Older fridge cooling Better on 110 than propane

[Buffblazer]

Hello all, hoping for some help before my 4th of July trip

I took my 98 Lightcraft truck camper up the mountain this last Friday and when I left the house with the fridge on 110 the temp was 28 degrees.

Switched over to propane and drove an hour to my spot to find the fridge at 55 degrees. Could not get it to cool down.

Yesterday I ran it on 110 to verify it wasn’t the cooling unit. I had a tall blue flame but went ahead and cleaned the burner unit and blew out the area. Still the same height flame.

I adjusted my settings from hi-med-low and see very minimal flame height change and have never heard the propane “roar” that people talk about in the 2 years I have owned it. I did replace my regulator last year and have no issues with my stove or heater working.

Any suggestions? Not sure of the brand of fridge. It’s the old school 3 way with the turn knob in the back and the green 110 switch and red 12v

Thank you

[opnspaces]

A DIY manometer, there are many examples on the net.
Link

[stevemorris]

dougrainer wrote:

Buffblazer wrote:
Ok that makes sense. It was loose so I was wondering if it’s depth in and out of the burner mattered.

So I cleaned everything again, turned on the gas without anything attached to push any debris out of the line and reached up in the chimney and cleaned what I could.

Turned it on with the fans at 7:00 at a fridge temp of 80 and at 9:00 it was 55 ( I know I shouldn’t have opened it but I was curious) I shut off the fans and this morning it was at 25 degree. So that made me super happy. I kicked on the fans and will check it again tonight after a 85 degree day.

So, with NO fans, the refer got down to 25 degrees? If so, WHY would you operate the Fans? Remember, the point of refer convection is to flow air thru the Condensor fins, REMOVE the heat and flow out the upper vent. IF you force the air thru those fins TOO FAST, they will not remove the heat. So, maybe you have to fast air flow. Doug

rubbish!!the faster the air flow the better the heat transfer and a better cooling fridge

[ajriding]

philh wrote:

ajriding wrote:
Im not disagreeing, I just saying more airflow will cool the fins faster…
What can happen with wrong fan placement is that the air gets turbulent and does not do a good job flowing through the fins.

Flow too fast, there's not enough time for heat transfer. HOWEVER, in our fridges, they depend entirely on convection for heat transfer. A fan can help increase the flow.

another guy: the cold output temp on Lo fan then med fan then hi fan. You will notice on LO fan, the output is COLDER. Because,

You guys are so out there….
This is not a car AC but similar principals apply. You observation is correct, however your conclusion is wrong. The reason the temp is cooler on low than high is that you are removing a fixed amount of heat (cold) from the evaporator in your dash. The amount of cold coming out, no matter the speed, is actually the same, but by speeding up the air you get more warm air mixed in with the cold.
Actually the higher speed air will put more cold into the car than the slow, even though the slow measures a lower temp. If you put one gallon of 40 degree air into a 80 deg car that wont do much, even though it is cold, but put 10 gallons of 45 degree air in and you will see a difference in car temp. The gallons represent speed. one gallon is slow, 10 is fast.
The faster the air flows the more cool the car becomes. You can raise the speed and this stays true up to the point that the air movement is making too much heat from friction and overtakes the amount the AC compressor can cool. At very high air speeds the fins might feel the same temp as the incoming air.
In your fridge the hotter the fins feel then the less the air is pulling heat from them. Faster airflow will pull more heat. Air molecules do not need "time" to pull heat.
Inside the AC system the airflow is heating up the coolant (134r or freon), and the faster (more) air that contacts the fins the more heat is transferred (up to the point ,at sonic, speeds the air will create heat friction).
This also works up front at the grill where the condenser is, it sits in front of the motor radiator, and both need airflow to work, this is why there is a fan there. The faster the air flows, the more cooling the radiator and condenser will cool the contained liquid and gases.

Higher airflow will cool the refrig fins better, but in reality only a little airflow is needed for the fridge to function, this is why so many people use the tiny computer fans.

[JRscooby]

dougrainer wrote:


The ONLY way to test LP pressure is with a Manometer. Buying one for $60 is cheaper than paying your Local RV dealer to do a Manometer check

But AFAIK, no mater what you pay for a Manometer you must make a gas tight seal to the line. I used a clear plastic line that fit tight on the flare. Left the line long, tied up to top of lower opening, (above the valve) drop down, ran across ground a couple feet, then loosely zip tied to a yardstick. Put enough water in the tube to fill it for a couple of feet. Hold the stick verticale, and slide it until water level is on a mark, and tighten the ties so it stays put. Turn on the gas, if the water line goes up 11.5 inches, your good.

