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1973vwthing Samba Member
Joined: April 21, 2006 Posts: 108
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Posted: Tue Feb 26, 2008 4:16 pm Post subject: heater question...cold out!! |
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the bn4 gas heater in my thing turns on for about 20 seconds or so gets warm then shuts down...no fan or anyhting...if i wait about 10 minutes it will fire back up and do same thing...not blowing fuse or tripping safety switch...any siggestions?...been reading bunch of posts...thanks everyone!!... |
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mrafindley Samba Member

Joined: December 29, 2007 Posts: 642 Location: miami Florida
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1973vwthing Samba Member
Joined: April 21, 2006 Posts: 108
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Posted: Tue Feb 26, 2008 8:16 pm Post subject: |
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think the fan motor heats up and shuts down?....after heater shuts down i can see some smoke inside the front wheel well...then goes away after a bit...the fan seems to blow fine if gas isn't hooked up and can't fire up the fuel...any more ideas...reading thru manuals...thanks again |
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1973vwthing Samba Member
Joined: April 21, 2006 Posts: 108
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Posted: Tue Feb 26, 2008 8:16 pm Post subject: |
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think the fan motor heats up and shuts down?....after heater shuts down i can see some smoke inside the front wheel well...then goes away after a bit...the fan seems to blow fine if gas isn't hooked up and can't fire up the fuel...any more ideas...reading thru manuals...thanks again |
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mrafindley Samba Member

Joined: December 29, 2007 Posts: 642 Location: miami Florida
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Posted: Tue Feb 26, 2008 8:22 pm Post subject: |
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The smoke is there because the exhaust pipe for the heater is there sounds like to me the thermostat pull and push the temp knob the cotacts could be stuck _________________ 73 THING
67 Beetle
http://w2.wolfsburgii.com/downloads.htm |
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1973vwthing Samba Member
Joined: April 21, 2006 Posts: 108
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Posted: Tue Feb 26, 2008 10:10 pm Post subject: |
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i bypassed the push pull thermostat by putting the 2 blue wires that run to it together...the heater stayed on and when i switched the power knob off the pump stopped clicking but the fan kept running for a bit(to clear exhaust gases?) then shut off on it's own....is it bad to run heater like this?....how hot should it get if thermostat is bypassed...i only ran it for 5 minutes or so....thanks again!!1 |
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crofty Judas of the North

Joined: August 09, 2000 Posts: 19760 Location: Land of Whine and Phonies
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Posted: Tue Feb 26, 2008 10:41 pm Post subject: |
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Before you start playing with a gas heater buy yourself a manual. The thing shop has them and they are worth the investment _________________ Your Vanagon sucks, Stop waving at me.
HamburgerBrad wrote: |
I slept on crofty's tent once. I passed out drunk from two bottles of Everett's brother's wine. |
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1973vwthing Samba Member
Joined: April 21, 2006 Posts: 108
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Posted: Tue Feb 26, 2008 11:32 pm Post subject: |
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have manual but doesn't discuss adjusting thermostat...i can see things in the thermostat rotating when i push and pull....since heater runs and doesn't shut off when bypassing thermostat is the thermostat the problem or could it be further down the line...also, the fan goes thru the run-on cylce with thermostat bypassed...thanks everyone!! |
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Ray Syverson Samba Member
Joined: February 12, 2006 Posts: 74 Location: Lake Zurich, Illinois
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Posted: Wed Feb 27, 2008 6:04 pm Post subject: heater question--cold out! |
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I have a 73 Thing and have recently been reading my manual and playing with the thermostat switch.It sounds your problem may be with the thermostat switch.In the owners manual it says to pull the heat control knob out before starting the heater.In the heater manual it says to pull the knob out before checking the thermo switch.Why? Maybe in some cases the contact points are open in the switch when the heater is cold.They need to be closed for the heater to start(you closed the circuit by putting the wires together and the heater ran)By pulling the knob out before you start you cause the contacts to close if they aren't already.I've heard that the thermostat switch is trouble prone.The heater manual shows two types.The one I have mounts on the top of the hot air duct and can easily be removed with two screws after disconecting the cable.It has two stop screws that limit travel of the push-pull and also another adjustment down by the spring underneath. I would suggest you try starting the heater with the knob pulled out (blue wires back on) and see if that works. Then whether it does or not take off the thermostat switch if you can and inspect it. If its like the one I have you can blow hot air on it with a heat gun or hair drier and see the contacts open and close and you should see how to adjust it.You can clean contacts and check operation with an ohmmeter or tester lite.If you can try to get it tweaked a little so that when the lever is pushed the way it is when the control knob is pushed in,the contacts are closed.If the heater didn't start with the knob pulled out, perhaps cleaning those contacts will help.If the thermo swich seems different than what I've described then you may have the more difficult one that I don't know about.
The thermostat switch controls the heat by turning off the current to the fuel pump when the air gets too hot. when it cools down it swiches on again. Without the switch(your bypass) the heater can get too hot and blow that fuse thats on top of the heater.Hope this helps --at least something to try. I'd definately suggest getting that manual from The Thing Shop though. Ray |
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dan macmillan Samba Member

