The Porcupine is a resistor array changing voltage to the blower motor, thus changing speed. The controller box selects input to the various resistors.
No, the porcupine is the heavily finned (with circular cross-section heat-dissipation 'spines') blower speed regulator that lives in the air plenum by the blower motor. It's solid-state, and is likely just a power transistor or three. (I've never chiseled one open.) They are found in the '86+ ACCII's, the ones with the large black AUTO button and with non-discrete blower speed steps. There is no separate speed controller box, they take an output directly from the PBU, which also contains the brain. The porcupines are, sadly, not immune from failure.
The controller box (full of relays) is associated with an old-style box full of dropping resistors, usually on the fender or in the air intake under the grille. It does the same job the manual switch used to do, but under automatic control. It's separate from the PBU, and from the cabin temperature regulator box. They are not failure-prone. -- Jim _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
