A/C blowing hot

[Ladylyonne]

We returned from a recent trip and now our living room air conditioner is blowing hot. I called a local rv service center and the said the ac units are sealed and there's no way to check the freon levels. Any advice? I would like to be able to repair the unit if possible but they made it sound like it's not.

I have a 2013 Big Horn Silverado 35res and I live in Arizona where it's 108ish right now.

 

[cashmore]

Correct, they are not made to recharge / check the freon levels. Without knowing what AC units you have, I would suggest that make sure that the t-stat is set correctly. I assume based on it blowing hot air that the fan is running which should be on the 120v side, but check to make sure you're getting 120v to the upper unit. There may be a problem with the control board that turns the compressor on. Also, and first, I would check the start run cap up in the upper unit. if that capacitor is bad the compressor will not start which will have the unit blow hot air. Here's a link on how to check the start cap https://itstillruns.com/test-rv-air-conditioner-capacitor-7823972.html

 

[danemayer]

Loss of refrigerant is one possible cause, but no need to jump to that conclusion.

Are the return air filters inside the RV clean?

On the roof, the coils need periodic cleaning, especially if you've been around cottonwoods.

 

[Flick]

We returned from a recent trip and now our living room air conditioner is blowing hot. I called a local rv service center and the said the ac units are sealed and there's no way to check the freon levels. Any advice? I would like to be able to repair the unit if possible but they made it sound like it's not.

I have a 2013 Big Horn Silverado 35res and I live in Arizona where it's 108ish right now.

You actually can install service ports on some rv roof top ac units. We used to do this routinely at my company on freezer units that were considered sealed units.
The downside is that the expense probably makes it not a good idea. With trip charges and hourly labor rates, you can tie up hundreds of dollars in an ac unit that doesn't cost but a few hundred more new. Furthermore, if the freon leak is in the coils, it’s generally still unrepairable.
If the other recommended fixes don’t pan out, you could seek a second opinion to put your mind at rest about the replacement.
I replaced our middle ac unit a while back and it took me only a couple hours. For me, it was more economical to replace and move on. I understand doing it yourself is not always feasible.

 

[wdk450]

If you listen intently, and/or feel on counter tops, you should be able to detect if the compressor is coming on. If in doubt have someone start the AC on "FAN" only then switch to "Cool" with the thermostat set appropriately to get cooling. Again, you should be able to detect if the compressor is running. Also if you have an electrical power monitoring system with a display, the AC with compressor running should pull about 12 amps (or more). Cooled air from the vents should be 20 degrees or more cooler than air measured at the intake.

The compressor does have an overtemperature switch mounted to its top that opens when it gets too hot from ambient conditions or cooling system problems. I was able to extend the life of my unit a few months by hanging a room fan on the shroud aiming in at the compressor. I eventually had to replace the top unit.

Top units are available on E-Bay, but you have to get this heavy piece of equipment on to the roof. Otherwise replacement isn't a giant job. Power OFF, Remove trim inside, remove 4 bolts inside going up, on the roof remove the shroud, unplug the 1 electrical connector from the bottom, lift off old unit, remove old bottom gasket on roof, prep roof for new gasket (normally included with new top unit) put roof unit in place, plug in electric plug, work with someone inside to get 4 bolts started (you will probably have to move top unit slightly to get it aligned right). Tighten bolts hand tight (too tight or too loose cause condensate water leaks inside through the gasket), test unit, and replace inside trim and shroud. Then get the heavy old unit off the roof and to the dump. You might want to retest the tightness on those bolts after a few months.

 

[2019_V22]

Just an FYI, any sealed system can be tapped to access Freon levels, and service. Without designed super-heat and sub-cool figures, and/or adequate knowledge of operating pressures, it would be difficult to know the current Freon charge. It can be observed with the exterior rain hood off, and the evaporator shroud cover off exposing the evaporator with minimal to no airflow and see how saturated the coil gets. Today's small units are nearly all 410A, a somewhat dangerous Freon due to it's high pressures as compared to it's predecessor R134A. This is one of the reasons access to the system is not provided as the consumer may be tempted to connect gauges, another is to prevent a point of leakage by sealing off the process stub that was used to factory charge the unit. As mentioned above, your compressor has a thermal overload inside the compressor shell, turning the compressor off in the event of an overheated situation, the 410A systems have a high pressure cut off in the event of an over charge, or dirty condenser coil which can cause the head pressures to rise. What I have found is the manufactures like Dometic are not making replacement refrigerant parts avail for replacement like both coils. If the compressor is not running, aside from a low charge, bad compressor, compressor relay failure, the compressor capacitor, and or exterior mounted overload could be the issue.