speed switch,Bad high speed relay,Dirty, plugged up cabin filter (if applicable).
The blower motor speed resistor is burned out.
Low speed (1-4) relay bad Switch bad Low speed motor winding bad
The heater blower motor speed resister is burned out.
If you are saying the blower motor only works on the high speed setting, then the problem is a bad HVAC Resistor Pack.
An oil cooler works the same as a radiator that cools coolant
A 3 way switch wired ---- , but works A 3 way switch wired not to code ---- , but works A 3 way switch wired not to code but it works