Missing high and low GM AC fan speeds?

[JustJohn]

Hoping someone can point me in the right direction for trouble shooting - I panic every time something involves getting into the car's electric.

My fan switch, a 69 Impala, 4 position (I think) works in every position but the lowest and the highest. So I get med and med-high. I just replaced all the climate switches as part of a dash R&R but the condition was the same before and after.

Can anyone suggest where I should start looking? I think that only leaves me the fan resistor unit and wiring???

[H2Ogbodies]

Likely a faulty blower resistor-its common, and given the vehicle age that's where I'd look.

[JustJohn]

Likely a faulty blower resistor-its common, and given the vehicle age that's where I'd look.

So basically check resistance across the terminals on the resistor and see if I get the factory values? Pretty sure they are listed on my wiring diagram.

[astroracer]

No need to check anything, that is what it will be. These generally are only available through a dealer. Better call and see if they are still available for the old girl...
Mark

[H2Ogbodies]

You may just need to pull it out inspect it. Sometimes, they warp from the current heat and can deform enough for the coils to touch each other which can add to the resistance-make sure each coil is separated from each other.