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Cruise Air off but freezing up
The problem seems to have started a couple months ago when Ian spent the night in the bus while we were out of town and flipped a breaker by cranking all of the A/C’s down to the low 60s. Got that straightened out eventually, but then I was confused by why one unit wasn’t turning on when checking it remotely. I was able to see that the temperature sensor was reading low 60s so figured I would just calibrate it next time I was there.
The next time was yesterday. I had a really hard time getting the temperature to calibrate. It kept trending up, then trended down. When it eventually stopped for a while I set the cool temp to where it would kick on as it was so darned hot. A few minutes later I noticed icy water flicking me on the neck and when I took off the return air cover I saw the filter covered in ice!
I let the unit sit off a couple hours and restarted. It was good for a while but the temp sensor stopped working again. There was a little water on top of the unit under the sensor wire so I thought it might need to just dry overnight and I turned off the unit at the controller. This morning everything was off again but the filter had ice on it again!
Now I have it turned off at the breaker to let everything melt off and dry up. After that, what do I need to do?
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15 Replies
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Is the evaporator fan blowing as it should be? You could try removing the SMX control, unplug the cable and see if that helps, kind of a reboot for the control. You can also do a factory memory reset by the following:
Press OFF, SET and FAN simultaneously, then press SET, wait a few seconds for the computer to restore memory.
Jeff may jump in, could be a freon problem as well. Remember, AAP is the go to place for help.
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You gotta speak slowly, Tom. I’m a doctor, not an A/C tech!
Whats an an evaporator Fan?
I did do a memory reset yesterday for lack of something better to do and didn’t think to mention it because I thought it was not important.
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I don’t think the problem relates to tripping the shore power breaker.
Having said that however the starting point for diagnosis is as suggested, a call to AAP. They are truly the experts and it is likely they can walk you through some diagnostic procedures. Typically however the SMX controls usually provide a code so I suspect that will be the first thing they attempt to find.
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Bonz – Evaporator fan is the thingy that blew ice onto the top of your head, how’s that.:)
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Karl,
The evaporator fan is the fan that blows cool air into your coach. Your compressor compresses the refrigerant making it hot and dense. The refrigerant is cooled by running it through a radiator, then it is routed through a high restriction nozzle, the expansion cools the refrigerant which then is run through another radiator, behind which is the evaporator fan, which blows the cool air for all of our pleasure. Kind of like when you freeze a mole off a patient with nitrogen. -
Karl,
Here is the simplest way for you to understand refrigeration……………
Wet your arm and then blow across the wet spot. It will feel cool.
The reason it feels cool is because when you blow across the wet spot some of that moisture evaporates. (notice the term)
In order to evaporate, the moisture is absorbing heat, and so the area surrounding where evaporation takes place feels cooler because it is giving up heat for evaporation.
In the AC system the evaporation of the refrigerant takes place inside a closed system, but the heat comes from the air blowing across the evaporator coils. The fan is like your breath blowing on your arm.
All the condenser unit is doing is taking that evaporated refrigerant and compressing it, starting with a hot vapor under pressure and then liquifying it in the condensing coil so it can return to the evaporator as a liquid and start the evaporation process all over again.
To understand the condensing part of the equation, breathe on a mirror. Your breath has moisture in it, but it is a gas vapor. When it hits a cool mirror, it condenses. I know that as a doctor you are familiar with the condensation process because your patient has died when he cannot fog a mirror.
You may think as a doctor you are therefore unfamiliar with air conditioning systems, but as shown above you actually know all about refrigeration and its terms.
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I don’t care how much you guys raise my dues, I wouldn’t miss this GOOD read’n for nuth’n!!!!
Mark
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Mark, with talk like that Tom will put an addition on his new house before it is even done.
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Thanks guys. Much more clear now, lol, especially Tom’s!
Tomorrow I will try to give a call to AAP.
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Karl,
Jon, is off his “meds” again.
AL
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I thought AAP were advertisers but all I see are converters. I also can’t find them online. Anyone have a phone number?
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I ended up talking to John as Fred was out and we diagnosed a bad probe after I switched the control modules and had the same problem. Has anyone ever spliced a new probe onto the whole line, or do you just run a whole new line? It seems the work difference is substantial and expensive.
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The answer to that is the type of probe or sensor.
Some designs are a gas or liquid filled bulb with a very small diameter capillary tube that goes to a pressure sensing switch or device in the controller. That type typicaly requires a new probe and possibly the controller and it has ot be fished in and out of position.
The second type is a sensor or probe like a thermocouple that is just a pair of wires, Typically they will not require a controller replacement, but like the other type have to be fished into place.
It may take some time to install a new sensor or probe but it is usually not going to involve anything more than patience. The worst to do are the probes relating to the center SMX controls.
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