Refrig. Heating Up

[rroessler]

Newly purchased 1976 31 ft. Excella 500, slowly learing about it. The refrigerator has been run only on electricity, does a great job, exept not all of the time. In the mornings the temp inside the refrig has gotten to mid-30's, but beginning around noon it rises to the 70's by 5:30 PM or so, then begins dropping. The TT is in the sun all day until 5:30 or so, then is shaded. The refrig. side is out of the sun in the mornings, then in the sun until 5:30 or so. The freezer appears to do a good job, freezing water to ice.

Am wondering if I have a refrigeration system problem, or is it due to being in the sun nearly all day, or something else? Any and all ideas, suggestions, will be greatly appreciated.

[Pahaska]

You should not get that large a swing. Some difference with daytime temps and sun is normal, maybe 10 degrees at the most, but not up in the 70s. My box can hold 45 degrees on the sun side on a 100 degree day and will go down to the thermostat setting of 35 degrees at night.

If you have a roof vent, make sure that it is clear. The box depends on heat rising to move air over the fins. It doesn't take very much to disrupt that gentle flow.

Better yet, go down to Radio Shack or such and buy a 12v muffin fan. Mount it to move air over the finned radiator at the top of the box. Blow upward or outward as appropriate to get a constant stream of cooler air over the fins. On my 2 previous trailers, I mounted surplus fans from a computer recycling place at about $3 each.

My International came with a muffin fan and a temperature sensor mounted on the fridge fins. When the fins get hot, the fan comes on. It stays on all day and I can hear it cycle off and on at night. I think that CW has a similar sensor fan in their catalog.

[davidz71]

Camping World has a solar powered fan that blows across the coils. I've thought about it but am not sure how long the power suppy cord is from the fan unit. My frig. access is on the curbside where the awning is so I would probably have to run the cord up through the vent and on top of the trailer. Anyone purchase one from CW yet and can tell me how long the cord is?

[Inland RV Center, In]

The higher the ambient temperature, the more critical the operation becomes. The freezer compartment must be level. Secondly, it sounds like the reefer burner may need cleaning, in that some heat is available for some cooling, but as the ambient increase, more heat from the burner is required. If the burner and/or oriface is not properly cleaned, a flame will still be there, but it will be at a much reduced temperature, causing the bottom part of the reefer to start warming up. If the burner was very bad, the freezer would also start to warm up during a higher ambient temperature.

Andy
inlandrv.com

[Pahaska]

Andy, he said it has only been run on electricity. Since the heat input is essentially constant on AC, then, IMHO, the problem is more possibly insufficient air flow on the finned radiator.

In my 2003 International AS, I can cause the fridge temp to rise merely by latching the door open. The opened door covers about half of the upper and lower louvers, My unit has a fan, but the fan reflects right back against the opened door. Very poor design by Airstream and I'm looking into a fix for the problem.

[Inland RV Center, In]

John. I gotta quit this 10 day week routine. I don't have an answer for the electrical problem other than the freezer compartment may not be level.

Andy

[uwe]

Hey Andy,

If you work until midnight every day, then you can do 12-14 days a week.
Take it from a guy that knows.
If it wasn't for the Airstream, I'd do 15 days a week.
No seriously - I'll have my so called fridge checked by you, as soon as you have openings in your shop. And teh Armstrog A/C as well. I have the same problems as as the guys in this post. So far it's been ice box time every time we go out. I do run the fridge, but it's just too flimsy for us. Maybe this whole propane fridge thing is just not right for my family. I talked to others on the campground this weekend, and theirs work, but no one is 100% happy with their propane refrigerators. They don't work as well as the ones at home, of course, but how bad is bad? Maybe ours is too small. Do they get better with bigger sizes?
I precision level the thing, with the bubble in the ice box, keep the chute clean, everything, but it just is a marginal refrigerator nonetheless.

[74Tradewind]

Don't give up yet! Your information was quite informative for me.

We just came back from a trip to Tahoe and the lower portion of our old Dometic RM77 got too warm for the nine pounds of ground beef from Costco that was to be dinner the next night for the whole camp. The freezer was perfect but the lower part got warm. I set it to the lowest setting and the burner was on all the time just to keep it at 38Deg. Could it have been the altitude?

I will check the burner again and also the baffle.

