Over the last couple days we've been running the A/C at night and sometime during the night the fan basically stops blowing. Not completely, but to the point where it's not effective anymore. Originally I thought it was the filters, but I cleaned them and it didn't change a thing. Then I noticed that a few hours later I'd try again and it would work fine.
I inspected it from above with the cover off while in operation and everything seems fine mechanically. So my theory is that it's the run capacitor failing/overheating. Anyone have another theory that I should explore before ordering the capacitor? Anyone else experience similar symptoms and found a different solution?
[font size="3"]Classic symptoms of frozen evaporator coils. If not enough air is flowing over the cold coils they will freeze. Ice buildup on the evaporator coil will block the fan air flow. Turn it off and the ice eventually melts. Then, later, everything works as if by magic. This frequently happens at night when the fan speeds are low and temperatures are lower. The only cure is setting the fan higher or the temperature higher.
[a href="http://stilesheatingcooling.com/what-causes-an-air-conditioner-to-freeze-up/"]http://stilesheatingcooling.com/what-causes-an-air-conditioner-to-freeze-up/[/a]
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What Charlie said.
You also might be unintentionally recirculating the air from the discharge back to the intake- short circuiting its called. This will also freeze the coil.
Pull off the inside cover of the A/C and look up inside. There is a short duct which goes from the discharge of the roof mounted unit to the discharge register in the cover. If this is missing and or is loose it will cause short circuiting.
David
We experienced the same symptoms with our Dometic Penguin rooftop on our toyhauler, I brought it to a dealer and they said the return air was mixing with the discharge air.
They re-worked the duct between the rooftop unit and the ceiling assy.
I had to absorb the cost because they said it was not installed at the factory correctly.
The next trip was 500 miles away and during a rainstorm on our first night of the trip water was pouring in from the roof, we packed up and returned home.
I pulled the ceiling assy and found the bolts were not tightened at all, I would assume the tech working on the AC got a text or Facebook message when he was at the point where you tighten the bolts.
Ruined trip.
Thanks for the tips guys. I've had both covers off and everything seems to be in fine working order. As a computer guy we call this a PICNIC (problem in chair, not in computer). Sounds like I need to ease up on the thermostat so it can turn off every once in a while to defrost, and keep the fan speed high. I'll try it tonight and will report back the results.
I did a couple things differently last night that seemed to work:
1- Gradually turn the temperature down so it doesn't have to go from 80+ to 68 in one run of the compressor. I listened carefully to make sure the compressor was cycling before making adjustments.
2- turn the fan on full
I guess it's just something I'll need to stay aware of from now on.