It it aint one thing its another

[Harmon]

Fixed Fuel Guage...happy

Put truck back together (new dash...replaced dash lights)

Hooked up AC with R-134-A

Blows cold, but seems to only blow in 3 positions... I thought there were 4 positions for blower with HI being the 4th one. 

I replaced Hi blower relay and checked ground to cowl above blower moter----still only 3 posistions of blowing.

I checked 20 amp fuse in fuse block under dash and it is fine.

Im in Texas...I need that Hi side...any idea of what to do next?

[TexasRed]

switch is still good?

[Harmon]

switch meaning the one in the dash?

[TexasRed]

yep.

[Harmon]

I think thats the problem....thanks.

I have to push up really hard to the HI posistion in order for the hi side to kick on.

Thanks!

[Harmon]

Is it possible to just by the switch and replace it for the blower levels?

[TexasRed]

Maybe. . . .http://www.autozone.com/autozone/parts/Duralast-Blower-Motor-Resistor/1977-Chevrolet-K10-1-2-ton-P-U-4WD/_/N-incirZ91tag?counter=1&itemIdentifier=239268_0_3319_5281

[DnStClr]

Maybe the switch is binding up. There are a number of wires attached to it so take note of their location. You have to remove the instrument bezel to work on it or replace it.