[FC] Problem after installing High Volume Blower Motor

[Andrew Sego]

I recently installed a high volume blower fan on the heater in my 63 Corvan. I followed the Tech Guide instructions and wired in a relay to control the high speed circuit. The fan works as before in low and medium, and works GREAT on high. The problem I'm having is if I shut the key off with the fan still on high speed the engine will remain running. Sometimes is stays running, other times it will run on for a few seconds and then die. If I shut the key off with the fan switch in the off, low, or medium setting the engine shuts off normally.

The van is mostly original, except the PO wired in an externally regulated alternator. The regulator has been replaced with a solid state unit, the alternator has also been rebuilt this year. Battery is fresh. Everything was working fine before the conversion.

Here are some details about the installation. I made a strap to hold the heater in place with the transaxle cover off. The brown/orange wires from the fan switch were pulled from the plug, left connected to each other, and insulated with tape along the harness. I mounted the SPDT 30amp relay to the heater brace. I have a new wire running back from the heater switch to the coil on the relay. The ground for the coil circuit goes to the chassis, and another ground wire is also installed to the blower motor flange for good measure. Fused power to the relay (terminal 30) comes directly from the positive battery cable connection at the starter. I chose this location for convenience. The original wire that ran to the blower motor was combined with a new wire and connected to the relay out. The new wire of those two runs to the blower motor. Thus the 87 terminal is a junction for both wires.

I'm wondering if somehow the connection at the starter is a problem, since it isn't switched. Also, does is matter which side of the relay's coil circuit is the power and which is the ground? I'm speaking of terminals 85 and 86. I don't think it does, just throwing it out there.

Aside from shutting the fan switch off before the key, how do I fix this?

p.s. This reminded of the joke: Man says "Doc, my arm hurts when I do wave my arm like this." Doc says "Okay, that's ease to cure...Don't wave your arm like that anymore!"