Porschefool

Unable to figure out why my blower motor will not operate. The motor itself is fine, it runs when I apply 12v directly to it. Fuse 17 is not blown (84 928s) and blower runs whenever I jump pins 30/87 on either XXI or XXII. Sounds like the control unit to any of you? Other than cleaning all the pins, I haven't really checked it out. Anybody have a pinout or perhaps a write up on HVAC control unit testing?
Does this sound like the internal relay problem I've heard about on these units?
Thanks as always for any input.

Porschefool

Quick follow-up question: I am bypassing the resistor pack by setting control unit to defrost, correct?

Porschefool

Never mind about the resistor pack, I just answered my own question by reading Wally's article on troubleshooting.
Sounds like it's time to tear into the control head.

Jetdriver69

Mine died after squealing for a couple of weeks.

Ordered the new and improved blower from Roger and two hours later, had a better than OEM blower.

Very easy to install and definitely worth the money.

Porschefool

Blower motor works fine with direct power applied, it seems to be a control issue. Any thoughts anyone?

Alan

It is not the internal HVAC relay - that only affects AC clutch operation.

DEF and max speed on the blower switch both bypass the blower resistor pack

Seems the control head is not turning on the on the blower relay - it will do this if it is not plugged in (or if it has a problem).

Alan

Randy V

You would truly be a fool if you don't heed Alan's advice.

Porschefool

Alan is the man, for sure.
I'll be disassembling the head unit this weekend, anybody have a pinout so I can figure out what's what? I'd be happy to just have full blast or defrost at this point...