strange noise and low air flow

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on my '94 i have noticed the last couple of cold mornings a strange noise coming from around the passenger dash area when the heater fan is on. it sounds like a cross between and rattling and vibration noise and the air flow through the vents seems to be low or restricted in some way. i did a search but found no discussions of similar problems. could it be a loose vacuum line or something related to that. any suggestions are appreciated. thanks in advance. .

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'94 2500,4x4,SLT,auto,
3. 54,Prime-Loc,TST #6/230, 75,000 miles

 

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On my wife's Isuzu Redo, I had the same type noise. We had just got in to it to go to CO. Turned the blower on and man what a noise. So I took the blower out and found that some mice had built a nest in the fan. I don't know if it is the same thing, but you might check it out. I don't know how hard it is to take the blower out, on the Isuzu, all I have to do is take four screws out. GOOD LUCK.

 

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It sounds like the pull cable has come off the flapper valve in the air duct. Does anything change when you turn the knob that selects where the air is supposed to go? If it doesn't pull the knob off and see if it's ok. These knobs are kind of flimsey and the center can fail so it just turns without doing anything. If that's ok then you need to look at the pull cable end. This is kind of a hassle. You have to lower the steering column. Make sure you disconnect the cable to the gear shift indicator. The clamp that holds the steering column up has a ground wire terminal. Be carefull of that gadget. Remove the screws the fasten the dash at the bottom of the windshield. Then loosen the large bolts that the dash hinges on at bottom of the ends of the dash. If everything is ok (I may have forgot something) you can roll the dash board back and get at the top of the heater duct. Oh yeah, disconnect the batteries before doing all this or the air bag may go off. This happened to me once. I ended up haveing to replace the cable from the knob to the air duct valve. You may get away with just pushing it back on the lever at the top of the air duct. All this is kind of a hassle to do, especially if this doesn't turn out to be what's wrong. You may just have a mouse living in there.

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Joe George
Eureka, CA

'95 2500 CC auto 4X4,3. 54,Combo EGT/boost guage,custom switch panel,PacBrake,TST #5,BD valve body,Automatic motorhome steps on both sides,Foldacover hard bed cover,Cummins chrome kit,Black steel grill guard,Front hitch receiver

 

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Joe... the air does go to the directed place when turning the knob, but just not much air flow, and the noise is not constant, plus it seems to go away if i rotate the selection knob between say the floor setting and the dash setting... . it just may be a critter in there with a nest... i will investigate this weekend..... thanks again