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Old 08-12-2003, 01:09 AM
rrobben rrobben is offline
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Join Date: Jul 2003
Location: Louisville, KY
Posts: 41
Is a Heater Supply Unit the same as a Duovalve?

All,

Thanks for listening! I'm having heating problems with my 93 500 SEL. The DTCs are:

E0 74 Heater supply unit circulation pup (A31m1), open or short circuit *)
E0 75 Heater supply unit circulation pup (A31m1), open or short circuit **)
E0 83 Heater supply unit left duovalve (A31y1), open or short circuit **)
E0 87 Heater supply unit right duovalve (A31y2), open or short circuit **)

Can someone tell me if the heater supply unit and the duovalve are the same part? Do they come together, or can they be replaced separately? I'm a newbie, and I need some help please!
__________________
1993 500 SEL 121,000
2003 Toyota 4Runner 4X4 Limited (Sweet!)
1995 Ford Bronco 351 Windsor 135K miles (Hunting truck)

Past Vehicles
1999 Landrover Discovery II 46,000 (Sold)
1998 Lexus ES300 (Sold to get my Benz)
1973 Chevy Nova SS (drove it till the body fell apart in '87)
1971 Chevy Camaro (wrecked in high school)
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