slider

Did some searching on this, but no luck. On my 79SC Coupe, I have the defrost controls on the dash with the blower *** located on the of the defrost select ****. Between the seats are the two heater **** - I presume one for the left defrost vent and one for the right.

I don't find a heater blower. Over time, if I lift the heater levers between the seats, the cabin will eventually get warm, but I've been unable to locate the vent blowing the heat or a heater fan.

Am I searching for a function that doesn't exist?

Joe

cmoss

I'm sorry you have a dumb heater. My heater was too smart for it's own good.

Seriously, I had an SC for ~4 years, and never completely figured out the mysterious hearter/fan controls. I wish you luck in your quest...

cmoss

Yes! I admit it! I was just too damn lazy to read the little book.

rfuerst

As a new SC owner I am far from a expert,but the heater fan control is the top lever of the 3 horizontal sliders in the ventilation/heat control unit.The farther to the right you slide the top slider you should here the fan kick in,the highest setting is all the way to the right.The middle slider directs the air flow from bottom to top and the bottom slider helps control the amount of heat I believe,but the amount of heat is also controlled by the 2 levers between the seats,these control the flapper valves in the rear of the car.I don't use much heat in Florida but do use the defrost,hope this helped. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Brian911

not dumb at all, as a rookie my uncle showed me how to operate mine. My 80SC is slightly different in that I only have 1 **** between the seats and the lever. My lever is supposed to be connected to a rod down there but it is not so I just pull it up to get the heat.

My question is that this car came straight from Germany. It is a euro car. Why is my defroster so crappy??? It is very frustrating. It just plain sucks. Anyone know why??? <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />

jet911

Probably the same reason the early VW's heating/defrost sucked. 1st air cooled, thus no radiant heat, 2nd no blower (until later years) to push what hot air was generted by the engine into the cabin. Yep I too find it hard to believe that this part of the car was so poorly designed, especially coming from a country that has COLD winters. Glad mine has the heater blower motor in the engine compartment. I stay nice and toasty!

Regards,
jet
'86 911

NapTownSpeedy

HVAC controls for the 911 are tricky. When you figure them out you have the most infinitly adjustable system available. But I think most of us would trade it in for a more simple system. Here goes.

On the dash there is a unit with three rows of horizintal levers. Starting from the top, the first slot should have two levers. The lever closest to the steering column only travels half the length of the slot. It directs fresh air to either the center dash outlet (far left) or the defrost/footwell vents (far right). The other lever in this top slot controls the FRESH air fan speed. This is a 3 position contact switch.
The middle slot has one black lever. This controls the direction of the fresh air when the small upper lever is full right. Middle lever to the left puts all fresh air to the footwell, to the right fresh air goes to defrost.
The third (bottom) slot has 1 red lever. It acts exactly the same as the middle lever except this time for HOT air. The heat and fresh air controlls are INDEPENDANT. Even though the air exits through the same vents, you are controlling 2 separate air flows.
Now the levers between the seats control how much of the air from the heat exchangers you want in the cabin. Full up on the levers will close the vents on the flapper boxes and direct all hot air to the cabin. Also when these levers are pulled up to any degree, it trips a contact switch at the base of the unit. This turns on an engine bay blower fan. This fan is located on the driver's side of the engine bay, on the top, behind your fuel injection lines. These motors typically fail, are of poor design, and are exposed to way too much engine heat. They will add some heat to the cabin below 2000 rpm, but very little. They are expensive to replace, new or used, and really after 3000 rpm the engine fan will send enough hot air to roast your pinkies off.
I am of the opinion that the SC heat system is the worst that Porsche produced. Be glad that you don't have the funky auto heat dial between the seats. I have done away with the engine blower fan and gone to the pre-75 930 ducts. Less air restriction and it works great. (it's be d@mn cold here and I'm still ok).
If you really want to know everything about Porsche heating systems and how to adjust them her is the site
<a href="http://www.type-911.co.uk/images/exhausts/" target="_blank">Pcar Heat</a>. Too much info, but scroll down to the page you need.

slider

thanks all for your help - I think I got it. I don't ever recall hearing a fan engage when I pull up the middle levers, but I'll listen for it tonight. However, from what Ryan says, if I don't hear the fan start, I probably won't worry about it.

