My heater blower is giving me grief. It still works but something is amiss. About 3 weeks ago it blew the strip fuse. Maybe just a coincidence who knows. I replaced that but now the fuse is holding fine but the motor seems goofed up. It blows OK for sometimes up to 30 minutes (sometimes much shorter) and then it will just slow down and go intermittant and then basically stop blowing. Sometimes this is accompanied with some resonanting sounds coming from the dash. (no squeeking though as I have read in other posts). The other piece of info here is it will not shut off when I turn the fan to the off position when the defrost button is pushed but does shut off when the next button is pushed (the up and down arrow heater button 2nd from the left of the buttons on the dash control). Maybe this is something different. This car has all kinds of wiring gremlins. However, there appears to be something clearly wrong with the blower motor as I can hear the rattling and resonating when it is shutting down and losing speed before it quits.

The question - is this simply a blower motor is shot or is there likely something else going on based on some of the other symptoms I mentioned. It does seem to work everyday from a cold start and then begins to baulk and shut down after some amount of time (5 min to 30 min). Thanks!

Even if it's not the Original Blower...
It Blew The Strip Fuse! Indirect Symptom-ology!
('Shark Bite on your leg, 'Good chance you were Swimming)

(Does the '93 have the Cabin Air Filters?)

Hopefully, what's going on is as the Blower is aging...
(and as it does the Brushes Wear,which requires more Amp OOmph, overstressing the ALMOST undersized wiring,raising the wiring's resistance,ad infinitum...AND if they are worn enough,Indirect connection,arcing.)
(The bushings [NO Bearings,that would eliminate a lot of these problems] may
be dry and need a drop or two of ATF,lack of which exacerbates the Resistance problems)

Hopefully,what's not going on:
Is a "Traveling South" Blower Controller/Heat Sink.
OR a Bad CCU (Climate Control Unit)

I "Think" your 5-30 Minute "Trouble Free" period of operation is the Warm UP
to Increased Resistance (Caused by the Toasty Warm Air the System is Pumping to You)
If you've already got an Amp draw problem HEAT only exacerbates it.

The Much missed Arthur Dalton has a whole series of Instructions to us
on how to diagnose the Blower system in the archives.

http://www.peachparts.com/shopforum/search.php?searchid=4682493

I recently acquired an inexpensive "Amp Clamp" from "Extech" for just these
type and other issues.

EDIT:

With a Known recently replaced Blower and the clamp on the cable
from the Strip Fuse to the Blower (Over on the Strut Tower),I measure 15 amps with the Blower on HIGH.

With the Amp Clamp on the Positive lead from the Battery to the Connection
Block (On the Backside of the WheelHouse) and the Blower on HIGH I
measure 25 Amps (ALL the other Electrical Users make up the 10 amp difference)

'Both of the above measurements were made with EO (Engine Off).

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'84 300SD sold
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