Now that the heater control valve is changed and tune up just completed, now it is time to find out why the controls don't re-direct the air flow on the climate control system.

First, there is never any flow out of the floor vents. Second, when the slider is on the up arrow shuts everything down, blower, compressor. On all positions except the up arrow, air flows from all outlets except the floor outlets.

Any ideas?
TIA
Glen
1985 928S
Owned for 3 months, on road one month, fixing all the little things the previous owner was too lazy or cheap to do!

 

This system always seems too complicated - they published a manual of about 50 pages on just this subject.

Based on my experiences with this system it sounds like you have vacuum leaks that are not controlling the flaps. This could be in the vacuum line connections or the actual servos that control the flaps.

Or possibly it could be the control unit itself.

Try Nichols tips. Here is the link.


<a href="http://www.nichols.nu/tips.htm" target="_blank">Nichols</a>


Here is also a link to how your system should operate from the Manual.

<a href="http://home.attbi.com/~87928s4/heatingdiagram.jpg" target="_blank">Diagram</a>

 

Hi Glen,

Sounds like the footwell flap actuator to me. I had 2 bad actuators. The rubber diaphragms had little cracks. I pulled the center console and instrument pod to access them. If I went that far today, I would replace all of the actuators when they were accessible. See this link on Greg Nichol’s site for applicable procedures from Wally and company: <a href="http://ourworld.compuserve.com/homepages/nichols/tip509.htm" target="_blank">http://ourworld.compuserve.com/homepages/nichols/tip509.htm</a> I wrote a center console removal procedure that was put onto Greg’s site. Instrument pod removal is documented there too.
By the way, the vacuum manifold contains the solenoids. They control the actuators. The solenoids practically never fail.

See this link for vacuum pump sources:
Mityvac price
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=001362" target="_blank">http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=001362</a>

The following discussion reiterates much of the Nichol’s site information:
AC no more... Help, please!
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=001341" target="_blank">http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=001341</a>

Good Luck,
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

 

OK, sounds like vacuum testing is the next item on my to do list. One quick question though, why would the fan stop, AC shut off when the slider is set to the up arrow? Would a vacuum leak also have this affect?
TIA

 

My temp control seems to have one mode: vent and vent....

The various settings don't seem to work. I can set it to up [my normal setting], down, and both, and nothing changes-air just comes from all vents. If I set it to the big bar, it does nothing.

-A few years ago I pulled my climate control unit apart and changed the little bulb so that it would light up. It's an amazingly complex unit, I'm not surprised that it is not working properly.

My scrawny *** is happiest with warm temperatures-I typically drive around Orlando with my windows open, obviating my need for ventilation-thus my lack of attention in this area.

Normy!

 

Sorry Glen,

I did not focus on that up arrow problem. Could be the control unit in the dash, or who knows? Start with a vacuum check, and let us know. Vacuum pump up the line by the 4 way connector at the brake booster that goes rear through the firewall. If it holds vacuum, vacuum is probably not the problem.

 

Thanks everyone. I ordered the MityVac today from Tool Warehouse. Let you know what happens.
Glen

 

Glen...did you get the kit, the 4050? That's the one I got from Tool Warehouse, but it turns out the included book is actually a bit outdated. It's the book for the standard vacuum only unit, without any mention of what the extra stuff in the kit is for. I whined to their customer service folk, and this eventually got me a couple of pdf docs written specifically for the vacuum/pressure capable pump. They were supposed to be put on the web site soon.

Aha...I just checked. Looks like they are online now, combined into one doc. It's not extensive, but gives a little more info. The doc is at <a href="http://www.mityvac.com/radiatorcap.html" target="_blank">Uses for the 4050.</a>

 

Michael,
Thanks, I did order the 4050. I will download the latest docs.

Glen