[philh]

ajriding wrote:
Im not disagreeing, I just saying more airflow will cool the fins faster…
What can happen with wrong fan placement is that the air gets turbulent and does not do a good job flowing through the fins.

Flow too fast, there's not enough time for heat transfer. HOWEVER, in our fridges, they depend entirely on convection for heat transfer. A fan can help increase the flow.

[NRALIFR]

This and other models are available.

Amazon: Digital Manometer

:):)

[dougrainer]

Buffblazer wrote:
Scooby: thanks for the advice, I think I will have to do that mod myself.

Doug: is there a way to test the LP pressure from home? Or do I need to take it in to the dealer?

Checked it this morning, temp was at 55 with no fans running. So Monday it was 80 during the day, cooled to 25 that night, over 80 that evening and now is at 55. The fluctuation is confusing me.

The ONLY way to test LP pressure is with a Manometer. Buying one for $60 is cheaper than paying your Local RV dealer to do a Manometer check

[dougrainer]

ajriding wrote:

dougrainer wrote:
IF you force the air thru those fins TOO FAST, they will not remove the heat. So, maybe you have to fast air flow. Doug

Umm, never heard that one before….
Every other finned cooler (lawnmowers, motorcycles, electronics etc) cools better with faster air, Im not disagreeing, I just saying more airflow will cool the fins faster…
What can happen with wrong fan placement is that the air gets turbulent and does not do a good job flowing through the fins.

Odd that your fridge does this. I am not an expert on where the AC heating element is in relation to the flame.
Most common is when fridges are run out of level they quit working slowly. What happens is the chemicals get trapped in the coils and stuff burns and cakes up like concrete down at the burner bulb. I am wondering if you have some cooked stuff above the flame, but wherever the AC element is maybe not as much cooked stuff, thus is able to get the heat into the system better.

The temp solution is to remove fridge, turn upside down so the burnt stuff moves out of the way so the heat can do its job. This solution does not last forever, but buys you time.

If you have a decent size flame then it should be cooling better just 55. It should be a little bigger than a candle flame at least.

I have hears sounds from the fridge, but only at night when it is dead quiet. A roar is common from a boiler, but not a fridge, but the fridge sound is amplified through the chimney - its a roar sound, but not a loud one by any means.

Fas are good, but I dont think they address your situation given it works so well on AC.

If the fridge side is in direct sunlight then it will be hard to cool it. Eliminate this as a variable from AC to propane.

Simple test Technicians use it when testing AC's. Get in your car and turn on the Dash AC. Then using a digital Thermometer, note the cold output temp on Lo fan then med fan then hi fan. You will notice on LO fan, the output is COLDER. Because, the air moves over the evap fins slower and has time to absorb more cold. Same principle on removing heat on a CONVECTION type Condensor. Now, on a Car Radiator, the more air flow it will remove heat better. Doug

'PS. The Blockage of a cooling unit is no where near the burner . It is between the freezer and lower section coil. Burping will just be a temporary fix.

[ajriding]

dougrainer wrote:
IF you force the air thru those fins TOO FAST, they will not remove the heat. So, maybe you have to fast air flow. Doug

Umm, never heard that one before….
Every other finned cooler (lawnmowers, motorcycles, electronics etc) cools better with faster air, Im not disagreeing, I just saying more airflow will cool the fins faster…
What can happen with wrong fan placement is that the air gets turbulent and does not do a good job flowing through the fins.

Odd that your fridge does this. I am not an expert on where the AC heating element is in relation to the flame.
Most common is when fridges are run out of level they quit working slowly. What happens is the chemicals get trapped in the coils and stuff burns and cakes up like concrete down at the burner bulb. I am wondering if you have some cooked stuff above the flame, but wherever the AC element is maybe not as much cooked stuff, thus is able to get the heat into the system better.

The temp solution is to remove fridge, turn upside down so the burnt stuff moves out of the way so the heat can do its job. This solution does not last forever, but buys you time.

If you have a decent size flame then it should be cooling better just 55. It should be a little bigger than a candle flame at least.

I have hears sounds from the fridge, but only at night when it is dead quiet. A roar is common from a boiler, but not a fridge, but the fridge sound is amplified through the chimney - its a roar sound, but not a loud one by any means.

Fas are good, but I dont think they address your situation given it works so well on AC.

If the fridge side is in direct sunlight then it will be hard to cool it. Eliminate this as a variable from AC to propane.

