No heat in my 5000TQ

[SJ]

This is what I can figure out from the schematic.
The A/C blower motor is controlled in two ways:
1. control by the A/C Blower Control Unit
I think this is the auto blower speed adjuster. If you dont manually select
Lo or Hi blower speeds on the A/C control head, then the A/C control head
will control blower speeds thru this A/C Blower Control Unit.

2. manual control via the A/C control head Lo/Hi speed buttons.


The blower motor is electrically connected like this:
Pin2 > BR wire to ground
Pin2 > BR wire to A/C Blower Control Unit pin C

Pin1 > BK/Y wire to A/C Control Head pin 14
Pin1 > BK/Y wire to A/C Blower Control Unit pin A

Make sure you first test out using the A/C Climate Control Lo/Hi buttons
(bypassing the A/C Blower Control Unit).
I think its bypassed.
Put the A/C control head in economy mode, otherwise nothing will work.

In normal operation, with lo/hi buttons not selected, the A/C control head,
via the A/C Blower Control Unit, will not turn on the blower motor until the
engine coolant temp comes up. Pressing the Lo/Hi button will bypass this
mode and turn on the fan.


SJ
85 Dodge PU, D-250, 318, auto
85 Audi 4k - - sold but still on the road
88 Audi 5kq
90 Audi 100q


> From: "Stricker, Michael" <Michael.Stricker at gd-ais.com>
> Subject: RE: No heat in my 5000TQ
> Hi,
>
> After replacing the HVAC controller (thanks to Chris at
www.Force5auto.com), I can hear the programmer working properly.  The blower
motor still doesn't work.  I have connected it up directly to an adjustable
power supply and it works fine (so the brushes are ok).  I checked the fuse
and it is good.  I suspect a bad ground or some other broken wire since the
HVAC controller diagnostic code for the voltage across the blower indicates
'0' volts.
>
> Not having my Bentley with me, I am at a loss so I was hoping that someone
could tell me what the wiring looks like going from the controller to the
blower.
>
> Thanks in advance.
>
> Mike, 19885ktq



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