Date: Mon, 9 Aug 1999 18:40:06 -0400
Reply-To: David Beierl <synergx@IBM.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <synergx@IBM.NET>
Subject: Re: fridge - no run on 12v, gas :-(
In-Reply-To: <f897613d.24e089f4@aol.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed
At 15:45 8/9/99 -0400, Douglas Prescott wrote:
>Refrigerator runs OK on shore power, but I can't get it to run on 12V. Gas
>is another issue (I guess), and I'll figure that out using info from the
>archives (hopefully).
>I'm sure I've had the refrigerator working off the battery in the past, but
>no go this time around. I tried replacing the fuses behind the seat,
>fiddling with different temp settings, etc, to no avail. Any ideas?
Don't bother with the thermostat, 12v is constant-on.
Test for 12v at the plug (in the van) with engine running -- if the relay
under the seat isn't working you get no juice to run the reefer. In that
case if you hook the unit up on the bench it should work. Make sure you
have the right wire -- the 12v should go away when the engine stops turning.
If you have an ohmmeter, test across the 12v input terminals. Resistance
should be in the neighborhood of one ohm. If it is, hook it up and look
for current draw of around 7.5 amps. If this is correct, your heater is
working ok -- open up the sleeve around the boiler and put the heater
element back in the sleeve welded to the boiler, just like the 110v
one. There's a screw at the bottom to secure the element.
If open circuit or high resistance, follow the circuit around until you
find the trouble (probably the switch or a wire unplugged, maybe the
$$$heater element$$$. The 12v circuit is very simple, all there is is a
switch and a heater.
>I've cleaned the burn box and everything else in and around it and the whole
>unit to try to get the gas to work, but no luck there either.
Here are some thoughts on gas troubleshooting:
First of all, if you're going to be plugged in at night, you have a
fallback position: Get an inverter of at least 100 watts capacity (Radio
Shack has them but $$$ -- try West Marine, Sams, FLAPS etc -- 150 watt
should be available $50 or less). Plug the fridge into the inverter and
run it on AC position all the time. Just remember that you have strictly
limited running time without the motor running, and unless you have a
ten-amp charger hooked up as I do, you will have to shift the fridge plug
to "real" AC.
You could also jumper the relay to allow the DC side to run with the motor
off, but I recommend the other route b/c thanks to the nature of
electricity and to VW's marginal wiring, it's going to run better on
AC. Also the inverter will shut down before the battery is completely
dead, which gives you a fighting chance.
My questions:
#1 can I bench test this with my barbeque propane w/o a dc hook-up?
You don't need any DC for propane operation. My suggestions for checking:
1) Install van regulator on BBQ tank.
2) Check regulator outlet pressure and adjust if needed.
3) Remove mounting screws from burner pan and rotate/move it partially
clear of the flue ass'y. Make sure you don't disturb the burner tube.
4) Shelter the setup from any wind. Hook up propane direct to the nipple on
the burner pan (as I recall, 7mm fuel hose is a tight screw fit onto that
nipple). Turn it on and light the burner with a match. At this point you
should be looking at a quiet, clear blue flame with the thermocouple
touching it and the spark terminal glowing dull red right in the middle of
it. In the dark the flame is about an inch and a half high. If not,
you're looking at an orifice problem.
5) Blow it out and light it with the spark. I'm pretty sure it's grounded
through the thermocouple but if the pan bites you when you hold it then a
jumper wire would be a good idea... <g>. Results should be ditto. If not,
adjust spark electrode as needed until it lights. Electrode *should* be
right over the middle of the slits in the burner tube. Observe where the
spark lands -- I'd expect on the upper surface of the burner tube, but
don't know for sure.
6) Hook up the proper gas fitting to the burner again, and hook the propane
to the reefer inlet. Now open the gas valve on the reefer, set thermostat
to max, press the safety button and light the burner with match or
spark. Be persistent, the system may be full of air. If no
light, there's a problem with the safety valve (or a crimped tube
somewhere) -- make sure button is pushed in all the way and that nothing is
interfering with it. If it does light, wait 30 secs and let go of the
button. If the flame goes out, likely a thermocouple problem.
7) The flame in 6) should be the same size as when it was hooked direct to
the bottle. If not, there's a thermostat problem (probably). Now turn the
thermostat to minimum. The flame should get much smaller (don't know exact
size).
8) If all the above work, the system is basically ok. Offer the pan up to
the top plate and secure it with a couple of screws at corners (don't need
gasket). Get a tiny mirror and observe through the little window while
someone tries to light it. If it lights, cool. If it doesn't, see where
the spark is going. Could it be jumping to the top plate instead of the
burner tube (or is it the thermocouple? I haven't noticed b/c I've never
had trouble getting it to *light*). If the spark is the same as before
then I would strongly suspect the air pump which shoves a bit of air down
the inlet to keep propane from puddling and filling up the burner
pan. Might try mouth-blowing on the tube. Also remove burner pan and make
darn sure that inlet and flue are completely open. I used a refrigerator
coil brush (which also had a handle of exactly the right diameter to shove
into the top of the flue and bend it into the right position to remount the
outside hardware -- it has to be almost exact by itself, the outside stuff
can't exert much force without distorting, stripping screws, whatever).
9) When all above is solved and happy, remount the burner pan with gasket
and screws. If necessary supplement or replace gasket with high-temp RTV
silicone. Try it one more time to be sure...
#2 How much air should I be able to blow through the orifice
using my breath? It must be a tiny hole based on how little I can
blow.
It is a tiny hole indeed. Unscrew it, soak it in alcohol then blow it out
with compressed air. Don't even think harsh thoughts at it, let alone
touch it with anything.
#3 Which way do the fans blow air...up or down? My Dometic fan
is mounted on the bottom of the bracket and appears to blow
down. Again,
no dc for bench test.
All fans blow up (so stay clear of flying fragments <g>). Hook it across
your vehicle battery to verify which way it thinks is up (L-bracket should
have motor above bracket, strip bracket should have motor below, I believe).
#4 If it does blow down, why? Heat rises, wouldn't it make more sense to
blow air out through the top?
If it does blow down it's b/c it's hooked up backwards. *Speaking of
which* note that the *brown* wire to the fan thermostat is *HOT*, unlike
every other brown wire in Germany!
#5 Does that tube that runs through the back of the fridge (that
I'm trying to avoid screwing into) go straight across the back
or diagonally?
#6 I read the debates. Which is best wiring for the extra fan: series or
parallel? Seems like parallel but would like confirmation. I have
Bulley's pictures for help :-)
Every electrical device in the van (speaking broadly) is wired in parallel
with every other. Ditto your house. This is no exception.
#7 Do I need to burp it now that its laid on its side during servicing?
No but it can't hurt. Invert several times (per Dometic service
bulletin). Regardless, immediately before installing, tilt to right and
left, forward and back a few times to equalize things.
I haven't done a pressure test with it yet as I pulled the dometic before I
realized that I should have checked the pressure first then pull the unit
(rookie mistakes)
There is supposed to be a pressure test port on the fridge itself, which is
the best place to test. But of course you can't get to it with the fridge
installed. Possibly with the front off. Any way, you can simply mount the
regulator on your BBQ tank and work from there.
cheers and don't hesitate to call -- 401 274-5827
david
David Beierl - dbeierl@ibm.net
