First I want to thank everyone who has offered advice so far about my problem it has helped calm my nerves...somewhat. I have a '99 E55 which had a problem with the blower motor running just fine on all speeds for about 3-4 minutes after crank up but would drop to a low speed after that, even when the Control is on Max (on auto or manual). All indications pointed to the regulator being bad so I got a new behr regulator. Needless to say this didn't work so I thought per chance I had gotten a bad regulator..So I got another and it does the same thing...I am lost....This is what I have checked..New Air filters..4 blower regulators(2 new) and all act the same. Ran the Codes on the Control head for the fan speed and they read what seems to be the correct voltage when the fan is working right and not. Also checked the true voltage on the yellow trigger wire to the regulator during the entire cycle. All voltages seem to be ok. This is what I checked today. I took the motor completely out and checked its operation. It seemed to spin freely and while it was installed I checked the amperage pull with a clamp and it was about 10 amps so I don't really suspect it. I put the key in the on position (car not running) and measured the regulator voltages...The fan ran on high speed for a good 15-20 minutes and worked normal...The Large red wire read 11.7V, the small red wire 11.7V, and the trigger wire (yellow) read 5.6-5.7V, the entire time. When I started the car the blower ran it's usual 2-3 minutes and then dropped to what could be decribed as a #3 setting. The voltages were as follows after that happened...Large red wire 14.1V, small red wire 13.8V and the trigger wire 5.5V. When the fan drops out it sounds the same speed as when it is working correctly on the third setting, which under normal circumstances reads 1.5Volts at the regulator...How could this be? If the yellow wire controls the regulator and the voltage didn't drop but a tenth of a volt why did the blower slow so much? It seemed odd to me today that it ran for so long with the engine off but with the car running it quit as usual. I am not certain this happens all the time because I think I have checked it in the past with the key on only and the motor shut down then as well. Any help would be so greatly appreciated..My wife and I are suppose to be going to Gatlinburg for the Big Rod Run this weekend and she said I would have to fan her the whole way if I didn't get it fixed. If I am on the right track...The control unit seems to be doing its job, I don't notice any voltage fluctuations that would say it is causing the drop in speed. And surely out of 3 regulators one would work. The regulator back gets hot enough to fry an egg (or finger) on which I would think is normal perhaps...So perhaps the motor is placing to large a load on the regulator and I am missing something...All I can say is HELLLPPPPP!