Problem Coleman ac stops blowing cold 115° days

[16 yellowstone wide open]

Alright y’all, I got a question. I have a Coleman (unsure what model) it’s a dump unit, (no thermostat) that will blow ice cold all day and all night..
until we got into this 115° weather here in Texas.
It will blow ice cold until the heat of the day then it starts blowing hot.

Turn it off for 30mins to an hour and it will blow ice cold again

Compressor is on, fans on,

I’ve had 3 different techs come out and say there’s nothing wrong with it. I don’t understand why it keeps “overheating”

I’ve done a lot of research and no one has said anything about a AC unit “overheating”

Camper is not in the shade

Thanks in advance.

 

[Kevin D Pem]

Nothing wrong with your ac unit!!!

According to a friend the head pressures at those temperatures is high enough for the temperature protection in the compressor to shut down the compressor.

What could have been done to reduce the load on the compressor, was not considered, therefore what is, is.

The good news is there is a cure!!!

Expensive rigs are built to overcome this short coming, add more ac units! But wait!!! You can become a Bubba, and install misters to cool the air around the ac, just remember to install a sacricial filter designed to stop deposits from forming on the condenser coil or plan on replacing the unit in short time!!!

Hope that helps!!!

 

[16 yellowstone wide open]

I did add more ac units. This is a added one. But I don’t get it. You say it shuts off the compressor? The compressor is still running.

 

[B52Bombardier1]

Is your evaporator "iced up"?


Rick

 

[Kevin D Pem]

The key indicator the compressor is not running is its blowing hot air. You state that it blow stupid cold air in the morning, and again after it is restarted.

Unless you are saying there is ambient air coming from the vents,with no change in temperature? As hot air, or an increase of temperature, as in heating element?, or heatpump. The compressor is shutting down.

Without provocation the compressor is overwhelmed by the 115 degree temperature. We too are feeling the temperature! 5:00pm and 115 degrees, it is cooling down! Yah!

 

[Rich W.]

Try measuring the vent temp. If its 115° outside and you’re getting 90-95° air inside the unit is working as designed. Its just cooling very hot air.

 

[16 yellowstone wide open]

Try measuring the vent temp. If its 115° outside and you’re getting 90-95° air inside the unit is working as designed. Its just cooling very hot air.

Blowing 50-60° when it’s was 110° yesterday
Then all the sudden it’s blowing 100° air.

 

[16 yellowstone wide open]

Is your evaporator "iced up"?


Rick

No sir,

 

[B52Bombardier1]

I'd love to see the low side and high side refrigerant pressures when these big temperature swings occur. Its either a refrigerant line blockage somewhere or more likely, air to the condenser is stopping or is blocked somewhere.

Also, a few squirts of cold water sprayed onto the fins of the condenser when its blowing hot would be diagnostically very revealing for me. Head pressures should drop and cool air should flow again.

Rick

 

[16 yellowstone wide open]

I'd love to see the low side and high side refrigerant pressures when these big temperature swings occur. Its either a refrigerant line blockage somewhere or more likely, air to the condenser is stopping or is blocked somewhere.

Also, a few squirts of cold water sprayed onto the fins of the condenser when its blowing hot would be diagnostically very revealing for me. Head pressures should drop and cool air should flow again.

Rick

I will try that thank you.

As for pressures. They said it was good when they tested it. Or they where just tired of being on a roof in 150° temps

 

[TheLooks]

They were not testing pressures, you cannot without penetrating the lines. No one(almost) tries to refill the charge in RV ac units. Yes there are some that claim to be able to. Most RV techs are not HVAC guys.

 

[Kevin D Pem]

They were not testing pressures, you cannot without penetrating the lines. No one(almost) tries to refill the charge in RV ac units. Yes there are some that claim to be able to. Most RV techs are not HVAC guys.

They do, they can, I have, but that was when r12 was readily available.

 

[Joe Hogan]

BTW have you checked the voltage of the line powering your RV, if you are on shore power, or out of your inverter if on Battery power. Low voltage can cause interesting problems.

 

[Wemustrv]

AS others have mentioned it sounds like frozen. While you have had techs look at it I would also check or recheck and clean the fins on the exchanger/ evaporator. In these temps it does not take much restriction to affect the performance.

 

[LMHS]

I live in a NM desert. I live with triple digit heat every summer (over 105F most days and as high as 135F).

