Chrysler Repair: Resistor Block for A/C & Heat Fan Switch, amp fuse, dodge caravan

Question
Hello,
  Even though I'm asking about a 2002 Dodge Caravan and it is outside you range of vehicles, I thought I'd ask this question. Our van has a resistor block for the various fan speeds for our Heat and A/C fan. In this block there is a diode that is rated for 10 amps (book states that the fuse is 20 amps). Our problem is the diode keeps going bad even though the fan sounds fine and runs fine on high speed. When the diode goes bad the only speed that works is high. I do work in a factory maintenace department and am familar with motors and amperage draws. I contacted a local dealer and they said they did not have any specifications for the fan motor amperage draw. I could replace the diode if I could find one. With all this in mind, do you have any ideas or suggestions?
Thank you for any info you can give me,
Jeff

Answer
Hi Jeff,
I don't have any manuals from that recent a vintage, but I notice that the blower motor in vans from years up thru '98 had fuses of 40 amps but the bloc didn't appear to have the diode in those years. However I see a component that was present in the blower motor bloc for '96 Cirrus/Stratus manual and is called a "thermal limiter" with no spec given or even a symbol but I suspect it is a diode. That circuit had a 30 amp fuse. Maybe you can find an entire bloc from a wreck? It might have to be a 2000 or a 2001 before you get the bloc with the diode. It does appear that a 10 amp diode might not be sufficient based on these earlier blower circuits.
Roland