Confused w/Heating?

[michaelw]

Just tried the heat on my 87 targa and found it's not working. Went to owners manual and first found the heating control I have between my seats is only a 3 position type versus the 10 position automatic system shown in the manual.

Bentley states that the 2 options on 87's were an automatic system like the one shown in the owners manual or a manual system with/out I'm assuming, a unit between the seats. Also my car has the emergency heat levers that you can pull up which neither Bentley or the owners manual shows.

What's going on? Did someone backdate my heating system? Could someone tell me what they have on there carrera and how it works? Then I can get into diagnosing the problem.

Thanks,
Michael


[This message has been edited by michaelw (edited 10-30-2001).]

[Eric H]

Hi Michael,

My '87 has the manual controls. The knob between the seats goes 0-1-2-3, not 0-10 or whatever. The two red levers on either side of the emergency brake control cables that close the heater flaps under the car as you pull the levers up. They also turn on the engine heater blower as soon as one is lifted, and I believe mine also speed up the footwell blowers as you raise them. This all happens with the control on zero. I think turning the control up runs the fans faster but allows you to keep the flaps open so it's not so hot. I could be wrong, though - it's not the most intuitive system!

I think the manual system is less problematic and more flexible than the automatic system, and you're right - it's not in Bentley or the owner's manual. Eric H 87 Targa

[michaelw]

Originally posted by Eric H:
Hi Michael,

My '87 has the manual controls. The knob between the seats goes 0-1-2-3, not 0-10 or whatever. The two red levers on either side of the emergency brake control cables that close the heater flaps under the car as you pull the levers up. They also turn on the engine heater blower as soon as one is lifted, and I believe mine also speed up the footwell blowers as you raise them. This all happens with the control on zero. I think turning the control up runs the fans faster but allows you to keep the flaps open so it's not so hot. I could be wrong, though - it's not the most intuitive system!

I think the manual system is less problematic and more flexible than the automatic system, and you're right - it's not in Bentley or the owner's manual. Eric H 87 Targa

Eric - Thanks! I am trying to test whether the heater motor/switch is working. If you turn your ignition to the on position before starting and then switch your heater control nob to position #1, do you hear the fan blowing?

Michael

[R22tech]

o.k. this is straight out of the manual:" The heating air can be controlled seperately on the driver's and passenger's side by a rocking lever. when the lever is pulled up, the heating is on, when down, the heating is off. In order to boost the defrosting effect, 2 aditional blowers can be switched on by using the 3-stage rotary switch when the lever is raised. additional blower switch in position

0- Blowers off
1- Blowers operate at low speed
2- medium speed
3- top speed "

If you look on your dash at the sliding ventilation controls, you will see the bottom lever is red. This lever regulates the heating air flow as follows: left position=footwell air flow
center position= lower and upper compartment areas
right position= air flow is directed upward only.
I hope that clears things up for the winter.

Michael- I assume after reading this you know that the blowers operated by the rotary switch WILL NOT COME ON unless you activate heating system by pulling up on one of the red levers.


[This message has been edited by R22tech (edited 10-30-2001).]

[This message has been edited by R22tech (edited 10-30-2001).]

[michaelw]

R22tech:

Thanks, that does clear it up abit. My manual makes no mention of what you stated to operate the heating system. It only gives instrux on using the automatic heating system, hence my confusion.

I just ran out and started the car and pulled up on the heat levers. My original problem still seems to remain, in that when I do turn the heat on, it comes out fine, but when I turn the switch from 1-2-3 to defrost, there seems to be no change in airflow. When you do this, do you notice a difference, like an increase in blower noise? Michael

[This message has been edited by michaelw (edited 10-30-2001).]

[Bill Douglas]

Hi Micheal.

Try putting the back of te car on axel stands and get underneath. You will see the two flapper boxes that the hoses from the heat exchangers go to. Get someone in the car to pull up on the red lever and you will (hopefully) see the flapper boxes closing to redirect the hot air into the car. If that works yell a few more instructions to your wife/niebour/ex-friend to work the automatic switch thingie and see if that works and what it does.

If the flapper boxes don't move it may be a cable problem.

Bill '79SC

[R22tech]

Michael- Mine does exactly what yours does: No change in air flow or blower noise when i turn the dial from 0-3. I have no idea where these auxillary blowers are, and really, it doesn't concern me. My car will toast me out by just pulling the levers up and since my car stays in the garage- really no need to defrost, which is what the sole purpose of that dial is! If you need more info. on how to adjust the heat/air for specific needs, just ask and I'll tell you how to do it properly. Although, the HVAC system in our cars is confusing, it can be very rewarding if adjusted properly. And it can do stuff most other autos can't; such as heat and cool at the same time!

[R22tech]

I just read your posts again. Let me re-clarify: The red levers between the seats ARE your heating controls and NOT some sort of emergency heat levers. The rotary knob between these red levers is for a BOOSTER for DEFROST ONLY- it is NOT your heating control. The amount of heat you let into the cabin is DIRECTLY PROPORTIONAL to the amount you raise the red levers. IE: raise the left lever just a little=just a little heat on the driver's side; raise the right lever all the way up=a whole lotta heat for the passenger side! Get the picture?

