Forcing Hot air into the cabin!

[Eiger]

Ok so it's defintely winter and I need hot air to warm up inside my '86 - anybody got any ideas how I can force hot air into the cabin?

All my vacuum lines are intact; heater valve on rear of the engine seems to be working (the little arm pulls in when the engine is running, so my guess is that hot water is flowing into the HV system (no aircon)); solenoids are ok; and I suspect the control unit is dead although the blower dial works perfectly. So until one comes up I need a quick fix. So what can I bypass to get a nice warm flow of air into my freezing cabin in the mornings?

To start I've deliberately undone the notorious heater clip next to the centre console (mine isn't broken) so that it will "fail" allowing hot air into the cabin by design.

Any other ideas chaps?

 

[944 man]

Does the heater matrix get warm? Are you sure that theres sufficient coolant in the system, as the heater is designed to be the highest point?

 

[fossil]

My heater control rheostat has packed up too. If you take the glovebox out-dead easy. remove the covers from the left hand stepper motors, set the bottom heater slide to centre, remove both connectors from stepper motors, put the front motor wiring(nearest bulkhead) to the other motor you can control the heat by moving the lower heater slide on the dash. You then have to control the amount of air to the screen by closing the centre vents as required but at least you have controlable heat.

 

[edh]

I'd get Scotty and 944man to sit in the back seats together []

 

[Eiger]

ORIGINAL: 944 man

Does the heater matrix get warm? Are you sure that theres sufficient coolant in the system, as the heater is designed to be the highest point?

Yes there's sufficient coolant in the system. How do I get to the matrix - it's sealed inside the HVAC isn't it?

ORIGINAL: fossil

My heater control rheostat has packed up too. If you take the glovebox out-dead easy. remove the covers from the left hand stepper motors, set the bottom heater slide to centre, remove both connectors from stepper motors, put the front motor wiring(nearest bulkhead) to the other motor you can control the heat by moving the lower heater slide on the dash. You then have to control the amount of air to the screen by closing the centre vents as required but at least you have controlable heat.

This sounds like a good idea - problem is I don't think my control unit works, so sliding the lower slide won't move the motors - moving them now does nothing.

 

[Eiger]

my "broken" clip idea isn't working. There is hot water in the pipe beyond the heater control valve, so hot water is getting to the matrix.

If my control unit s not working, how can I jimmy the flaps inside the HVAC to allow hot air into the cabin?

 

[appletonn]

ORIGINAL: edh

I'd get Scotty and 944man to sit in the back seats together []

And I'd pay to listen![][]

 

[berg944]

heater valve on rear of the engine seems to be working (the little arm pulls in when the engine is running, so my guess is that hot water is flowing

IIRC The valve shuts off when the engine starts to stop water flowing to the heater matrix, this allows the engine to warm up faster. when the engine is warm enough the valve opens.

I think you might have a faulty valve, try removing the vac pipe from the valve when the engine is warm.

Mike

 

[robwright]

If you disconnect the rod from the servo you can manually open the flap and fix it in position with duct tape or something similar. Ironicly enough many do this to stop hot air coming into the cabin when the unit fails safe. My lower flap servo doesn't work so i have opened it maually and superglued into place to allow air in air all the time to the footwell. What can I say I like warm feet. I also like air conditioned feet in the summer []

 

[Eiger]

I'll give that valve another look Mike.

Rob, you may be onto something there - I'll push and pull that rod and hopefully I can get hot air into the cabin to demist the windscreen in the mornings! My concern is that the temperature mix flap is going to keep directing cold air into the cabin regardless of what I do to the heater rod - or is that rod the one that adjusts that mixing flap (#3 in the diagram below)?

 

[robwright]

As I understand it the HVAC unit has a mixing chamber which mixes hot and cold air at the correct ratio determined by the temperature setting. Mixing is achieved by the flap controlling the amount of hot air into the mixing chamber. I.e full heat - all hot and no cold air. Full cold - all cold and hot air sealed from the chamber. Hence forcing the flap to one direction or the other will result in full heat or full cold. Somebody please jump in if I am wrong. In the diagram you will see as flap 3 rises it essentially seals off the heat exchanger from the flow of cold air being fed in from the blower motor. This can be fresh or recirc depending on the position of the fresh air flap 1.

 

[Eiger]

ok so that's the rod I want to use to reposition the mixing flap for winter. I've got a good flow of air to the windscreen, so #5 is open, and so is #2 as I have some airflow into the wells. Hopefully I'll have a good progress update in the am. Thanks.