'87 DeVille. I'm pretty-sure I have a bad module. I tested the fan-outputs for voltage and each shows less than 6v. Neither fan runs, both are good, and power to the module is present. I'm trying to find a good used-module, #1641400, since I can not afford new. Is this voltage test correct to show the unit is bad? Thanks

Yes, your test is accurate. I've replaced that module before...To find a new one, I'd suggest a trip to the local junkyard, as they should be cheap and plentiful (around $40.)