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Discussion Starter #1
08 with 120k on it. Only have a little air movement coming out of air vents. All 4 speeds work. New Delco resistor and complete harness kit last year. Inspected all terminals. Not burnt at all however, the blower plug toasted a 3rd time in 3 years. Last year ground the fender grounds to fresh metal and electrical greased. Re-did again today but looked clean. Bought a Delco replacement terminal for toasted blower plug. Smelled it burning when blower quit then all speeds were dead. Bought new motor today too. ALL CONTROLS work and cables both move fine. AC turns on/off. Compressor works fine. Not sure on recirculated air switch yet. Could one of the doors inside hvac housing be stuck? Air movement from any vent equals about the # 1 speed. Could the resistor have puked out 2.. 3 and 4 speeds with ZERO burnt terminals in resistor? Had all good fan air movement before the motor plug toasted. Everything works now but like it's on #1 speed now.
 

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Has this been the issue since last year when you replaced the resistor and harness and cleaned up the grounds?
 

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In my experience on previous vehicles, if the resistor craps out the blower will only operate at full speed (when the resistor is bypassed).
 

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In my experience on previous vehicles, if the resistor craps out the blower will only operate at full speed (when the resistor is bypassed).
That's because high speed has no resistance from the resistor like the other speeds do to slow them down.
 

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Discussion Starter #5
Has this been the issue since last year when you replaced the resistor and harness and cleaned up the grounds?
No. This issue of very little CFM (if you will) started after the latest blower plug burning up. I have all four speeds and OFF at the fan switch. Has anyone had the "Recirculation" switch go bad on them? I always had it OFF and fresh air coming in being a smoker and crack my window open to suck the smoke out. It's seeming like a door inside the housing isn't where it should be. Like cutting off the blower air or most of the fresh air not coming in.
 

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If I remember correctly, on my Comanche one of the doors was operated by a vacuum solenoid that was controlled by moving a lever on the HVAC panel and the other had a cable connected to another lever. Our trucks have knobs that serve the functions of the levers. Not sure if the doors on our trucks are vacuum operated but if so it could be a loose vacuum line.
 

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Discussion Starter #7
If I remember correctly, on my Comanche one of the doors was operated by a vacuum solenoid that was controlled by moving a lever on the HVAC panel and the other had a cable connected to another lever. Our trucks have knobs that serve the functions of the levers. Not sure if the doors on our trucks are vacuum operated but if so it could be a loose vacuum line.
I'm seeing an actuator of sorts in the diagram for the whole hvac assembly on the blower end of the hvac box. I know the temp control and the defrost/ vents/floor are cables and work fine. Also the diagram for the hvac box shows 3 different doors. I suspect one of the 2 middle doors isn't working. Strange happening when just the blower plug fried though.
 

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The air temperature and mode doors are controlled by cables. The recirculation actuator is electrically controlled by a motor.

Another cause can be a blocked "body pressure relief valve", which would basically mean the fan would be trying to blow air into the cab (assuming doors/windows are closed) and there would be no place for the new air to to to in the cab. (Do you have to slam you door to get it to close?) Try testing the air output with a window or door open. On my S10, the vent was below the back window, between the cab and the bed. Not sure where the 355 one is.

Good luck!
 

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Discussion Starter #10
The air temperature and mode doors are controlled by cables. The recirculation actuator is electrically controlled by a motor.

Another cause can be a blocked "body pressure relief valve", which would basically mean the fan would be trying to blow air into the cab (assuming doors/windows are closed) and there would be no place for the new air to to to in the cab. (Do you have to slam you door to get it to close?) Try testing the air output with a window or door open. On my S10, the vent was below the back window, between the cab and the bed. Not sure where the 355 one is.

Good luck!
So again I'm a smoker. I crack the window open for fresh air (not recirculating air) from outside to force smoke out. It still barely does that. Truck has always been super tight when closing the doors when all windows are up. Actually too tight imo. Maybe relief valve is blocked but can't be the problem if my cig smoke will barely get out my window. So again the blower works great but it sounds labored. Like a door or doors are closing the fan almost completely off inside the hvac box. Wasn't a bunch of crap on top of the screen above blower when I changed it either. Does the dash have to come out to get at the hvac doors? Can't really find that procedure in here either.
 

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It's only a 0.3 hour job to replace the fan per the manual. I'd pull the fan and look inside. Maybe some thing got in there and clogged up the fan blades.
 

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Discussion Starter #12
It's only a 0.3 hour job to replace the fan per the manual. I'd pull the fan and look inside. Maybe some thing got in there and clogged up the fan blades.
The problem started when the motor plug fried. Figured maybe was a tired motor drawing amps with maybe worn out brushes replaced with new fan. NOTHING inside the housing to block it. The new motor is blowing hard. Barely getting through all vents. All speeds work. Going to try a new cheap resistor tomorrow. Nothing burnt at all on those plugs terminals or harness. Then I'll have a spare at least if it don't fix it. Doubt it will as blower speeds all working.
 

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Discussion Starter #19
Any chance the motor is spinning backwards??? I'm just guessing - it is a DC motor. Could you have flipped the leads to the motor with the plug replacement?
Well... yes!! I've been a little distracted with some heavy family burdens lately. I even blacked out one of the 2 replacement plug wires. Still wasn't paying enough attention. Spinning backward motor will ONLY BLOW A LITTLE bit through your hvac system. This is a hard learned lesson to pay attention! I'm never thrilled with wiring but normally good with basics like this. Thanks guys for all your suggestions! The idiot factor never entered my mind! :ROFLMAO:
 

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Well, I'm an ex submarine electrician with an electrical engineering degree...I've seen this in places where the impact is a bit more significant...

Peace...
Ken
 
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