CA Bay Area weather has been pretty awful lately and between being cold in the cabin, or being rained on by bad windsheld seals/sun roof seals, it starts to make the best part of my day (driving home from work) a little less enjoyable.

Joe

Bill W.

Thanks, Ryan. I haven't had the car for long but reading the manual did not help me understand the function of the heater at all. Mine's not a daily driver so I don't get to practice alot but I've printed off your description that I'll keep in the glovebox for my next drive.

Now that the snow/salt is gone all I'm waiting for is the new steering hub and I'll get to take it for a drive!

Fahrvergnuugen

My question is about the fan itself...does it blow cold air into the heat exchangers via these vents?
<a href="http://darklotus.dyndns.org/media/forum_pics/pauls_cars/911/Images/28.jpg" target="_blank">http://darklotus.dyndns.org/media/forum_pics/pauls_cars/911/Images/28.jpg</a>

I have the stock heater blower, but I have no idea where it mounted. The guy who rebuilt my engine removed it because he said it was ugly

I'm guessing it covers up part of the intake?
There are some screw holes on the driver's side...
<a href="http://darklotus.dyndns.org/media/forum_pics/pauls_cars/911/Images/17.jpg" target="_blank">http://darklotus.dyndns.org/media/forum_pics/pauls_cars/911/Images/17.jpg</a>

Bill W.

Paul, see Ryan's Pcar Heat link in the post above. There are several photos and diags. at the link.

Bill W.

Fahrvergnuugen

ahah. it took me a minute to figure out what was going on with that link. i thought it was just a directory full of images...but I found the scanned document.

thanks!

Brian911

Unfortunately Ryan, I do have the dial between the seats. As for roasting my pinkies off...i basically get a little more than room temperature after 3000rpm. I think my heater is crapping out.

Also on the link you provided, maybe I missed it but all I saw were exhaust parts, no heater explanations.
<img src="confused.gif" border="0">

Brian911

Unfortunately Ryan, I do have the dial between the seats. As for roasting my pinkies off...i basically get a little more than room temperature after 3000rpm. I think my heater is crapping out.

Also on the link you provided, maybe I missed it but all I saw were exhaust parts, no heater explanations.
<img src="confused.gif" border="0">

NapTownSpeedy

Brian-
On the link, scroll down till you get to the documents. They are actually scanned in pages from some UK tech magazine. Don't know where it's all from, because I was forwarded the link myself.

As for the auto heat. What can I say, just a bad idea. More than likely your sensors for the heat tunnels,the sensor just above the windshield, or the unit itself ($300 from Porsche)has gone kaput.

If you haven't modded your system at all there are some immediate things to check. The engine compartment blower fan is located on the driver's side near the forward part of the engine bay. You can't miss it, it has 2 black heater hoses running to it. One of these traverses the engine compartment and across the fan shroud. The relay for this unit is under the cover on the driver's side of the engine bay. Check the fuses. If the fuses aren't blown, you should test to see if the relay still works. If the relay works, fuses are ok, and still the fan doesn't work you have 3 options:
1. Forgetaboutit. Survive with no heat (not my choice)
2. Buy a new ($200) or used ($100) fan motor.
3. Go to a used parts supplier and buy the backdate sheet metal (my choice for under $50)

Option 3 gets you the a heater fan scoop on either side of the engine fan. Your current system only has one pickup that sends the air through a maze and a nonworking fan to get to the heat exchanges. Do a search in the archieves both here and at Pelican for backdating heat. Or you could look for my post titled "Stupid Auto Heat" at pelican.

You can remove the auto heat unit. Go to the hardware store and get two more friction washers to make your system's heat lever work like the backdated one's. This saves from getting a new ebrake assembly. BTW, your heater can't crap out. It is just an airbox around the exhaust headers. Now if they are rusty, that's another story.

I just noticed that I am really longwinded. Anyone is welcome to email me specific questions. Check the archieves here and at pelican. This is where I was able to get a good base before working on my car.