86 Center Dash Vent Question

CrossT · 11-19-2002, 12:20 PM

Saw a few threads recently about A/C or heat. I guess that depends on whether you're on the bottom or top or the globe . . .

My question is in ref to the center dash vent of my 86 cpe. I get virtually no air out of the center vent, regardless of A/C or other ventilation setting. There is a decent amount out of the sides, but none out of the center. Assuming this isn't normal, does this sound like blockage, linkage, hoses, flapper . . . . ? I don't pretend to understand the system, and looking in the front bay further reinforced my lack of understanding.

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Todd Shallcross
86 Carrera Cpe GPW

RoninLB · 11-19-2002, 12:40 PM

Makaio may be of some help.. he did work on an SC AC vent system.. my AC system was different............Ron

steve911 · steve911's Garage

Todd--
welcome to the vagaries of the 911's ventilation system. the center vent is AC only, I believe. If AC is on, do you get air movement when the fan is switched on (its to the right of the AC temp dial in the console of my '85)?

Does the AC fan work? could be fuse and/or relay.

hope this helps

Eric Coffey · 11-19-2002, 01:12 PM

Bad evap. fan in the smuggler's box?

CrossT · 11-19-2002, 07:19 PM

Thx guys,

A/C fan does work as I get air cond out the sides and the bottom.

I'm beginning to think it's either blockage or a disconnected hose.

thanks for any further opinions . . .

todd
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86 Cpe

Eric Coffey · 11-19-2002, 11:28 PM

The center vent is indeed for A/C only. You can also mix the A/C with the fresh air from the side vents. However, you can not get A/C from the footwell. So, you are probably getting fresh air from the sides and bottom (not A/C), supplied via the fresh air blower (big plenum behind the cardboard panel in the front trunk). the blower that controls the center A/C only vent is in the evaporator fan in the smuggler's box. I would check that first.

FYI: there are 6 blower motors in your HVAC system!

Good luck!

Calspeed · Calspeed's Garage

Hello,

I noticed that recentely the center toggle on the HVAC controls will not go all the way to the left side. I felt underneath and back and noticed that the cable is bent at the end thus preventing full movement.

How do I go about taking this thing apart? I want to make the repair as well as preventive lubrication.

Michael

CrossT · 11-20-2002, 09:15 AM

Holy %$#%$#, 6 air blowers.

I've re-checked the A/C blowerr operation and it does come out the sides and the bottom center. There appears to have been some mod done underneath. Two 2" or so holes drilled I assume to let more air out the bottom for A/C. There are two tubes opening out of approx the same diameter inside. The A/C comes out there as well as the sides. I wonder if they somehow plugged the dash center vent to force it out the bottom. If I plug the two tube outlets, there is no add'l air forced out the dash vents. Hmmmm . . .

Being previously aware of only two motors, I've gone and paid a visit to the car and now know of 5.

One, Evap in the smugglers box (Works)
Two, Heat (?) at the footwells (Don't seem to work!)
One, Heat blower in eng compartment (Doesn't work either)
One, Fresh Air inside dash (Works, but can't tell where the air comes out)

Is there another?

"Fascinating" (well, that's the most positive word I can think of). Appears to be a system that Porsche cobbled together over the years to add capability to a rudimentary ventilation setup.

todd
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86 cpe

Eric Coffey · 11-20-2002, 12:51 PM

CrossT -

Technically, you are right. There are only 5 blower motors that bring air into the cabin. The 6th is the front A/C condenser blower in the front trunk (in front of the gas tank, next to the battery). Anyhow, it sounds like you have a "custom" setup. If the fresh air and evap. fan are in working order, I would check for after-market (homemade?) ducting, or vent block offs. Also, check all the cables at the back of the dash control module, as well as each flapper for proper operation. Keep us posted!

Calspeed -

I believe you need to remove the center heat/fan control module, then the e-brake assembly, which includes the two heat levers. Once you have that off, it should be easy to see what is going on in there. If you need more info, just post a separate new topic.

CrossT · 01-27-2003, 09:44 AM

Now, I'm not the quickest at getting around to things, but I eventually do. The 4 kids leave little time for such 'lowly' hobby activities. I wish I had more time . . .

Anyway, I finally have diagnosed the cause of my 'no airflow' condition in the center vents. The PO had a couple of large holes cut into the duct leading from the evap blower. This duct is hard plastic and angles up from the evap blower and into the ducting and on to the vents. With these holes, the air pretty much all exits to the underside of the dash through two more large hole 'hole sawed' into the firewall. A vent was place here too.

I got into the smuggler's box and, cheapo that I am, duct taped the inside of the duct where the holes were cut. I now have good airflow to tall three A/C registers on the dash. We'll just have to wait and see if the air is actually cold when the temps warm up in Apr or May.

Enough of the followup. The real question I have is related to the equip in the smuggler's box. While in ther, I noticed a bunch of &^%$# in the bottom of the box. Makes me wonder if the airflow thru the evap is being restricted. I'd like to clean the are out, if possible. What is removable here without disturbing the system to the point it will need to go in for service? Can the blower be separated from the evap? Is it all one piece? If it is removable, how?

any suggestions would be appreciated

thx,
todd
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86 cpe

scottb · 01-27-2003, 10:28 AM

Todd: Call Charlie Griffiths at www.griffiths.com. He sells a rebuild kit for the evaporator box. The kit lets you open up the box, clean it out, replace the gaskets, and re-seal. Also, if you're going to open up your system, you can remove the evaporator and clean it out (or replace it). Charlie knows his stuff when it comes to Porsche a/c. It will be worth you time to give him a call.

Scott

Argo · 01-27-2003, 10:41 AM

I noticed my evap fan starting to squeal last year; according to Bentley (IIRC) you have to purge the freon to access the blower fan. I seem to remember someone else here doing the fan maintenance w/o purging. Anyone here have any experience w/ squealing evap blowers? TIA.

Argo
88 Targa

CrossT · 01-27-2003, 03:06 PM

Argo,

I also seem to remember an older post on this whereby someone was able to do some work on the fan w/o purging etc. I did a search before posting this and came up empty. Maybe I'll get adventurous this weekend. There's $200 worth of R-12 in there I don't want to disturb . . .

Scott,

I've talked to him before. He's definitely knowledgeable. The junk in the box appears to be old pieces of seals/weatherstripping, etc. So, a reseal kit might be the ticket, especially if it didn't require purging/recharging.

todd
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86 cp

scottb · 01-27-2003, 04:09 PM

Todd: My recollection is that once you open the smuggler's box, the fan is on top of the evaporator box and is accessible *without* removing the a/c lines (which would entail recovering the r12). On the other hand, if you're going to do the job right and remove the entire evaporator box for cleaning and resealing, you'll need to have the r12 recovered.

PCA7GGR · 01-27-2003, 05:21 PM

The A/C needs to be evacuated of freon prior to disconnecting the hoses to get the fan/evaporator out. An alternative is to get at the underside of the evaporator from the passenger compartment.

Remove the passenger side foot board and you will see a port with a thermal switch. Disconnect the electrical lead to the switch and then remove the switch. If you are careful, you can then clean the underside to the evaporator on which crud can accummulate. Good luck.