Defroster comes on in the morning - can't shut off - air recirculation switch clicks

[jbrianfoto]

Weird problem has started in Klaus (1987 300TD) - within the past 3 weeks. In the morning the defroster comes on at a medium speed (not the normal high hurricane speed) - after about 20-30 minutes of driving, the air recirculation switch starts to click on and off (in an irregular manor) and then eventually the fan shuts off and the blinking / clicking stops. Sometimes it will start again, usually when I stop at a light. AFter the heater shuts off I can use all of the temp and fan controls normally (they will not work prior to this episode). Happens every day, morning and afternoon.

Additionally - last week I was in slow traffic, in the rain, and I had the defroster on (to clear fog from my winshield) - and I had to blow my horn. When I did, the blower motor shut off - then restarted after I let off the horn.

My monowiper also is running slow.

The glow plug lamp only comes on 50% of the time.

Hmmmm - as I am typing this, I am starting to think I have an electrical problem (maybe the alternator)?

I have a brand new, big battery, car always starts quickly.

Any ideas out there? I did jsut search on the blinking air recirculation light, but the symptom was different (blinking in a regulair interval - and that it was associated with code testing).