[Nebster]

I replaced unit 1 (Mach 8) on my coach last fall. It has already started to fail now that I am using it again this spring. It blows cool for a while and then kind of stops blowing.

I'm guessing it is freezing over, and maybe that is because there is not enough airflow. But, I have no idea.

It's technically under warranty, but arranging a tech in the middle of nowhere in rural Canada is not going to be easy. I guess I will deal with it when I get back from Alaska.

[Fulltiming]

Freezing over can be caused by a dirty filter, low refrigerant, or a blower motor that is konking out.

[Richard]

Hmmmmm, a Mach 8 should have a freeze sensor that tells the tstat to turn the compressor off if the evaporator coil freezes.

You might want to poke around in unit and see if the freeze sensor is mounted correctly, and you might want to pull the tstat and see if the freeze sensor wires have been connected or shorted to one another to bypass the freeze sensor.

[Guy]

Perhaps the drain going to you ac was plugged on the old unit, and was not cleared before being  hooked to your new unit. Water droplets then can not evaporate. Richard has taught me to look for the simple first. Just a thought.....

[pairodice]

We had a similar problem if we turned the thermostat down too low (my wife likes to set it to 50 degrees because she thinks it will cool faster :-( )... they will only cool to something like 20 degrees below the ambient temp as I recall ... using the fan on high seemed to help also ...

[Nebster]

Thanks for many good suggestions. I am a total doofus when I am looking at the AC, I have no idea what most of the parts are or what to pull out. (The only thing I know how to “fix” are the start and run caps, which in this case look okay to me.)

I know my filter is clean, and I’m getting good cooling for the first few hours of runtime whenever the unit has not been on recently. (I don’t know if that eliminates the low refrigerant possibility?)

I do think there might be something with the drain. The configuration on each of my roof airs differs slightly, and I noticed water pooled inside the unit, at the bottom where it is mounted to the roof, when I opened it up. I also see a small pump and a clear hose with some air/water moving through it when I opened it. I’m not sure what it’s “supposed” to look like, so it was not something I spent much time studying before, but now you’ve got me wondering if that was installed wrong. Maybe I can find a video or diagram of what it should look like and explore that avenue.

I definitely can’t rule out the blower motor. I probed it in circuit and saw a fairly low current draw compared to what the sticker says, at least at the end when not much was blowing.