When you say no heat, do you mean the blower motor is not running?

If so, there is more than a resistor by the motor, and it's not cheap.

I had the blower stop working on my '90. I took the motor out and the shaft would barely turn it was so tight.

I put some oil on the shaft and turned it a bit by hand to loosen it up. It worked perfectly after that and has for the last seven years now.

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2012 E350
2006 Callaway SC560