AC compressor will not start

[Jim Flower]

The AC works fine until it is really humid, like in Florida now. It will run for about 6 hours and then the compressor will not come on but the fan remains blowing. The CCC 2 thermostat defaults to an inside temp of 32 degrees F. After shutting down both shore power and 12 V yesterday and then reconnecting , the system started to function again, but only for 6 hours. I seem to be having some sort of icing issue but don't know how to avoid it. Any ideas for a fix? Jim


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[Rich W]

Airflow restriction or insufficient Freon are the two primary culprits

[AnnArborBob]

The fact that your thermostat reads 32 degrees contemporaneously with the shut down of the compressor makes me wonder if it may be the stat that is malfunctioning and telling the AC that the desired inside temperature has been reached?

[richinny]

there are two connectors you an get to after removing the inside cowl. they look like phone cord connectors. if they get wet you'll need to find the one that powers the CCC, unplug the wires and dry it out. when dry the temps will show the correct temp. Lewster advises to use the blower on the hi setting to avoid the freeze ups.

[xrvr]

Don't run it on low fan, try high. Low fan can cause freeze up.

[Jim Flower]

Thank you for all the hints. This has been a recurring issue for the past two years and I have had previous success with drying out the telephone connector. Running the fan on high only has had no effect. I have also installed a new CCC 2 thermostat in the past with no effect on the indoor temp reading. I am beginning to suspect a faulty capacitor in the compressor start up circuit or perhaps something related to refrigerant supply, both of which are beyond my capacity to resolve since my capacity is limited to tapping electrical components on the side and hoping for the best. Time for a trip to Can Am which I always enjoy. Jim


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[Jim Flower]

The usual fix, that is waiting for it to fix itself, has worked and it is now humming along providing copious amounts of cold air. We will see what happens later in the day. For the moment, I am a happy camper. Jim


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[richinny]

jim, check to see that the drain tube is dripping lots of water and sometime raising the nose of the trailer up a bit to help it drain.

[Jim Flower]

Originally Posted by richinny

jim, check to see that the drain tube is dripping lots of water and sometime raising the nose of the trailer up a bit to help it drain.

Thank you for your hints Ricky. I have been monitoring the drip tube today and just made a slight adjustment, raising the bow a bit. I did refasten the tube under the interior cowl yesterday since it had a bit of a droop in it. I do have the CCC 2 set on fan auto and it has relaxed to medium and I am wondering if it should be on manual Hi as previously suggested? Jim


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[richinny]

jim, i use mine on auto 99% of the time and it has been fine. while i haven't checked the fins for icing, i've never noticed a warm output. i have to admit that winters in Miami are dry compared to areas on the gulf coast. my only issues have been the wet connector when it gets 'tropical' here like after the 12" of rain the first week of December. :-) i also found my drain tube clogged a few weeks before inOkeechobee. i use a 25'steel cable to clear the tube and i tape the end to keep it from snagging.

all that being said, Lewster has seen a million more air units than i have ;-)

[Jim Flower]

Ok Ricky, thank you again. I did put some air through the drain tube yesterday but could not really determine if it was clogged or not. To me, initially coming from the Canadian prairies, Fort Lauderdale feels like an out of control giant sauna so your comment about Miami being relatively "dry" is a bit, mmmmm, sobering. Jim


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[ijustlee]

The engineers that designed your AC probably were counting on the compressor cycling off every now and then to allow the evaporator fins to defrost. If you are operating outside of the operating assumptions they made you can have freeze ups. Do you notice a big lack of airflow when your AC malfunctions? The thermostat sensor should be mounted on the evaporator fins and not turn the compressor back on until the fins are above freezing. Do you ever hear the compressor cycle off and on or does it run continuously until you notice a problem? You could try manually adjusting the thermostat to shut the compressor off for 15 minutes while keeping the air flowing on high every hour or so. Leland

[Jim Flower]

Originally Posted by ijustlee

The engineers that designed your AC probably were counting on the compressor cycling off every now and then to allow the evaporator fins to defrost. If you are operating outside of the operating assumptions they made you can have freeze ups. Do you notice a big lack of airflow when your AC malfunctions? The thermostat sensor should be mounted on the evaporator fins and not turn the compressor back on until the fins are above freezing. Do you ever hear the compressor cycle off and on or does it run continuously until you notice a problem? You could try manually adjusting the thermostat to shut the compressor off for 15 minutes while keeping the air flowing on high every hour or so. Leland

Hi Lee,
I think I had managed to do everything incorrectly in order to ensure failure. The engineers designed the unit to work under extreme conditions and be operated in accordance with the instructions outlined in the owners manual. I have followed a number of hints provided here, including yours, and the hints along with following the owners manual have resulted in my AC still running. I think I may be ok for now. Thank you. Jim

[lewster]

Jim,

Depending on the actual operational ambient conditions of your unit, there may be nothing wrong at all. If it starts regularly when first set and energized and runs for a certain time period, even on high fan, extreme heat and humidity will cause evaporator freezing. Other quick possibilities discussed above are blocked exhaust air and/or decreased levels of refrigerant. The latter can be measured electrically by any savvy tech who knows the 'secret formula for calculating compressor amp draw at differing ambient temperatures' and the former is easily done by visual inspection. Another possibility is that the seal between the intake (return air) and exhaust (cold air delivery) has been compromised and the 2 are mixing before entering the evaporator. This is also a known cause of icing.

Once that happens, your unit has a little sensor imbedded into the evap. fins called a 'freeze sensor' (devilishly creative, those Dometic guys….no? ) that connect to your rely control board. The freeze sensor will cut the compressor if freezing is detected in the evap. coil area and will keep the fan blowing as a means of speedy defrosting.

If you have a heat pump, you can also try setting your t/stat to heat (NOT furnace) and see if the icing clears quicker, as what was the evap. now becomes the warm condenser in a heat pump situation.

The other possibilities are that you have a defective freeze sensor or problem in the board. Next time the compressor quits, remove the ceiling assembly and examine the condition of the evap. fins. If they show icing, your have your answer. If not, you may be in for a trip to a 'knowledgeable' dealer (I know they are rare, but they DO exist!) to have the other possibilities looked at.

Good luck!

[xrvr]

I think he may have solved the problem. Hope so.

[richinny]

jim, the good news is that it gets much less humid until March and you'll be the envy of folks back home :-)

be careful blowing air because you can blow the hose off the drain connection at the ac unit. with this humidity, you'll get a steady drip.

[Jim Flower]

Thanks a lot for all the comments. The AC performed flawlessly for the last 18 hours so I (and more importantly, my wife) are very happy campers. Lewster, thanks for the info on the freeze sensor, a little item that protects me from myself. I appreciate the other comments as well. Ricky, the air was provided by a small air pump so hopefully no damage. The drain seems to be functioning well. Now that all seems to be ok, unfortunately I have to head north. Stay tuned for furnace issues. Jim


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[Jim Flower]

Originally Posted by avionstream

I think he may have solved the problem. Hope so.

Me too. One of our favourite rest stops after leaving St George Island on Tuesday is Fanning Springs near your neck of the woods.

[xrvr]

Nice rest area on the Suwannee river.

[B00merang]

Avionstream is largely correct. When I had a similar problem, the AS mechanic told me to keep the setting on "Auto" to keep from freezing up. Also, most air conditioners are sealed up so no freon can be added. What a self-serving design. jon