The vacuum relationship had appear from the heater valve, as well as the totally free stream of air triggered the hissing seem with the heater Command. Connecting the vacuum hose on the heater valve cured the hissing seem, and shut off the circulation of coolant from the heater core. See also the notes beneath below Vacuum Look at Valves. See Guida

Many thanks in your concern regarding your 1997 E320. The blower motor in your automobile is under the passenger aspect dashboard. If you can obtain to The underside with the dashboard there must be a plastic panel to the passenger facet you'll be able to eliminate to reveal the blower motor.I had precisely the same difficulty by using a ten-yr-out