heater box supplied heat

vwfye · Post by **vwfye** » Sun Nov 26, 2006 9:11 pm

i was just reading what i think is the 411 owner's manual. is the 412's heater system/set up the same? the 411 manual says that i am suppose to pull the heat lever only 1/2 way up for max engine suppied heat. then only pull the lever all the way up for use with the gas heater. is this true? if so, that might explain why i am getting a minimal amount of heat. thanks for any help guys!

raygreenwood · Post by **raygreenwood** » Mon Nov 27, 2006 4:47 am

Yes...as far as I remember, they are set up the same. The only differences are in small detail to the wiring and part numbers of the gas heater itself.

The manual is poor in explaination. If you need full air flow, you pull the lever all the way up....even if you have no plan to use the gas heater booster. The full position has dual duty. It opens the flaps in the top of the heatre boxes...just like any other VW. But it is only in the full up position....that the gas heater will be able to operate....and only when you turn the green knob on the dash. Having the heater lever in full up gives much better heat from just the heater boxes...but will not engage the gas heater until you turn the green knob. Ray

vwfye · Post by **vwfye** » Fri Dec 22, 2006 11:14 am

well, i can hear the fan running and a very small amount of air is moving, but other than that, my stock heat system seams to be DOA. not sure why at this point. doesn't seem to be any obstructions... maybe my fan is just weak. dunno...

raygreenwood · Post by **raygreenwood** » Fri Dec 22, 2006 12:39 pm

I fought this fight for a few winters.

Short of actual heat getting to your feet.....sometimes its how to tell what all is running in the system.
Here are some tips.
When the engine is off....and the gas heater is running...you will not actually feel all that much air movement. This is because only the small electric helper fan in teh back is running. Most of teh air is provided by the main cooling fan.

If your heater is running, ....with the engine off...you should hear the small electric fan running under the hood....and also hear the main turbocharger running. This is hard to hear...and sometimes you have to stick your head under the car to be sure.
Also, you should hear teh fuel pump clicking....click, cick, click ,click...about every 2.5 seconds.

Now, if the fan and blower is running....but no fuel pump clicking.....first turn the green knob all the way up. The two wire thermostat down in the heater channel near the fuel pump may be telling the heater timer switch that the set temperature is reached...and therefore giving no fuel.

If this does not help, turn everything off and with a pair of jumper wires...connect the pump straight toth ebattery. You should hear a single click every time you touch the battery posts. If this shows to have a working pump...then the problem may be in the reset switch on the black fuel pump relay. Push teh red switch until you feel it click...and try again.
Still no fuel pump? Then usually it is the points contained in teh end of the blower assembly. Clean both sets of points (one each for fuel pump and ignition).

If you have the fuel pump clicking and both blowers running...but no ignition, you must first disable the fuel pump...remove one wire.....and let the chamber air out by running the fan for 10 minutes. Then remove the glow plug...turn on the system...and hold the plug with a pair of pliers so you can see the coil heating and the spark sparking.

If you are sparking, pumping fuel...and getting no heat from the tailpipe...it is usually fuel taking a while to fill the tube. Without flame the system resets every five minutes or so. So run it for five minutes ...turn off and reset until flame starts. Once teh lines are full...Just running once every two days or so...keeps them full. Ray

Ephry73 · Post by **Ephry73** » Mon Dec 25, 2006 10:55 am

Are the 411 boxes the same length as the Bus ones? Just curious.

E

raygreenwood · Post by **raygreenwood** » Tue Dec 26, 2006 11:25 am

I believe they are. There are some differences in the external sheet metal and some of the buses used the finnd cast aluminum heat sink on the pipes inside. I have heard that the cast aluminum fin assembly blocks a bit of airflow. Ray

vwfye · Post by **vwfye** » Wed Dec 27, 2006 2:19 am

right now my heaterbox supplied air/heat won't even defrost a small peep hole on the windscreen on really moist days. i can't find any obstructions and that fan in the engine bay is definitely running. grrrrrr

Ephry73 · Post by **Ephry73** » Wed Dec 27, 2006 6:56 am

Hmm. I am thinking of going back to my original idea of 99 to run a set of shortened 411 boxes with a BAS header made for them. I know it's not optimal, but it will be a lot better than a Phoenix header. This way I can have some heat in the Ghia, plus, it will sale better with it. I think the original system, when there are no leaks, and the fan is pushing/pulling enough air it can be quite decent. Not enough to get you to undress in the car, but enough to keep the windows from fogging.

