With the wires pulled off the monovalve coil, the valve should be wide open or full heat, regardless of what the ACC system is doing. If you have no heat, you could have a stuck monovalve (especially if it's the MTC brand), a problem with the heater core, or could be a problem with circulation. I'd expect you to still have SOME heat even if the Aux pump had failed.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]