t1550 ac unit is mine working corectley

[mventrice]

hi this is the first camper with a ac. i tryed it for the first time today after cleaning it out the outside and cleaning out the filter. the camper was in direct sunlite and was about 94 degres it took about 1 1/2 hrs to cool it down to aroud 85 degres it was confortable inside no humidity and the unit made plenty of water drip off the roof. how fast do these usualy cool a camper of this size ?

[JohnB]

Hi mventrice

How long depends on how big the camper is, how many windows is in it and how big the AC unit is.

If every thing in the TT is heated up to 94 degrees like what happens on a hot summer day, (couch, wood, carpet etc) and it took 1 1/2 hrs to cool down to 85 the first time, this does not sound that unheard of. Once all the inside stuff is cooled down it will work less hard to keep it that way.

If you feel the humidity drop and it feels cool, then life is good. I can’t remember the exact number they are designed to but I "think" they will only drop the internal temp in the camper some 15 degrees max. I would have to dig up that number to be exact but it is not going to go from 94 to 65 even if it never shuts off. The cool loose, heat gain from sun shining in and lack of AC capacity will never keep up. These AC units are not that big like a home one.

Hope this helps

John

[Lode]

With a camper that small, I'd think the time you spent with the AC on should've dropped your temperature more than just 10 degrees. What year is it? I've got ice on my mustache after a 1/2 hr after cooling it from over 100 degrees on the thermometer reading inside our camper.

What happens when you turn on your AC? Am I right to forcast that it is cold air for a bit followed by warming air? If this is the case the coils are probably freezing up. This happens for a few different reasons...

-the air inside the camper is warmer than the outside air, this usually happens around 60F or lower.(not your case)

-a lack or overfill of refrigerant in the system. When it is short on charge or over charged the coil runs very cold and ice grows. Once the ice starts to gain a foundation it keeps on growing until the coil and the refrigerant lines freeze into a block. This process is sped up by a high humidity.

The bad news is, when you continue to run an AC with a frozen coil you can damage your compressor.

I'd get up and pull the cover, clean up the unit of any debris or build up. Make sure your condenser evaporator is set up to drain properly and isn't clogged or blocked in any way otherwise it can also speed up ice formation. You said yours did drip out of the gutter, but that could've been ice melting off the block that formed.

A temp solution(or permanent for folks who have priced a new roof mounted RV AC unit ) is to monitor the feel the of the air being blown, when it starts to grow warmer turn the unit from 'cool' to 'fan'(or turn it off completely) and let the coils thaw for 15 mins or so. Once the ice thaws(the speed of the drip will slow down from the gutter ) you can rinse/repeat until your trailer is chilled.

I hope that helps a little in your troubleshooting.

Take care,
Jason

[Steve Collins]

Some things you can do that may make a big difference right away. First, as Jason said, pull the cover and clean the roof-top unit. Pay particular attention to the vanes of the heat exchanger. I like to use a shop-vac set on exhaust to blow air through the vanes and remove built-up dust and dirt.

Be very careful with these vanes as they bend easily, and the more bent they are, the less efficient they are. If they are badly bent, you can buy a "comb" specially made to straighten these vanes. It's the same one used to straighten vanes on automotive radiators, so you'll probably have good luck finding one at an auto parts store.

On the inside of the trailer, drop the cover of the AC, pull the filter, and clean it. Easiest way to do that is to take it outside and hit it with a blast of water from the garden hose. Let it dry and then put it back. A blocked filter will dramatically impact the unit's cooling ability.

While you have the filter down, visually inspect the air path above it and make sure that it is not blocked. In a small trailer like the 1550, you should get a really good air flow out of the AC system. So if the air flow at the output vents seems "wimpy" to you, you may need to inspect the ducts for blockage, too.

Some of the AC's for RV's have a heating element in them. If your unit has this, double check to make sure that it is turned off.

One more thing... if you have the standard DuoTherm thermostat, it is possible that it may be defective. Our's was, and while the fan was running on the AC, the temp settings were so messed up that the compressor was only coming on once in a great while. To check that, set the unit to COOL, the fan to AUTO, and bring the temp setting all the way down. If the unit magically begins cooling better, you can then begin to adjust the thermostat and find out how far out of whack it is. Ours was so badly inconsistent so I opted to replace the whole thing. But it was off at least 30 degrees on both heat and cool.

A replacement DuoTherm at the RV store runs at least $55. The Hunter digital thermostat replacement has been discussed several times in other threads on this forum. It is very easy to do, only costs about $22, and the unit is readily available at Wal-Mart and other stores. If the thermostat turns out to be your problem, then I highly recommend this swap.

[mventrice]

when i bought the camper 3 weeks ago i removed the cover cleaned out the unit flushed the evaporator with water it is clean i also cleaned the fan fins. i washed out the internal filter the exterior of the unit looks good there is a lot of rust build up on the motor but nothing else. the camper is a 89 i asume the ac unit is to. the ac is r22 and has no service fittings.

here is a little more info on the unit from yesterday.
internal temp of camper was about 94 degres
return air temp was about 81 (i gess becus the air was moving it was lower then the internal air)
blowing temp was about 63 degres

unit blew cold air entire time that it was running.

yes everything in the camper was baking at 94 degres when i started the unit. the evaporator was also in direct sunlite but there was nothing i could do about it.

