augustxke

I recently bought a 1986 911 cab. How do you get the heat to work? I pull up on the two levers between the seats and turn the orange **** but the fan does not come on. I found three fuses in the engine compartment and they are intact.What should I look at next?
Thanks augustxke

Amber Gramps

Welcome to Rennlist.

The air/heat was designed to keep you confused. There really is no answer to your question. You can try turning ***** on the dash, but in the end it is designed to do the exact opposite of that witch you want it to do. Do any of you doubt me?

My guess is that the "flapper boxes" under the back seats are frozen shut. Get yourself under the car and you will see the duct work coming off the exhaust. The levers you are pulling on connect to them....

Let me find you a link....

https://rennlist.com/forums/911-foru...ht=flapper+box

https://rennlist.com/forums/911-foru...ht=flapper+box

http://members.rennlist.com/imcarthur/heattrouble.htm

oldskewel

The flappers could be stuck, but that would not explain the fan not coming on. 3 fans actually, one back above the engine, and one one each side by the driver's and passenger's feet.

There are limit switches that should turn the fans on as soon as the heater switch is turned on and one or both levers are lifted up at all.

The most likely cause is a fairly big (for a relay), aluminum rectangular relay in the engine compartment, on the driver's side, near the coil. Just undo a wingnut to remove the panel covering the relay, and you'll see it. Easiest way to test it is to swap with a buddy.

I had this exact problem on my '85, and I believe it is a fairly common issue with those cars.

Once you get that fixed, keep an eye on those footwell blowers and the rear blower. I replaced all of the above not long after I got my car 14 years ago. I think the heaters on cabs get a lot more wear than coupes because people like to drive with the top down even when it's a little cold out.

logan2z

FYI, once you actually get all of the bits working in your car, here's a great thread that describes how to control the heating system in these cars. It's one of the least intuitive I've ever seen and I always forget which lever does what

http://forums.pelicanparts.com/porsc...-87-coupe.html

Pavegeno928

Though a little complicated to operate, the heating system works very well. It's worth the time and effort to fix. Quite a good dual zone set up for heat.

Jay Gratton

All good advice above, I don't have anything to add but I just wanted to welcome you to Rennlist.

augustxke

Thank you for all your responses. The heat does go on when I pull the two levers, but the fan does not go on. I assumed the fuse for the fan was one of the three that I see in the engine compartment. Now that I now it is the relay I have something to go on. I live miles away from the nearest 911 so I probably need to order one. I am about to call automotion to order a front strut so I will order a relay too.
Thanks augustxke

Amber Gramps

You really gotta learn the posting system here. You can continue on with your original thread. please don't take me wrong, post away, just do it in the format intended and you will get all kinds of help.

May I be so bold as suggest you shop around with our site sponsors for struts. Pelican Parts is a great as well as other small business site sponsors. I got my rear shocks from Steve Weiner at Rennsport Systems.

Amber Gramps

Guys our new user has started a new thread to thank us for our replies.

You really gotta learn the posting system here. You can continue on with your original thread. please don't take me wrong, post away, just do it in the format intended and you will get all kinds of help.

May I be so bold as suggest you shop around with our site sponsors for struts. Pelican Parts is a great as well as other small business site sponsors. I got my rear shocks and other goodies from Steve Weiner at Rennsport Systems.

http://www.rennsportsystems.com/

rusnak

Pull the connector and test for 12v with the lever up. Don't just buy parts. Many good parts vendors out there. Don't replace just one strut - pairs, if not all 4 damoers at the same time.

Amber Gramps

I saw that too...that would be a heck of a ride.

theiceman

those rear blowers are notoriously bad .. check for 12v as suggested .. will save a lot of hassle ..

Amber Gramps

Seems I saw somewhere a guy found the motor in McMaster-Carr for pennies on the dollar.

have not found it, but it's out there

https://rennlist.com/forums/911-foru...ghlight=blower

oldskewel

If the "heat does go on," that probably exonerates the flappers.

Trying to save you some time here, but I know different people have different thresholds of how much trouble-shooting they'll do before buying a replacement part. Yours may be very high or very low. Mine varies. When I was trouble-shooting my system, armed with the Bentley manual, after confirming 0V at the footpanel blowers, I went through and tested the heater switch and limit switch. All good. Finally concluded that it must be the relay since everything else worked. Quick swap with my buddy's '88 confirmed and I bought a new one.

Now that I know how it works, something else may help you: when the heat comes on (electrically), all 3 blowers come on at the same time - all on or all off is how they work. So if none of them work, it is not likely that all 3 motors have failed. More likely that the relay or something electrical like a limit switch (but there are two of these, so they'd both have to fail), heater ****, or fuse has failed - one point of failure to kill all 3 motors.

Thinking back, when I got mine, it was in your state. I fixed the relay, and not long after that, one of the footwell blowers started smoking one day. If that happens, immediately turn off the heat, obviously. I found that the bushing had worn and melted, seizing and starting to melt/burn. I just un-plugged the connector going to that blower while getting the new part. Several years later, the same thing happened to the other side. In between those two failures, the rear blower motor started intermittently making loud screeching noises. After taking it apart, I could see that the bushing had worn out.

So, I think when these motors fail, the thing that actually fails is the bronze bushing on the output end of the shaft (between the motor and the squirrel cage). I don't know if they could be rebuilt, but at the time, I did not have the time to investigate that. I think I remember that some of the 3 motors have felt washers next to the bushings that can be periodically oiled (regular engine oil), which should extend the life. But you have to be pretty dedicated to take things apart to oil this.

augustxke

I am still a new comer at this type of comunication hopefully this reply will go to the right spot. I will follow your suggestion,and if I need parts I will use a site sponsor.
thanks augustxke