Luke warm heat 92 Eco

[8v-of-fury]

I think they can be had for under $50. OR close to it, a very very useful tool! I use it in brewing too

[92EcoDiesel Jetta]

You can buy an IR thermometer from HF (where mine is from) or Radio Shack. Everybody sells one just about.

I dug out my spare heater/AC box from the 91 Eco parts car and studied its operation a bit. The blend door is the one with 10 holes closest to the firewall. The one with 3 holes is not called a blend door I don't think.

There is no foam on the blend door or the 3 hole door. Was the holes supposed to be covered by foam? Why put the holes there in the first place if when the foam falls off, it stops working as a blend door? WTF? Someone please explain why VW did that!

[TylerDurden]

The design envelope was probably 10-15 yrs.

The flow image is from not quite overhead.

Here is an overhead sketch of the heater section & core.

Core is yellow, doors are black and pivot on the circles.

Doors are shown full-cold, vents only.
Dashed lines indicate doors in full-hot, def/floor


I have heard of masochistic folks getting the airbox out without the dash, but hoooooo..... can't be easy.

One note about taping the doors: I added 6mm tape overhangs, like door-sweeps, since the metal doors are slightly smaller than the openings.

[scrounger]

Thanks much for the detailed diagram.
I am pretty sure that the problem in my car is mainly in that top door. Perhaps it is holey. Is the top door controlled by the slide lever for heat?

The heater gets warmer when the the heat lever is over at hot.

I can feel the bottom door vacuum solenoid moving when I adjust it. But the panel vents are always blowing hard and the top and bottom vents are fairly weak.

[TylerDurden]

Yeah, the temp-blend door is controlled the cable.  (I wish they were all cable control, like the Audi 90 & Audi Cabriolet. )

The core adds a bit of restriction, so if you don't have a noticeable air-volume drop when full-hot, the door foam is likely shot.

Constant dash flow would indicate bad foam on the front door.

[scrounger]

Thanks for letting me learn more about the operation of the heater. Hope that the original poster is ok with it.

[R.O.R-2.0]

Jeremy:
Looks pretty cashy. Must be a pretty common tool then?

CHEAP...

BTW, only the non-a/c cars had a cable that controlled the blend door position..

the a/c cars were vacuum controlled..

[TylerDurden]

 

BTW, only the non-a/c cars had a cable that controlled the blend door position.. the a/c cars were vacuum controlled..

Mk1, MK2 AC has vac-control on outlets (dash, def., etc), but temp is cable.

[scrounger]

Mine is an ex AC car. What does the heat cable do?

[R.O.R-2.0]

I think they can be had for under $50. OR close to it, a very very useful tool! I use it in brewing too

just bought one at Sears for $22..

[TylerDurden]

Mine is an ex AC car. What does the heat cable do?

The cable swings the door to send air through or around the core.

Pic of the bottom of the airbox:


The dash ducts are on the far left. The footwell duct has the angled edge.

The vacuum dashpot on the bottom controls the selection of dash vents or footwell/defrost - the blue cable controls the temperature door.

[scrounger]

I can see that solenoid move when I switch positions with the bottom control. Also the cable is moving something. I can feel the drag in the cable pulling and pushing something. There seems to be a lot of air pressure that leaks hot or at least warm air in the seal that is covering the passenger compartment side near the bottom. Are there are any more ideas before just ripping into it?

[TylerDurden]

Here is the thread I ripped a pic from. He cut off the AC lines to get the whole airbox out while the dash remained. (some pix missing)
http://forums.vwvortex.com/showthread.php?2355434-Heater-Core-Time

[92EcoDiesel Jetta]

The design envelope was probably 10-15 yrs.

So VW purposely put holes in the doors, covered them with foam that lasts 15 years then fall apart. Sweet! All they had to do was use a door with no holes, and we wouldn't be having these problems.

[TylerDurden]

Gotta reduce weight everywhere... these are performance machines, doncha-know. 


Seriously, somebody must have had a reason, even half-baked. Beats me.