Fridge runs on propane but doesn’t cool

[strawman]

Hey guys
I’ve just finished removing my fridge and going through all the service steps.
- clean burner box and intake and exhaust tubes
- clean jet
- blew out propane tube into fire box
- cleaned drain tube under the fridge

Fridge works on AC, gets nice and cold. This tells me the cooling system is working.
Propane lights and burner box and exhaust tube get too hot to touch but does not cool fridge at all. Is there something different mechanically between the AC and propane that won’t allow the fridge to cool on propane?

I’ve read so many fridge threads but am yet to find one that answers my question.

I’m bench testing the fridge with a barbecue tank with this regulator.
Gas-flow 800
“Based on 25 PSIG inlet pressure and 9” W.C. outlet pressure at manufacturers set point. Manufacturers set point =100 PSIG and 11” W.C.”

Thanks so much for your help
Cheers
Dan

[crazyvwvanman]

The fridge has 2 burner flame sizes.
Maybe yours is staying in pilot flame, idling mode.
The thermostat setting is supposed to trigger full flame mode.
There is only the 2 flame sizes and you need the full size for much cooling to happen.
The control valve should cycle the flame size between pilot and full depending on temps and setting of thermostat.

Mark

[coastdog]

That’s a strange one. It’s the same boiler tube in the sealed ammonia unit that requires heat in all three modes. I agree with Mark that for some reason the flame isn’t big enough to supply the required heat even though the exhaust is hot to touch. Possibly there is a restriction somewhere or the thermostat isn’t turning up all the way.

Bill

[ALIKA T3]

Just a few threads down, same problem:

https://www.thesamba.com/vw/forum/viewtopic.php?t=801663&highlight=ammonia
_________________
Silicone Steering Boots and 930 Cv boots for sale in the classifieds.
Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

[DanHoug]

heat is heat, so if it works on AC, it'll work on propane IF the propane side is correct. so:

- inlet pressure must be 11" W.C.

- burner jet must be clean. remove, soak in 91% isopropyl overnite, ultrasonically clean for an hour in detergent. odorant and combustion residue neck down the orifice in the jet, it can be stubborn to clean out. they make pilot jet reamers that DO remove the deposit but it is awful easy to over-enlarge the jet (BTDT).

- thermostat must switch flame size between pilot and high.
_________________
-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[strawman]

I soaked the jet in lacquer thinner for about 36 hours. I blew it out with compressed air and I could see light through it.

I’ll try an experiment:
I bought an older Dometic fridge as a spare. I’ve never tested it on propane. It does run on AC. I’ll hook it up to the same bottle and regulator I’m using to test the above fridge and see what happens.
If it cools down then I should be able to eliminate the regulator as a problem. Correct?

The above fridge is a 91 and the spare is 82ish.

When turning the thermostat dial on the 91 from low to high there is a click around the 7 o’clock position. Turning it back down there is a click around the 4:30 position.

On the 82 turning it up it clicks a 4 o’clock then turning it down it clicks at 3 o’clock.

I’m thinking that even with hearing the clicking that doesn’t necessarily mean the flame is kicking into high. Correct?

I’ll do my experiment today and we’ll see what happens. I’ll let you guys know. Thanks.

[Ahwahnee]

Asking because I really don't know...

Is it possible to observe through the sight glass the change from pilot flame to operating flame?

[DanHoug]

[Braukuche]

[strawman]

The experiment was a success. The 82 fridge I bought as a spare works on the barbecue/regulator setup. 15 minutes after light up I casually put my hand on the burner box to see if it was hot. Holy crap, not a good idea, so frikking hot. The 91 burner box doesn’t even come close to getting that hot. After 45 minutes fridge was nice and cold.

I refired up the 91 and after 2 hours I could hold my hand comfortably on the burner box. So I better start with revisiting the propane jet. I have 99% isopropyl alcohol I can soak it in. I’m sure I can go online and find jet cleaning tools. What size am I looking for?

If it’s not the jet, then I presume the next step to look at the controls on top of the fridge. Any ideas around that would be appreciated.

I also have a 1982 air cooled that I’ve just listed for sale. When testing the propane fridge I definitely could hear a reduction in flame size when I turned it down to the low setting.

[DanHoug]

[strawman]

Thanks Dan
I just ordered the tool you recommended, thank you very much. Regarding using the tool, do you twist it as you push it? I see it has a range of .003 to .013. I haven’t seen the tool yet so I’m not sure how long the taper is. Do I run it the complete length of the taper right up to the .013? And do I only do this once?

[DanHoug]

[coastdog]

On your 91 fridge is that a distinct click at the 7 o’clock position? There isn’t meant to be a click there. Sometimes at the very lowest 3 o’clock position you can feel a small detent as that’s where the rotary switch is designed to turn off the 110v. The thermostat controls propane and 110v but not 12v.

Bill

[strawman]

Hey Bill
I just rechecked the thermostat and I was wrong in the post you’re referring to.
Starting from 3:00 the first click is at 11:00 then on the way down from max the second click is at 8:00

[coastdog]

There’s a chance that your thermostat isn’t opening up to full. Some of them do get notchy after 30-40 years. You could switch it out with your early model fridge’s thermostat.

Working on many fridges I’ve only seen one gas nozzle that was bad but it does happen.

Bill

[jpbarnes]

I'm in the same boat...in fact, that was my post referenced above. Fridge runs normally on 110v, but creeps up to 60 degrees when switched over to propane.
One thing I noticed was that my fan on the back was toast. I replaced it with a 2" muffin fan, quickly learn the fan will only ever operate on LP and 12V, but unfortunately, the fridge still only cooled to about 60 degrees on LP. Am wondering now if it's the thermostat or not? I too cleaned the jet, combustion chamber, etc etc.

Any advice appreciated

[strawman]

I’m seriously thinking of doing what Bill has suggested. That swapping out the thermostat. The only thing I’m not really clear about is how to remove what looks like a sensor from the back of the fridge. Looks to me like I can just peel off the sealant and hopefully that sensor just pulls out. I’ve been quite busy lately getting another van ready to be sold so I haven’t spent any time on the fridge. Good news is the van sold to the first person that looked at it. I’m reluctant to try and clean the jet with a tool until I have tried This swap.

Hopefully, I’ll get to it in the next week or so and then I can get back to this form to let you know how it went.
Cheers
Dan

[DanHoug]

[strawman]

Thanks Dan
I really appreciate your advice. Yes I was definitely concerned about the jet cleaning. The tool came in yesterday and I’m feeling better about using it.
Cheers