Yes, its possible that the resistor has failed again. If you have a DVOM(digital volt/ohm meter), you can check the resistor yourself. It is located underneath the right side of the dash. Unplug the connector from the resistor, and then check the resistor itself. There should be resistance between each of the terminals on the resistor. If resistance is missing between any of them, then replace the resistor. If resistance is present between each of the terminals, then either the fan switch module is bad or a short/open in the wiring harness.
Is yours manual ac/heater controls, or automatic(digital controls)?
Ok, manual control has a cost to me of $244.95, when you figure in markup to be profitable, shop would charge between $310 and $350 for the part. Labor runs 2 - 2 1/2 hours. If shop charges say $80 per hour(which is national average, but each shop sets hourly labor rate according to their overhead costs), you would be looking at $160 - 200 labor.
So, low end, $470 parts and labor, and high end $550 parts and labor.
His estimate is within those margins
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