Joined: October 19, 2003 Posts: 3110 Location: Northern Ontario, Canada
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Posted: Wed Feb 27, 2008 7:43 pm Post subject: |
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1973vwthing wrote: |
i bypassed the push pull thermostat by putting the 2 blue wires that run to it together...the heater stayed on and when i switched the power knob off the pump stopped clicking but the fan kept running for a bit(to clear exhaust gases?) then shut off on it's own....is it bad to run heater like this?....how hot should it get if thermostat is bypassed...i only ran it for 5 minutes or so....thanks again!!1 |
This is normal operation. If you listen closely it will spin slowly at first. When it gets to a set temp the blower will speed up. If you turn it off when running slow it will stop instantly. If it is at normal operating temp and spinning fast, it will run on after turned off to cool the inner chamber.
Not a good idea to bypass the stat other than to test it. It will eventually get hot enough to trip the reset and shut down. _________________ Licensed Automotive Service Technician
Licensed Truck and Coach Technician
Licensed Heavy Duty Equipment Technician
CFC/HCFC/HFC A/C handling and installation license
Alignment specialist
66 Modified Manx,68 Kyote,74 Thing,74 Beetle, 76 Transporter,75 self made Double Cab,65 Meyers Manx,78Westy,68 Ghia, 79 Bradley GT2
Current projects:
Built for others:69 Manx Clone |
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1973vwthing Samba Member
Joined: April 21, 2006 Posts: 108
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Posted: Thu Feb 28, 2008 1:01 am Post subject: |
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thanks for the replies... i have the square type thermostat that pushes in and sits in the heater duct just before it entoers firewall...i will try different adjustments on thermostat...the heater fuel pump is acting up...works fine for a bit then stops i hit it then it starts again and so on...probably on its way out?...any way to get it apart?..it's the later style straight pump.....thanks again everyone!!! |
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crofty Judas of the North

Joined: August 09, 2000 Posts: 19760 Location: Land of Whine and Phonies
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Posted: Thu Feb 28, 2008 8:32 am Post subject: |
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Try cleaning the points in the fan motor. It's those points that cause the pump to pulse and the plug to fire. _________________ Your Vanagon sucks, Stop waving at me.
HamburgerBrad wrote: |
I slept on crofty's tent once. I passed out drunk from two bottles of Everett's brother's wine. |
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1973vwthing Samba Member
Joined: April 21, 2006 Posts: 108
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Posted: Thu Feb 28, 2008 4:01 pm Post subject: |
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i can read voltage jumping up and down on the wires going to the pump...probably pump is on its way out? |
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1973vwthing Samba Member
Joined: April 21, 2006 Posts: 108
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Posted: Sun Mar 02, 2008 10:10 pm Post subject: |
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got heater fuel pump working...just stuck...i made some adjustments to the thermostat and seems better...wondering how long heater should run before thermostat shuts it down...what is the proper position of the little white plastic cam that hits the contact to shut heater down?(this seems to be my problem) how do you adjust thermostat to stay on longer? manual doesn't cover this...thanks again!!! |
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crofty Judas of the North

