When mine did not cool on propane, the thermocouple was bad.

That doesn't surprise me - even with unlimited 12V, the fridge won't
cool much on 12V.  You have to think of it as "buying time" when in
transit (connected to tow vehicle with tow vehicle engine running).

Most people pre-cool the fridge on 120V for 24 hours, then switch to
12V or propane as appropriate.

There are a few things:

* The tubing from the gas valve to the actual burner can attract a
variety of insects/spiders that can partly or completely clog it.
* The burner can be come clogged with an ash-like powder that needs to
be cleaned.
* The fridge coils can become covered with or clogged by debris that
can reduce their efficiency.

All of these are serviceable by someone with reasonable handyman
skills.

Other things that can affect the effectiveness of the fridge:

* The fridge may not stay below 40 deg. F (4.5 deg. C), which is the
key number, if the ambient temperature is too high.  This could become
a problem at anywhere between 85 and 100 deg F (29-38 deg C),
depending on a number of factors.
* The fridge will not work as well if the vent has the sun shining on
it.
* The fridge will gradually loose effectiveness if it is run
significantly out-of-level (4 degrees is usually the max. angle, which
translates to about 4" (10 cm) side-to-side on a pop-up trailer).
This damage is permanent and can not be repaired.  Usually, operating
on the road does NOT contribute to this kind of damage.

Austin

Have you tried it on AC since you got back home?  Or is your "works on AC"
statement an assumption from before your trip?  If it doesn't work on AC
now, you've got a bigger problem.

Not surprising that running it on DC killed your battery.  A gas/electric
fridge cools by heating only (odd concept, I know!)  So, running on DC, it
is just pulling a lot of current to run a heating element.  You'll want to
only use that while on the road...and as someone else has noted, with a
heavy-gauge wire running to it.  The jostling on the road will keep the
refrigerant solution circulating, but if you stop somewhere off-level, be
sure to turn it off, or it will get damaged.  Not sure how quickly
though...been wondering that myself.

How does the flame look?  Strong and blue?  Or lazy and orange?  Look in
from the outside (may have to remove your vent covers since it's a pop-up)
and make sure nothing is obstructing airflow.  An ammonia absorption fridge
works by having a draft of air cooling the coils and fins.  If something has
blocked it up, that will be a problem.  I bought a used travel trailer back
in the spring and in my inspection after purchase, I found insulation had
fallen in at the top cooling fins (the critical ones)!  If that's clear,
check the flue and make sure nothing has blocked it or fallen down inside.
If you pull the fridge out, you should find a blue baffle hanging from the
top of the chimney above where the flame is.  Pull it out and make sure all
is clear down inside.

Let me know what you find and I can try to help from there...

Wesley