I did a search and cound't come up with any clear answers to my typical blower motor problems..

it hasn't been working for a while. could be a problem in the winter with defrosting the windshield so i start to work on it today.

1. check fuse #11. looks fine.

2. took out the blower motor. hooked it up directly to battery and it ran. so i ruled out the brushes.

3. plug it back in and let it hang down while i try to put the fan on. the fan kicked on. stayed for a couple of seconds and turned back off. i then pushed all the buttons and turned up/down the temp setting. it kicked on and off at random intervals for a while. then it stopped that.

4. I thought it was the HVAC controller. and think it might need to be resoldered.

5. before i took it apart i pushed it a couple more times and i notice everytime i push anything but "o" (off) there is a humming/ringing behind the dash.

seeing from number 5 i was thinking the controls do work, but maybe there is another component at failure causing to power to the motors? any input would be appreciated.

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198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05