I just purchased a 1985 500 SEL. The only problem I've had is the fact that it doesn't blow heat. It seems to be putting out heat, but it's not pushing air through the system. I'm assuming that there is a problem with the blower, but I'd like any input as to whether there could be something else wrong before I buy a new blower. Also is this something I can replace myself or should I take it to a mechanic.