Air Conditioning - What should I expect?

wdk450

Well-known member
Gang:
I was in warm weather last week with our 3670 RL, and don't know if there are problems with the AC or it is doing all it can do. We heard a forecast for 95 degrees that day, and had to be out all day, so we turned the AC on high, thermostat set to 68 degrees, when we left in the morning. We came back to 95 outside temperature and 90 inside temperature. I had put in the diverter modification before, seeing if that would help.
When Heartland says they put the coaches in an enviromental chamber at 100 degrees, do they have the coaches fitted with the opeional 2nd air conditioner to make the claim of cool temperatures inside?
 

Peteandsharon

Well-known member
Bill and Deb,

I'd would say that the first thing that you should expect is to be grateful that you didn't leave a pet in your rig all that time. That could have been a tragedy. I am currently debating the second air conditioner question myself but my thought is that you definitely have a problem. Your rig would certainly not have been able to stay at 68 degrees but 90 is ridiculous. We have not yet had the 90+ degree test in our Bighorn but our experience with other trailers is that it will be a bit warm but I think 90 degrees is ridiculous.
Pete
 

slmayor

Founding California Northern Chapter Leader
Bill, on our first hot trip, we found our air conditioner would "freeze" up if we ran it on low for extended periods. The fan still runs, but the air coming out isn't cold. After shutting it off for awhile it would come back on and work properly. When it's hot, we now run it on hign and it seems to not have the problem. We haven't left it all day however, so not sure if that would be an issue or not. We generally don't go where it's hot, so no second AC on ours either.
 

SmokeyBare

Well-known member
Ray,

Inside the Grill cover of the A/C... there is a thin metal wall between where the Exhaust side and the Intake Side of the A/C unit. This wall is the only divider that keeps the cold air from mixing with the warm air being pulled back into the Condenser unit.

This metal wall can have leaks that allow the cold and warm air recirculate inside the A/C unit. That Can cause the Condenser to frost up... even freeze so bad that the air flow will be restricted. One other spot to have checked out as well is a small thermo sensor that should be attached to the Condenser fins. This sensor detects when the freeze up is happening and shuts down the A/C to protect it from a burned out fan motor or worse.

IF you feel comfortable enough to remove the plastic ceiling grill... using a flash light to look inside for the sheet metal divider wall... Looking if it has fallen down a little... or if you can detect any gaps where the air cold air can mix with the warm return air... I used the metal duct tape to seal this very well... and I had to locate the sensor that was NOT attached to the Condensor... and place it in it's proper location.

Of course a dealer can do this work as well...

Good Luck...
 

Rickhansen

Well-known member
WDK,
Our '09 3670 has two A/C's. We've been a little over a year in (full-time) North Central Florida, so I can offer our experience. Solar heat load is the killer. I've done the "TimK" mods (which help), as well as went to digital thermostats (We have the 15k BTU in the living room and a 12k BTU in the bedroom).

First, resist the temptation to run on low fan speed every chance you can. As these units have one fan motor for both condensor and evaporator, efficiency goes way down in low speed and can cause freeze up and is much harder mechanically on the compressor.

I stagger the setpoints between the two units. higher in the bedroom during the day, lower at night. That tends to match the "lead" unit to the load and our tastes. It helps with the high humidity here. Fan noise is our only objection, but you can't have everything.

At outside temps frequently at 100 degrees and high humidity, we can maintain 78 derees running in that manner. Above that, the inside temp creeps up proportionately.
That is acceptable in this climate for us.

Your performance will obviously be less with one A/C, but I would guess that at 95 degrees outside, full sun load, your living space should hold around 80 with the A/C running continously. The bedroom will be warmer, as the heat rises into that area and has a harder time returning to the return vent.

I've added filtration (Filtrete media) on the A/C return vents to protect the coils, minimize dust and allergens. It also helps with some of the fan noise. We change these often during the summer months.

Hope this helps.
 

jmgratz

Original Owners Club Member
I have always been told an ac unit should be able to provide a 20 degree difference from the outside temp. That is if 90 outside 70 inside; 95 outside 75 inside etc. If you can't get this minimum then you may have an ac problem. Also check the temperature of the air coming out of the vent. That can tell you if you are getting cool air out. My opinion is you should have 2 air conditioners on your RV because no matter where you travel (even Alaska) you are subject to 90 degree days. It is kind of like saying I don't need a heater because I don't travel where it is cold. How can you control the weather? I have been very hot in the north in the summer and very cold in the south in the winter. Just depends on Mother Nature.
 

wdk450

Well-known member
AC Temperature Differential

JM
I worked in Auto Parts as a teenager and attended an Air Conditioning maintenece service school given for our mechanic customers by an AC parts vendor. This 30 degree temperature differential you talk about is not necessarily between the outside air and the output cool air - rather it is a measure of the differential between the return air to the AC and the output cool air. The return air MAY be outside air, but is usually just room air being recirculated.
 

jpmorgan37

Well-known member
With two A/c's and dual pane windows and you should be able to maintain a comfortable temperature in your RV. With the temperature at108 degrees, we were able to keep the inside temp in the mid 70's with out the A/C's running constantly in our Landmark. With one A/C and single pane windows, there isn't much hope of keeping it cool. That's what we experienced in our last SOB.

