Trailer A/C unit

[BTiner]

Just got back off a hot trip. My A/C unit would run 8-10 hours before starting to recycle. The unit is a ducted 15,000btu Duo-Therm. The RV dealer said it was most likely low on freon. Since the unit is 6 years old he said it would be best to replace it instead of recharging it. Has anyone ever had a unit recharged and if so how long did it last?

 

[scotmartin]

Try testing the temperature differential between the return and supply air. In other words; Make sure that the unit is blowing out air that is twenty degrees colder than the air going in. I would pull off the cover on the roof and make sure that both coils "radiator looking things" are very clean.



To answer your question, it is more an issue of cost than longevity. If it costs $400 to fix a $600 unit, then I would say replace it. But I would look at the unit for cleanliness and air duct leaks before I replaced it.



Scot

 

[B.G. Smith]

AC

Sounds like the evap. is freezing up after running for long period. Could be just lint/dust on coil but is probably low on refrigerant. Two problems with recharge, one, it is probably F-12 and is expensive if you can find it, two, if it is low, then you have a leak and it should be found and repaired if possible. Having said that, if it was mine I would try the recharge first if the price were within reason. bg

 

[BTiner]

Thanks guy's for you help. Last night ( 5:30 pm) I went out to do some testing. The temp was 99 degrees outside and 100 inside the trailer. Turned on the A/C and set the thermostat at 75. Checked the unit at 6:00 pm with a temp probe and the return air was 80 and the discharge was 58, inside temp was 90. Went back out at 7:45 and return temp was 72 , discharge was 50, inside was 78. Went back two hours later and the unit was recycleing. Inside temp was 70 degrees. This tells me that the Thermostat is off 5 degrees and every thing is working OK ( I think ) Am I right or wrong ?

Bill

 

[FParisi]

I had the same question. We got back from a 4,000 mi trip, Ca to Mt and return. Very hot! The trailer took forever to cool off.

I checked the out put temp -53* so I presume everything is OK.

The only other thing I can think of is to check to make sure the ducting is intact - not easy under the floor.

BTW - 32' alfa w/2 slides + 15,000btu dometic.

Frank

 

[The patriot]

Originally posted by BTiner

Thanks guy's for you help. Last night ( 5:30 pm) I went out to do some testing. The temp was 99 degrees outside and 100 inside the trailer. Turned on the A/C and set the thermostat at 75. Checked the unit at 6:00 pm with a temp probe and the return air was 80 and the discharge was 58, inside temp was 90. Went back out at 7:45 and return temp was 72 , discharge was 50, inside was 78. Went back two hours later and the unit was recycleing. Inside temp was 70 degrees. This tells me that the Thermostat is off 5 degrees and every thing is working OK ( I think ) Am I right or wrong ?

Bill

I'm no expert, but it seems like it's doing a decent job.

Eric

 

[scotmartin]

That sounds like it is working beautifully. Just ignore the numbers, and set it by how you feel.



Scot

 

[klenger]

You can change out the t-stat with a digital one.



Here are the instructions.



The operation of yours sound about like how ours was working this weekend. Temps up to 105. The unit ran continuously from about 10:00 am till about 6:00 pm. Temps in the camper were about 83 during the hotest part of the day. Seemed comfortable though with the air moving. Our is a 13. 5K A/C.

 

[slo-ryde]

The recycling you mentioned sounds like the a/c unit has finally managed to cool down the interior of the trailer to the setting on the thermostat and is cycling on/off to maintain that temperature. Other than taking 8 hours to cool down the trailer it sounds like the a/c unit is working as designed. If the discharge temp gets down to 50 degrees I'd say it's probably doing a pretty good job.

 

[TowPro]

I had the same problem with my 2000 ducted AC. When it was real hot, in the direct sunlight the temps inside would hit the mid 80's. My RV guy said he only sees 1 AC unit that needed recharged about every 2 years or so, he said the heat load on the camper, plus the loss in the AC ducts was the problem, and pointed me to a New Style Cover This seems to have fixed the problem. Just turn the cover so it blows AC out the new holes if the AC is not keeping up, and switch it back to ducts in the evenings when the sun load is gone.



I tried it in FLA back in June and it worked great!

 

[BTiner]

Originally posted by klenger

You can change out the t-stat with a digital one.

I went to Was Mart and they did have a Hunter 42995B, and Lowe's had a 42999B. i called Hunter to find out what the difference was. Hunter said that the 42999B was an upgrade so I purchased it. The unit only has 5 connection points while my Duo-Therm has 6, plus it has 2 red wires. I'm nor an EE so I will kep what I have for now. Thanks for your help.





bill Tiner

Here are the instructions.



The operation of yours sound about like how ours was working this weekend. Temps up to 105. The unit ran continuously from about 10:00 am till about 6:00 pm. Temps in the camper were about 83 during the hotest part of the day. Seemed comfortable though with the air moving. Our is a 13. 5K A/C.

 

[EricBu12]

I have this same cover on my Desert fox and it does well... .

 

[Slough]

Glad to hear its working, just a few things.

1. your unit uses R22 not R12

2. you need to remove your filter with the unit running and feel

for cold air coming in from the discharge side NO COLD AIR

SHOULD ENTER THE INTAKE AREA. This will cause freeze up.

{This area is looking toward the back of the intake area. }

3. The grill mention above is for a colman a/c.

Dometic Part number are:

Quick Cool P# 3105935. 005 for Shell White

P# 3105935. 013 for Polar White.