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Looks like there is no valve - which means hot water flowing all the time....I guessWho knows as the V6 in a series IV is not stock. You should be able to follow the heater hoses around to locate, if in fact there is one. Stock on a series IV was on the firewall near where the heater hoses go through the firewall to the heater core. I've seen them removed due to being faulty and either no hoses running to the heater core or an "on all the time" situation where engine coolant is running through the heater core full time without a valve.
Rick