John
 

Peteandsharon

Well-known member
Well Bill and Deb,

You scared me enough to get off my duff. Since we do have a furry friend who travels with us, the thought of leaving him in the Bighorn in 95 degrees without a second A/C caught my attention. So I went to my dealer this morning and arranged for them to install a Coleman Polar Cub 9200 BTU A/C. I think the 9200 BTU is the perfect size for the bedroom so that it will not cycle off too soon to properly dehumidify. I guess sometimes you need a wakeup call and you gave me mine.

Since I had the fantastic fan in the bedroom before I didn't want to simply lose that. So I am going to have them swap that out into the commode room. I asked the dealer if that would work and she said "Sure as long as you only have it set to blow out". The black water tank vent pipe comes up right there and having the fantastic fan set to pull that air into the rig might have been a little interesting.
 

ChopperBill

Well-known member
Good choice on the Polar Cub! From what I witnessed they work pretty good in a small area, like our TC and the bedroom in our Bighorn. A big plus is they are a whole lot quieter than the bigger units.
 

Chickie

Member
Thanks for sharing this...

:eek: ditto on the scare...we plan on keeping our kitty with us when we are out. We have the BH 3400 RL. Haven't used it in the summer heat just yet. Didn't realize the AC wouldn't cool the unit to keep it comfy. The Coleman Polar is mentioned. What size would you recommend for the bedroom. Quiet would be a plus.
 

jpmorgan37

Well-known member
For what it's worth, we have a 13.5k in the bedroom. In moderate temps (mid 80's) it will keep the whole house cool. We don't run it at night because of the noise level and run the main unit. In high temps we run both units in the day time and they do a good job. Also, both of our units are heat pumps and supply much of our heating requirements in the winter.

John
 

wdk450

Well-known member
What is this part?

Gang:
While working on the AC wiring on the inside in the AC unit (another story), I had a round sensor (?) with wires on it fall down from wherever it was attached. It is about 1 inch in diameter, about 1/2 inch thick with 2 wires connected to it.
Does anyone know where this is supposed to go, and what it is?
 

jnbhobe

Well-known member
Its probably the freeze sensor, It goes on the third coil up on the condenser. The little formed wire fits around the coil. JON;););)
 

62cwil

Active Member
Air Conditioners - What can I expect

Until a month ago I owned a 35 foot 5er McKenzie Lakota with one 13500 BTU A/C. Over the last few years I have spent up to two days in 100 degree weather and never seemed to be a problem. I now have the Eagle Ridge 29 foot with a 15000 BTU A/C and am going to Phoenix for 4 nights where temps are 112. We will be in the unit most of the day and out from around 4 to 10 each night. What can I expect and has anyone experienced these temps with one air conditioner and how was it.
 

2010augusta

Well-known member
We are in Southern Texas right now and the afternoon temps are around 104. We have the main unit set to about 83 and the bedroom set to 72. (we are currently sleeping during the day time and working the night shift. The main A/C runs constantly on high speed fan but can cool the back half to the low 80's, maybe cooler.
 

62cwil

Active Member
Thanks for quick reply. I suspect you have a very large rig to cool vs my 29 which is actually 32 feet with two slides and only one ac. In looking at the carrier web site it says rated up to 140 degrees.
 

wdk450

Well-known member
My Solutions/Results

Gang:
I started this thread, have been reading the recent postings, and thought I would share my fixes/high temperature experiences since I now consider this issue "fixed". I have a single 15K BTU unit.

First of all, I obtained new, adjustable air conditioning duct outlets, and installed them while taping up all of the connection holes so there was no leakage into the space between the ductwork and the room ceiling. The outlets I obtained at the local trailer supply did not have as large a hole as Heartland had cut out, I had problems making all of the mounting screws bite, but I got them in.
I went all through the kitchen area air conditioner air inlet/outlet fixture with tape sealing up all encountered leaks between the inlet and outlet, and better sealing up the duct inlet connections to the air conditoner. I make the Timk mod metal piece and installed it. I finally took the rig to a local 3rd party professional (RV Dr. George) who's tech checked everything out, remounted the Timk piece for best efficiency, and remounted the freeze sensor where it belonged. He could only test the system in 85 degree temps that day, but I could tell that the airflow was vastly improved in the bedroom, and with the adjustable air outlets, I can now "tune" the system as needed.
A couple of weeks ago I attended a 75 birthday celebration for my sister in Porterville, Ca (near Bakersfield). The outside temp as we unhitched was 106 degrees, and inside the rig it was 104 degrees. I got the AC going and got the temp down to below 100 degrees in about a 1/2 hour. We then bailed for my sister's air conditioned house, while the rig cooled. We came back in 3 hours, and the temp was down to 80. It kept cooling during the night and got the inside to the low 70's overnight. I noticed overnight I would occasionally hear the compressor cut off while the fan remained running. I am guessing that was the freeze sensor at work. I colud observe a steady drip of condesnation from the AC coming off the roof in the morning. The humidty was not very high there - 30 to 40 percent. We prefer the nighttime temperatures to be in the 60's for sleeping, but could not get that. The lows during the night were in the low 70's, but the highs were 100-106 during the day. The daytime inside temp would get up to the low 80's, but with the outside heat load and just 1 air conditioner, I deem that acceptable.
We hope to be staying in cooler climates as much as we can in the future.
 
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