[JohnB]

mventrice

My refrig experience stops at commercial cold storage (apples, pears, fresh fruit) and heat pumps.

Steve and Jason are into the camper ones more.

However, if it is 94 degrees on the intake and 63 cooling all in one pass, that is a 31 degree drop in one pass which sounds right good to me but I do not have the spec on the units.

The rest is then up to actual capacity, meaning BTUs, If the initial heat load is high then capacity will dictate how long it will take. It will take time and then if the heat is still coming in, (sun in windows) or the cool escaping, (leaking windows) eventually you will hit equilibrium and can’t get any cooler even if the unit cranking out the right temp drop.

And then like Lode and Steve talked on, if the unit is not efficient due to restricted coils, well it can’t keep up the same temp drop in one pass.

If you are getting a constant 30 degree drop from intake to cooling, that may be all she has. A froze up coil will change that spread.

Again this is based on commercial units cooling square footage 50 to 100 times larger and heat loads of 500 bushels of fruit at one time.

Hope this helps

John

[Lode]

Originally Posted by mventrice

unit blew cold air entire time that it was running.

If your returned air fed to the intake is around 80 degrees and the cooled air output is 60 degrees I believe your AC unit is performing its designed duty.

Kinda stumped other than to ask if you might have overlooked an open roof vent or window while trying to cool the trailer down? (I know a friend of a friend who's college roomate did that once hehe ) Were you in and out of the trailer a lot while trying to cool it? That can also make a drastic difference until, as John pointed out, the surface temperature of the interior components drop, which definitely takes a lot longer than the internal air to cool down.

When I set up camp in the rediculous heat, my wife and mother in law know I want keep it closed up for a 1/2 hr to not interupt the cool down of the inside.

Take care,
Jason

[mventrice]

after reading the last post i relized that i had left the 2 bunk windows half open i have to finish the under the cabinet radio/ tv instalation later today i will close the windows and try it agen.

its funny becus at work we have a storage shed as an office in a wherehouse. with a window unit in the wall and the door is open more then closed and it gets to be frezing in there but the unit is probibly over powerd for the room. and its also in shade all day.

thanks for your help

check out my mod in the mod sections 7" under cabnet radio/tv pics will be up in a few days

[mventrice]

closed the 2 bunk windows inside temp 101
droped temp to 86 in 1hr 15 min

[mventrice]

2hr 45 min
temp is down to 81

[Tweety]

Sounds to me like it's working, but not correctly. When we had the QUE it only took a few minutes to go from 90 to icebox in there.

[mventrice]

went down to 79 in about 3 hrs. any ideas on what is wrong. where can i get service fittings for this ?

[JohnB]

What TT do you have? Looking for Sq feet. Sorry just saw it a T1550. What year? Tell us the inside cubic feet.

How many BTU AC it is it?

TT size makes a difference. Our T2499 came down fairly quick. Our T310SR takes a lot longer. More windows, more sq feet more stuff inside to coo down. But once down the it maintains no problem.

If the gas is low, that will affect how cold 1 pass thru the AC unit is. I thought you had 30 degrees per pass?

If the unit is small in capacity compared to the heat coming in or what is already in, that will add time or may never get there pending how good or bad it is.

I sounds like your unit is working, the issue is what is normal for your size TT?

John

[Lode]

Originally Posted by Steve Collins

One more thing... if you have the standard DuoTherm thermostat, it is possible that it may be defective. Our's was, and while the fan was running on the AC, the temp settings were so messed up that the compressor was only coming on once in a great while. To check that, set the unit to COOL, the fan to AUTO, and bring the temp setting all the way down. If the unit magically begins cooling better, you can then begin to adjust the thermostat and find out how far out of whack it is. Ours was so badly inconsistent so I opted to replace the whole thing. But it was off at least 30 degrees on both heat and cool.

A replacement DuoTherm at the RV store runs at least $55. The Hunter digital thermostat replacement has been discussed several times in other threads on this forum. It is very easy to do, only costs about $22, and the unit is readily available at Wal-Mart and other stores. If the thermostat turns out to be your problem, then I highly recommend this swap.

From what you've described so far, I really think this is what you're looking at.

Can you hear the unit cycling on/off at all? Try moving the thermostat dial back and forth on all 3 setting of low/med/high 'cool' while it's running and listen for the cycling of the compressor.

This is what mine looks like on my 92 Sunline. The 85 Fleetwood I owned had the exact same.


Let us know how you make out.

Take care,
Jason

[mventrice]

i here the compresor come on only when i turn it on i never hear it cycle i was in the camper for about 3 hrs the other day when i was installing my under the counter tv (listed in mods if you want to check it out)
i am a truck mechanic and have only basic knowlage in a/c
as for square feet the inside is aproxitly 15 ft x 7 x 6
hope that helps.