There is probably nothing wrong with your unit. The techs are probably tired of telling people that air conditioners don't like triple digit heat (no one ever believes them). Also they only cool 20 to 35 degrees cooler than ambient temps. Most of the RVs in my park have sprouted "window shakers" when their rooftop airs pooped out (some have burnt up the compressors). Not all RV parks will allow window shakers. Did I mention the rolling brown outs kill compressors? Our local power company says we don't have rolling brown outs. I guess it's just our imagination.

Compressors don't like to run when ambient temps are high. Whether it's in a refrigerator, freezer or air conditioner, they all have a limit and they will stop. Sometimes permanently. The only way you will keep a compressor going in these high temps is to be pulling the air for cooling the compressor from under your rig where it tends to stay shady. This is where some of the DIY builders were pulling their exterior air for the mini-splits they installed in the basements of their coaches. But even that has it's limits.

I have two 6000BTU "window shakers" that were built into the fore and aft bulkheads of my bus (you can't see them). The bulkheads double as plenums to bring air to the compressor. But when the exterior temps are above a certain point, the compressors will shut down to 'save" themselves from burn out. The fans keep going but the compressors stop. I just plan for it.

1) I have a reflective roof coating on the roof. I renew it every so often in the fall (recoat at the end of the "warranty" listed on the can).

2) I have a sandwich of Reflectix/cheap packing quilt blanket/painters tarp hanging on all my windows as curtains. It goes a long way to cutting down the heat intrusion (and works in the winter too when temps drop to single digits, sometimes with a "-" in front of the number). I buy the packing quilts from Harbor Freight as you can't wash them very well and I just toss them every so often. I have one hanging over the entry door too. The screens in my windows are "solar" screens which block a great deal of heat gain.

3) I do my "hot" things in the early morning. That is anything that generates additional heat, like running the dishwasher or doing laundry, before the temps rise too high. I eat my main meat at lunch because shortly after that it starts getting too hot to eat. Supper is a cold thing like a bowl of cereal with a protein shake in it rather than milk (which makes me sick because it's too hot) or a cold sandwich. Hot meals make you feel warmer.

4) I take lukewarm showers (never cold) when I get too hot. I wear lightweight "stay dry" or "moisture wicking" workout clothes. I drink iced tea all day and take my vitamins at night to replenish what I sweat out during the day. I also take magnesium glycinate at night to combat muscle cramps from loosing too much electrolytes during the day. (Different types of magnesium does different things)

5) I have the bus divided into sections. The bus has a center aisle layout. Front to back, the bus layout is salon (and entrance), galley, bathroom (split - toilet on one side and shower on the other), laundry and closet, then the bedroom. The airs are in the salon and the bedroom. I have a dog so she needs to be able to roam front to back. I use curtains (folded over flat sheet, blanket, beach towels or painter's tarps) to block off the bedroom from the rest of the bus and the salon from the rest of the bus. This means each air conditioner is cooling a very small area. I open windows (still covered) in the "hot" part.

6) I mounted several 9" floor type fans in several places, on the ceiling so they can pivot. The one in front of my residential refrigerator and upright freezer blows to the ceiling, forcing air behind the freezer and refrigerator to help keep them cooler. This helps to move the air so there are no "puddles" of hot or cold air. It helps to move the hot air out the windows in the hot parts of the bus as well. I use the exhaust fan over the range to move hot air out of the galley. The hot part of the bus gets almost as hot as exterior temps. I replace the fans every other year or so because they run almost constantly, year round.

Sites like builditsolar.com has projects and info on energy that you can use in an RV if you can figure out how to adapt some things. I got the idea for my interior storm windows from that site (my storm windows also open so they stay up year round).

I could tell you more things that I do but this is too long already. Someone, or several someones, will be complaining about the length. And I have to walk the dog before it gets too hot.

 

[Rich W.]

They were not testing pressures, you cannot without penetrating the lines. No one(almost) tries to refill the charge in RV ac units. Yes there are some that claim to be able to. Most RV techs are not HVAC guys.

The guys at National RV Refrigeration in Shipshewana said they had a guy who would do it, although with no warranty. That was the first I have ever heard of someone willing, and a few years back I called many HVAC companies in multiple cities from Salt Lake City to Memphis while en route to Florida and found no one. Finally bought a new unit and installed it while camping. So yes, very rare indeed.