aeg double oven 944171533

hi guys a bit of head scratcher this:mad: customer said wasnt heating up .. went out armed with a new element ..looking for a easy job .. tried it fan ect working . took cover off and element was working . . so was puzzled so was customer . tried it again worked for 2 mins .then tripped the rcd .. so i changed the element ,, was worse trips after about 20 secs ..now the fan motor not working .. bizzare took it out top off .. as could smell burning .., was thinking the selector switch . or the small thermal limiter in plastic case with the 4 small wires ,but doesnt look burnt out either remember they were common to go .. that small thermal limiter . if gone completely now would it stop the main fan oven motor ? and would it trip the rcd … ? the element heats up fine .. top oven ok too ? am totally puzzled now .. also they have just had a new fuse board fitted .. to confuse things more ..