Joined: August 09, 2000 Posts: 19760 Location: Land of Whine and Phonies
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Posted: Tue Mar 04, 2008 8:57 am Post subject: |
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Run on is around 2 minutes. It's mentioned in the manual. _________________ Your Vanagon sucks, Stop waving at me.
HamburgerBrad wrote: |
I slept on crofty's tent once. I passed out drunk from two bottles of Everett's brother's wine. |
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Ray Syverson Samba Member
Joined: February 12, 2006 Posts: 74 Location: Lake Zurich, Illinois
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Posted: Tue Mar 04, 2008 3:03 pm Post subject: |
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There is a temperature range that the thermostat is supposed to keep the heat at (something like 120-150 degrees,I dont have my manual here).After adjusting the thermostat switch on my heater I ran it and held my hand under the outlet under the dash. It seemed to be a bit less hot than before and that was what I was after.I could feel the temp drop down slightly when the thermo switch opened and then rise again when it closed.When you shut the heater off it should cntinue blowing for awhile till the temperature comes down ,then shut off completely. |
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Woreign Samba Member

Joined: June 04, 2006 Posts: 2841 Location: Crestview FL
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Posted: Tue Mar 04, 2008 8:57 pm Post subject: |
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You can safely adjust the thermostat to 212 degrees by placing it in boiling water. When the thermostat has opened (twisted) completely, adjust the plastic cam so that it just interrupts the switch. I did this on my heater and it works very well. Any hotter and the built in safety circuit will trip. I think it trips around 265 or something.
If you're having run-on issues, you may need to adjust the flame sensor. It is located on the back-left side of the heater (facing the open trunk). It adjusts with a flat blade screw driver. If it the fan won't shut off, turn the screw until it does. |
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Ian Epperson Samba Member

Joined: January 12, 2005 Posts: 2262 Location: Alameda, CA
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Posted: Tue Mar 04, 2008 10:17 pm Post subject: |
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1973vwthing wrote: |
i can read voltage jumping up and down on the wires going to the pump...probably pump is on its way out? |
As you may have figured out, that's normal operation. Those pumps are pretty indestructible, but if you let them sit idle for more than a month or two, they'll start to freeze up - a good cleaning and/or hitting them and running them will free them up again.
1973vwthing wrote: |
i bypassed the push pull thermostat by putting the 2 blue wires that run to it together...the heater stayed on and when i switched the power knob off the pump stopped clicking but the fan kept running for a bit(to clear exhaust gases?) then shut off on it's own....is it bad to run heater like this?....how hot should it get if thermostat is bypassed...i only ran it for 5 minutes or so....thanks again!! |
Once you do this, the heater will run until it blows the overtemp fuse. If that fuse doesn't blow at 300 degrees (or so), then that particular safety feature isn't working properly. Did someone swap out the 8 amp fuse with something bigger? When it trips, it shorts out the circuit and intentionally blows - which can be disconcerting and make you think you need a bigger fuse.
The thermostat is supposed to prevent it from getting so hot that the fuse blows. Since it kept cooling off, it sounds like your thermostat was at least functional - it may have been wedged into a low temperature or something, but at least it was turning off the heater appropriately. _________________ VW-181 shirts and stickers.
http://ian.epperson.com/vw |
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1973vwthing Samba Member
Joined: April 21, 2006 Posts: 108
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Posted: Wed Mar 05, 2008 9:05 am Post subject: |
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i belive everything is in working order according to manual...it's just getting the square thermostat that sits on the heater adjusted right...gonna fiddle with it more...thanks for the responses!!! |
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1973vwthing Samba Member
Joined: April 21, 2006 Posts: 108
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Posted: Thu Mar 06, 2008 7:00 pm Post subject: |
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does anyone know if the little metal piece that the plastic cam in thermostat touches (square kind mounted on duct going into firewall) is supposed to separate from one of the contacts...or what type of movement does this little metal strip make when the plastic cam hits it...not sure if it's this metal strip that is out of wack...i think this is my problem...hope this makes sense...thanks!!! |
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