[Argo]

I've been dealing with this same problem and it gets a little more complicated ... on my 88, the levers open the flappers & allow heat from the exchangers into the cabin (pushed by the large engine cooling fan). When the lever(s) are up, heat will flow into the cabin. To supplement this flow, there is a rotating switch just above the levers; this switch operates auxiliary blowers in the footwells and the engine compartment. This extra blowing can be directed to the footwells *or* the window to defrost by the lowest dash lever. These blowers are controlled by the heater blower relay in the engine compartment (left sidewall under the black plastic cover held on by a wingnut). There are 2 aluminum covered relays there; the smaller one closer to the rear is for the blower motor (the other is for the rear window defrost I believe). There are also 3 fuses below the relays; I believe the bottom 2 are for the blower. On my car, the engine blower motor was toasted. It sits on the top left (drivers) side of the engine connected to the shroud/duct surrounding the cooling fan and another black plastic duct carrying the heated air into the cabin. Apparently these motors have design flaws and blow out fairly often (bushing holding shaft wears out); when this happens, it can also toast the relay (as it did in mine). If the other suggestions on this thread don't work, pull this blower motor and test it for function; it's easy - 3 nuts and the ducts hold it in place, it's east to reach and there is only one 2 prong plug connecting it to power. If it's blown, the footwell fans won't work either. If it works, suspect the relay. John Walkers Workshop gave me some tips on testing this relay; search for a thread titled "need help ... wiring diagram for a '88 911". If the motor and/or relay are toast, you can get replacements through partsheaven (they have a better replacement motor ($195 with complete box; $125 for motor alone (save your squirrel cage) and used relays for $10 (around $70 new from pelican). Search this site for more info; there's lots of relevant threads and it seems like motor/relay failure is not uncommon. My motor and relay should arrive in a few day so I'll see if this is my solution. I think i've got this figured out, but anyone else feel free to make corrections. Hope this helps ......

Argo
88 Targa

[Argo]

I forgot to mention, on earlier models the switch was attached to the red levers so that the blower motor would go on whenever the levers were raised. These switches were replaced with the rotary switch (early 80's?); with rotary switch, the levers just open flappers and allow heat access to the cabin. The large engine fan provides some blowing all by itself, but not enough to defrost the windows when the engine is only idling. Thus the auxiliary blower motoer.

Argo
88 Targa

[masraum]

Uh, yes, sounds like things have been pretty well covered. To offer just a tad more... The red levers have to be pulled up for the heat to do anything. The knob in between them is listed as off, low, med, and high, but in my car and some other's cars it's low, low, med, and high. It only controls the auxilary footwell blower motors which are behind the two kick panels in the footwells on both sides and also commonly freeze up blowing the little inline fuse that is in the wire that plugs into them. When you pull up the lever and then twist the knob to 3 it should be quite loud. If not pull the kick panel and check the inline fuse(assuming you've checked all of the other fuses).

Mine has worked fine until the other day and it just stopped, but I haven't had the chance to really check it out yet other than I know all of the fuses are good, and the footwell blowers aren't getting power.

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Steve
Rennlist Member
PCA Member
'88 targa

[Kurt peterson]

Consider yourself lucky. I have an '87 930 with the electronic system and I also have no heat. The control unit is getting power so my only alternative is to buy a new heater control unit. I'm afraid to ask how much it is. Maybe I'll just wear a thicker coat in the winter.

[wckrause]

Kurt, on my auto heat system ('79 SC), you can seperate the auto control from the lever by removing a screw. You can then operate the system manually. I don't know if yours is the same but its worth taking a look. The screw is right about where the lever comes out of the unit, near the e-brake handle. I've operated mine that way for ten years.



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Bill Krause
'79 911SC Euro
MY PELICAN GALLERY

[Roy M]

I have an automatic system but I found the info. contained in this link (about half way down the parts list) very useful to understand what was happening.

Roy


http://www.type-911.co.uk/exhaustparts.htm

Easier Links for direct access

http://www.type-911.co.uk/images/exhausts/heatingtech1.jpg
http://www.type-911.co.uk/images/exhausts/heatingtech2.jpg
http://www.type-911.co.uk/images/exhausts/heatingtech3.jpg
http://www.type-911.co.uk/images/exhausts/heatingtech4.jpg
http://www.type-911.co.uk/images/exhausts/heatingtech5.jpg
http://www.type-911.co.uk/images/exhausts/heatingtech6.jpg

[This message has been edited by Roy M (edited 11-01-2001).]

[michaelw]

Roy:

Thanks for the links, I think those along with the awesome advice posted above will help me figure it out. It sounds like my forward auxiliary motors are not working. Next the a/c!

Michael

[emcon5]

Originally posted by Kurt peterson:
The control unit is getting power so my only alternative is to buy a new heater control unit.

For an overly complicated Rube-Goldberg device, the things that go wrong with the auto heat box are pretty limited. With the ignition on but engine off, if you turn the knob to full hot you should hear the servo running inside the box. The first thing to check is that the little arm connecting the servo to the cable actuator is connected. When I got my car, it wasn't. If it is connected, look under the car at the heater flapper boxes. They should be open, so they vent the hot air outside. With the ignition on/engine off, turn the knob to full heat. Look again, they should be closed. If the automatic heater control is working, and the cables are intact, the flapper valves should close and direct the hot air to the cabin. If the servo is connected to the cable actuator, and the servo is moving but the flappers don't move, there could be a problem with your cables.

The other potential problems with the auto heat unit involve open circuits to the two temp sensors. One is located by the rearview mirror on my SC (not sure where it is on a turbo), the other is by the heat exchangers (but I have no idea where). Indications of an open circuit to the cabin sensor are full heat regardless of setting on the controller. This was also a problem with my SC, I removed/cleaned/reinstalled the cabin sensor and it has worked fine since. I can't remember what the symptoms of an open to the heat exchanger senssor was, but it is in the Bentley manual, and I can look when I get home.

Worst case, the controler board could be shot, and then you are screwed. Your best bet wouold be to swap it with a good used one, or backdate it to the manual levers.

Tom


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82 911SC Coupe

[This message has been edited by emcon5 (edited 11-01-2001).]