The type 1 heater boxes have somewhat less area to "steal" the heat from, and they get the car mildly warm. I am sure recirculating the heat in the cabin, and using "fresh" warm air will be the best.... I still need to draw it up, and of course, do it cheaply.

E

Chris Hobbs · Post by **Chris Hobbs** » Fri Dec 29, 2006 11:10 am

There is another possible obstruction in the heater airflow but it is hard to check. Where the main cooling fan blows air into the heater boxes to warm the cabin, there are hinged metal flaps (hidden) where the heater boxes attach on each side. These flaps are flimsy and are easily dented, bent, or otherwise frozen in a closed position when some careless mechanic works on your engine and has to remove your heater boxes.

After I had engine work done on my 412 a couple years back, I was mystified as to why I had good airflow on the driver's side but now very little on the passenger side. 2 months ago I took off the muffler and heater boxes to do some of my own maintenance work and--voila!--the metal flap on the passenger side had been bent enough to be frozen shut when the mechanic had put the passenger side heater box back on. I straightened it out before (carefully) reassembling the heater boxes myself--problem solved.

You may be able to check for yourself whether your metal flaps are both OK. There is a removeable heater channel piece over the top of each one secured with 2 tinware screws--remove it and you can stick a finger or tool down and plunk the flap to see if it sounds like it is moving freely. Of course, if either flap is frozen you are hosed, because the only way to fix it is to remove the muffler and the heater box!

vwfye · Post by **vwfye** » Fri Jan 12, 2007 4:28 pm

well i'm still not sure if you are saying there is a way to access the top of the heater box from under the car or from in the cab somewhere. today i went under the car and checked the cables for tension... they move freely, but i took some slack out of them and still didn't really get any better air flow. i am stumped... the car is okay for just me as i am warm all the time, but i can't carry my girls in it right now.

wildthings · Post by **wildthings** » Fri Jan 12, 2007 10:23 pm

The flaps Chris is talking about are located just in front of your muffler, where the heater boxes attach to the fan shroud. Hard to check for sure.

vwfye · Post by **vwfye** » Fri Jan 12, 2007 10:30 pm

front is front? i will try and check them tomorrow morning

vwfye · Post by **vwfye** » Sat Jan 27, 2007 7:14 pm

okay, got good air flow into the cab now... but, it still doesn't really get hot... just sort of lukewarm.

also, my heater fuel pump suddenly started wantign to work iwht the switch in the on position (this is a first), but the slight on the switch still doesn't go active. can the pump run if the red reset switch is blown?

wildthings · Post by **wildthings** » Sun Jan 28, 2007 12:42 am

Could be wrong, but I believe the light comes on with the headlight circuit and doesn't have anything to do with the operation of the heater. I don't remember ever seeing the one on my 411 on.

If you are getting fuel and have spark, you should soon be getting heat. You may have to reset the flame timeout switch several times before fuel gets up to the heater.

From experience with both the heaters in Things and the one in my 411, I never turn them on until the engine has run for 15-30 seconds to let battery voltage build up a little after startup. This helps guarentee that you get a good spark and immediate ignition, verses the potential of a wet plug and an eventual timeout.

vwfye · Post by **vwfye** » Sun Jan 28, 2007 3:20 pm

okay.... here is the BIG question for me... how do i know, without taking the entire thing out and sorting/firing it off out of the car, if my system is safe to operate? i'd like to try and fire it off after i clean the glow plug, but i'll freely admit, i'm nervous