I Recently purchased, a 1981 Euro 280SE 6 cyl, manual trans, Whata fun car....The mono valve Which actually seems to have two solenoid bodies..makes a soft clicking noise about once
every 4 seconds whenever the engine is running or the
key just in the ignition on position, BUT only after the engine is up to operating temp...Heater seems to function OK... Anyone familiar with this....

Thanks in advance....

Ron C.
'81 280SE
'70 280SE