86 autoheat no work

[mdurbahn]

hey guys, I am trying to get the heat working on my 86 911. The a/c works perfect. The heat doesn't work no matter what I try to do, the defrost blows alot of air but it's cold. I don't think the flapper wheels are closing in the engine compartment, when I try to move them closed by hand the spring back open so I was thinking that might be the issue? Any tips on how to diagnose this?

[proporsche]

1st remove on the heater control unit right side cover..there you should see little rod and a ball joint.It is possible that it is disconnected..report back

ivan

this 16 part of the 19
https://www.design911.com/uploads/diagrams/908-00_911_1987-89_NO1.gif

[mdurbahn]

Thanks I will check that first and see!

[mdurbahn]

The rod is connected. I don't think it is moving completely though, I have taken a picture of it at the 0 position and 8 position for reference.

[proporsche]

looks like that it opens pretty much..Also looks like somebody has replaced the ball joint already ..maybe some adjustments on the rod might be left?

Do you hear the position being changed while going through the numbers up to the 8? Also check the sensor with a blowdryer.
if it does it there are couple of things which could be checked the sensor itself and also the control relay in the engine compartment.

Ivan

and here some reading
https://members.rennlist.com/imcarthur/Heatrelay.htm

[mdurbahn]

OK, I have checked two thingss.. First the blow dryer on the sensor will make the rod move open again. Second I popped off the arm and was able to push the pivot shaft back further and get heat from defroster. It was very hard to push back with one hand and would spring forward unless I held it back. How hard is this supposed to be to move? I think either my cables are bad or the servo motor is too weak at this point.

[proporsche]

it is quite hard to push with hand ,that is normal i would try adjusting your rod and ball joint.The sensor is working and the unit is responding also maybe adjusting the cables at the flaps....

Ivan

[tomphot]

My '85 had Autoheat. They are very hard to get working right and spare parts are impossible to find. I finally threw in the towel and converted it to manual controls.

[mdurbahn]

Originally Posted by proporsche

it is quite hard to push with hand ,that is normal i would try adjusting your rod and ball joint.The sensor is working and the unit is responding also maybe adjusting the cables at the flaps....

Ivan

Thanks I will try that, you can adjust them from underneath the car?

[mdurbahn]

Originally Posted by tomphot

My '85 had Autoheat. They are very hard to get working right and spare parts are impossible to find. I finally threw in the towel and converted it to manual controls.

How difficult is it to change to manual?

[proporsche]

yes you have to have the car in the air to adjust the cables,also adjust the rod-ball joint length
Ivan

[cpa]

If the cables and heater boxes are all working and you need to adjust the actuator rod in the control unit the length between the ball socket centers is 124mm. (Bentley Manual) You can pop it off and set the length for full travel. The auto temp control can be frustrating, but when working properly there good.
If you think the control is not working properly and don't want to repair it yourself contact Kris Rose,
jamesDean59@gmail.com he can repair it at a reasonable cost.

[mdurbahn]

Originally Posted by cpa

If the cables and heater boxes are all working and you need to adjust the actuator rod in the control unit the length between the ball socket centers is 124mm. (Bentley Manual) You can pop it off and set the length for full travel. The auto temp control can be frustrating, but when working properly there good.
If you think the control is not working properly and don't want to repair it yourself contact Kris Rose,
jamesDean59@gmail.com he can repair it at a reasonable cost.

Thanks that is great info I will set that length at 124mm and give it a try!

[manbridge 74]

Last two auto heat cars I repaired both needed relay/controller in engine compartment to have all speeds.

[proporsche]

Originally Posted by manbridge 74

Last two auto heat cars I repaired both needed relay/controller in engine compartment to have all speeds.

yes this..^^^^

i have couple of those relays if will need it

Ivan