[Buffblazer]

Scooby: thanks for the advice, I think I will have to do that mod myself.

Doug: is there a way to test the LP pressure from home? Or do I need to take it in to the dealer?

Checked it this morning, temp was at 55 with no fans running. So Monday it was 80 during the day, cooled to 25 that night, over 80 that evening and now is at 55. The fluctuation is confusing me.

[dougrainer]

Buffblazer wrote:
I usually run the fans when the temp is over 80 and in direct sunlight and turn them off at night. Been kind of trial and error to see how much they help or not.

Started off at 25 at 5:30 this morning and the gauge was over 85 when I got home at 6:00. Fans ran all day.

As for the fins, are you talking about the ones that are about half way up the fridge? If so, I have a fan that is directly underneath of those pointed up to draw the fresh inlet air up to the exhaust fans.

So that very well could be my issue. That fan is point blank blowing air over those fins. I went ahead and disconnected it and will see tomorrow when I run the fans for the heat if it makes a difference.

I’m curious though. When I had the camper in the garage when I first installed the fans, I never had an issue with the fridge not staying cold with the fans running, even the one blowing over the fins.

I was on AC power, but that shouldn’t make a difference between propane or AC for the heat on the Fins right?

Regardless of what some think, Running on LP or 120 makes no difference is cooling. The BTU's are designed to get the same output. Now, LINE voltage will make a difference on 120 and LOW LP pressure on LP. LP pressure is critical to correct performance on LP. 10.5 versus 11.5(correct) will yield poor cooling. 10.5 will not be noticeable on Furnace/Range/water heater operation. But will on Reefer LP operation. Below 115 volts will affect 120 operation is higher ambient temps. Doug

[JRscooby]

My fridge is in a '97 model trailer. Over the years I have made it work much better than when I got it.
First I saw the air that came in the bottom vent could go right out the top. Made a baffle (cardboard shaped, then covered with duct tape) from the top of vent to the bottom of fins. This makes all the air go between fins. Then I found the top of cabinet was warm, so made another baffle from top of fins to top of upper vent. This is sloped so the natural rise of the warmer air (heated by fins) is pushed out the vent. Also I used some light gauge of that metal I can't say or spell to help guide the heat from chimney out vent.
I have one of the little fans, but only turn it on if I expect the temps over 100.

[Buffblazer]

I usually run the fans when the temp is over 80 and in direct sunlight and turn them off at night. Been kind of trial and error to see how much they help or not.

Started off at 25 at 5:30 this morning and the gauge was over 85 when I got home at 6:00. Fans ran all day.

As for the fins, are you talking about the ones that are about half way up the fridge? If so, I have a fan that is directly underneath of those pointed up to draw the fresh inlet air up to the exhaust fans.

So that very well could be my issue. That fan is point blank blowing air over those fins. I went ahead and disconnected it and will see tomorrow when I run the fans for the heat if it makes a difference.

I’m curious though. When I had the camper in the garage when I first installed the fans, I never had an issue with the fridge not staying cold with the fans running, even the one blowing over the fins.

I was on AC power, but that shouldn’t make a difference between propane or AC for the heat on the Fins right?

[JRscooby]

Cool a case of water in your home fridge, put it in the camper fridge. Wait a day, then check the temp.
If you are thinking a fridge is misbehaving a indoor outdoor thermometer with a thin wire to the remote sender and a memory is a good idea. Reset it every day, and you know what the high (and low) temp was.
Some people like the wireless kind, but I never got one to read thru wall of fridge. My brother uses one in TV to watch the temp of dorm fridge in TT, and another for the icebox...

[dougrainer]

Buffblazer wrote:
Ok that makes sense. It was loose so I was wondering if it’s depth in and out of the burner mattered.

So I cleaned everything again, turned on the gas without anything attached to push any debris out of the line and reached up in the chimney and cleaned what I could.

Turned it on with the fans at 7:00 at a fridge temp of 80 and at 9:00 it was 55 ( I know I shouldn’t have opened it but I was curious) I shut off the fans and this morning it was at 25 degree. So that made me super happy. I kicked on the fans and will check it again tonight after a 85 degree day.

So, with NO fans, the refer got down to 25 degrees? If so, WHY would you operate the Fans? Remember, the point of refer convection is to flow air thru the Condensor fins, REMOVE the heat and flow out the upper vent. IF you force the air thru those fins TOO FAST, they will not remove the heat. So, maybe you have to fast air flow. Doug