Unfortunately, I don't have the amp or schematic for that one. I did have a Crown SA-2 which has the exact same fan. Once upon a time, I wanted to modify my SA-2 with a die cast boxer type fan. ....you know, to "make it quieter". The stock, strut type fan was already quiet. Low and behold, the boxer, more expensive, better looking fan was noisier. Talk about fixing a non problem. Anyway, I remember the strut type fan needed between 70 and 80 VAC to get started from a dead stop and about 50 to 60 volts to keep turning after it started. It was a long time ago, so my memory may not be the most accurate. Many 117 VAC will operate when a pair are series wired, leaving 117/2 VAC across each fan. In an electromechanical system when you've got to make a guess, go with mechanical faults. I believe that fan uses sintered bronze bearings. If you can get to the bearings, a good light bearing oil might free the bearings enough to let the low speed mode voltage turn the fan. If you can manually turn the fan, when on in quiet mode, with your finger (or pencil!!) and it continues to run, it might be worth investigating if there is a turn on "kick start" voltage that might be missing. As I say, I don't have the schematic, but the kick start approach might be used by Carver to get over the initial current hunger the fan requires to get rolling. Sorry this isn't much direct help, but more a collection of ideas. If worse comes to worse, the fan shouldn't be too expensive to replace, ......or the temperature monitoring circuit shouldn't be too hard to fix. Good luck
....spend money on good speakers!!