Keep up the good work Andy.

Ciao, Brian

[roessler]

With a carpenter's level, found the shelf in the freezer to be about half a bubble off. At various places in the frig it was half a bubble or more off, but in the other direction???

Last night I adjusted the trailer so the freezer shelf is right on. Will see what this afternoon brings, and post back with results.

One thing I'm confused about is the posts that mention a fan blowing over the "fins". Are these on the outside of the unit, or are they the fins inside at the top of the frig? Also, there are no louvers on the side of the trailer for venting when using propane; is there a roof vent for this?

[Pahaska]

Fans inside the box are good, but they do more to make the various parts of the interior consistently cold than they do to lower the overall temperature inside.

The fins I was talking about are at the top back of the refrigerator on the outside. Airflow over these fins is essential to provide cooling. Without a fan, you are dependent on hot air rising to provide a weak draft over the fins; just like the Xmas whirl-a-gigs that rotate over a candle flame. With a good, clear, well-designed vent stack, this usually does the job; however, a small fan improves the efficiency a whole lot. My International came from the factory with a fan installed.

Camping World has several fans in their catalog, inclluding a solar fan. I prefer a 12v fan. It doesn't have to be big or noisy; after all, the airflow you are augmenting is just a gentle breeze. In my last 2 trailers, I used surplus 12v computer fans at about $3 each. Radio Shack has 12v fans. I installed a switch inside the trailer for the fans. Airstream used a temperature sensor on the finned radiator to turn the fan on and off.

The fan should blow upward if there is a roof stack or outward if there is a side vent. In my Scamp, the interior fridge temperature would start down as soon as the fan was turned on. In the International, the fan runs constantly during the day and I can hear it stopping and starting on cool nights. I can freeze everything in the fridge at temperatures in the 90s unless I keep the control set below 2.

[Pahaska]

If there is not an upper side vent, then there must be a roof vent. The AS roof vents I have seen are low and rounded and look kinda like half of a hot dog bun.

Roof vents are much better than side vents in inducing airflow through the fins, however, iit is a lot less obvious when one gets clogged up.

[uwe]

Dear John,

Would it work with the fan blowing up into the vent, or is it better to have the fan mounted near the roof vent sucking the hot air out?
My trailer is a 1971 Tradewind, and it has a plastic vent going up behind the refrigerator that terminates in a large roof vent. I would love to improve the efficiency of my refrigerator by using these little fans. I use them right now for musical equipment cooling.
What value adn size fan did you use? I know that they come in very different cfm and amperage ratings, as well as sizes.
Sharing your knowledge is much appreciated!

[Pahaska]

I have seen the fans used both ways; above the fins in the vent and blowing on the fins from below. My International, which has a side vent, has the fan blowing out through the louvers which is about the same as putting it above the fins with a roof vent. As long as you can insure a steady flow of cooler air over the fins, it should work.

In my old Scamp, I mounted the fan just above the lower louvers, blowing upwards. That worked well. In my TrailManor, there was a manufacturer-supplied fan that drew through a hose from just above the fins. That was there to supply airflow when the trailer was folded, but helped on hot days.

The fan in the International sems to me to be overkill, but it isn't marked as to amperage. One surplus fan out in the workshop just like I used on the Scamp is rated at 2.6W (less than 1/4 amp). I have also tried 2 larger muffin fans in series blowing on the fins from below. The series fans turn slower, but there is more even airflow and no noise. The series fans worked really well and didn't pull much current.

I try to install the fans such that airflow is not impeded too much with the fans off.

[uwe]

Thanks, John.
I will be out searching for suitable 12V fans tomorrow.
The idea with using 2 of them in series sounds good to me.
I am going to try and also pull out the refrigerator completely, to take aclose look at things behind, below and above.

[roessler]

Leveling didn't do anything to improve frig performance, so I guess I'll try fans next.

Question to Pahaska: You mentioned hearing the fans cycle off and on at night. Apparently you have some sort of temperature switch to control them; if so, where and how is it mounted?

[Pahaska]

The switch is mounted on the tubing at the end of the finned radiator at the top rear of the fridge. The AS part number is 690394 "Power ventilator, refrigerator". I assume this is the fan and the sensor since the sensor isn't separately listed.

I'm just as happy with the toggle switch inside the trailer that I had on my previous trailers.