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Send PMGansevoort, NY - USA
Joined: 12/28/2009
Posts: 7
Vette(s): 1996 Collector Edition LT4
My '96 recently developed a strange issue. First, I'll get the crazy part out of the way. Ocassionally, it sounds like a ping-pong ball is bouncing beneath the dash.(yeah, I know) The heat works intermittently. I'll be driving and then I'll feel heat seeping through the vents. The fan and vent position controls work, but temperature controlled by ghosts! Anyone? Thanks.
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 22714
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
You may have ping pong balls in the system. Well, maybe not ping pong balls exactly, but there may be something floating around in the plenum area that is keeping the temp/mode doors from operating properly. Might have to do some dis-assembly to see what it is.
Joel Adams
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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Send PMGansevoort, NY - USA
Joined: 12/28/2009
Posts: 7
Vette(s): 1996 Collector Edition LT4
Thanks for the speedy reply and the help. Much appreciated.
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9
The floor/vent and defrost positions are all vacuum controlled----the temperature however is controlled via a electronic stepper motor (temp. blend door motor)---the motor assembly consists of the stepper motor, multiple plastic gears and a potentiometer---the potentiometer "tells " the control head what position the blend door is actualy in versus the temperature you have set on the control head.
The gears in the assembly are known to break/crack with age and can make a click/clack/ticking noise and will not move the blend door smoothly/ to the correct position-- blending either heat or AC to arrive at the temperature you (the driver) have requested. Usually IF that is the problem the control head by "looking" at voltage through the potentiometer "knows" there is a fault and lights on the control will flash/blink when the fault occurs. When I had a similar issue on mine and the noise was occuring i could put my hand on the blend door motor and feel it click/clack. The blend door motor is located inside and on passenger side and can be seen/felt (if you're a contortionist) up next to the firewall----motor is black, has a electrical connector and is about half the size of a pack of cigarettes.
Vaughn
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Send PMGansevoort, NY - USA
Joined: 12/28/2009
Posts: 7
Vette(s): 1996 Collector Edition LT4
Vaughn,
Thanks. I noticed the light flashing on the temp controller and was wondering what it could be. I really appreciate the help. I won't have to wait for the Carlisle seminar to fix it!
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in Forum: C4 HVAC, Fuel, Emissions, and Exhaust
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