Carrier Supra 850

[foodco]

Hi all,

Having a problem with a carrier 850. The evap fans run at a very low speed when the unit is operating. If I disconnect three of them, one spins as fast as it should. Start reconnecting them one by one and they all run slower and slower. So, it would appear to be a power (electrical) issue, ie, not enough power is being fed through to keep them all going properly. The problem happened all of a sudden, no build up or warning. I am thinking the generator (slung under the electric motor and driven by the alt belt) is not working properly (down a phase) but before I buy another at considerable expense, I thought I might ask the opinion of the experts here and if any of you had experienced the same. I have checked all the electric fan motors on the evap, they are now fine, one was replaced as it gave a heavy electrical buzzing on start up.
Thanks in advance

[foodco]

Does anybody here have any ideas?
Help would be appreciated.
Thanks