Continued AC Saga

[Kountryguy]

About a week ago I had my 15,000 BTU ducted Duo Therm AC replaced. It had to be a special unit to fit my Newmar trailer. It was installed using the old control panel and existing digital 4 button thermostat. I operated fine for a couple of days, not 24/7, just during the day. Yesterday I turned it on and it ran for about 1 1/2 hours before stopping. I checked breakers, etc. and every thing seemed fine. I shut the thermostat off. waited a couple of minutes, turned it back on and it started up. It ran for about an hour before I shut if off for the night.
Today I started it, ran for about 1 hour and off it went. I turned the thermostat off, waited a couple of minutes, turned the thermostat back on and it started. Now it runs anywhere between 15 and 40 minutes before shutting its self off. An other thing I found was that If I do nothing, and just wait, it will restart itself. I have the thermostat set much cooler than the inside temp and the fan set on medium.
Does anyone have any ideas on what the problem might be and how to troubleshoot it?
Thanks for any suggestions. I am at my wits ends.

[Kountryguy]

Update: As suggested, I ran the fan for about 1 hour with no problem. I then switched to cool and the compressor kicked on and ran flawlessly the whole day. I shut it off for the night. Started it yesterday about 11 o'clock and it ran properly for about 12 hours. I was ready to go to bed and thought I would lower the thermostat a few degrees before shutting it off for the night. the compressor kicked on and then after about one minute, shut off.
I did not try to restart it until today. This morning I turned it on and it started up and has been cycling properly for about 2 hours now. I guess I will just keep my fingers crossed.

[Kountryguy]

To answer some of the questions. The service guy showed up with just the new thermostat and not the new control panel. The new thermostat will not work with the old panel. We did use the old freeze sensor, add I believe it is hooked the same as on the old one. I went up, while it was running, and carefully moved around all of the wire nut connections I could see, and nothing felt hot or seemed loose. Today I will try running just the fan and see what happens. Thanks, I will keep you posted.

[dougrainer]

Chris Bryant wrote:
Double and triple check the freeze sensor and room sensor to make sure they are plugged in to the correct plugs on the board.

On this year model Newmar, the wall tstat will be the room sensor. Also, WHY did you NOT replace the system like you said your were going to do? You stated you had ordered the parts. ALSO, RUN the Fan only and see if it runs for ever without stopping in the same time frame. Hopefully you did not install the new style Freeze Thermister in place of the old Bi-Metal freeze sensor. The old Board is not capable of reading the New type Freeze Thermisters and will cause operational problems. AS to why it would work after setting. IF you have a burnt/corroded 120 wiring(nuts), it gets HOT and breaks down and when it cools it has continuity again until it gets hot again until it eventually burns apart. Doug

[Chris_Bryant]

Double and triple check the freeze sensor and room sensor to make sure they are plugged in to the correct plugs on the board.

[Kountryguy]

I did not replace the upper board or the 4 button thermostat. Yes, both the compressor and fan shut down. I think it has to be the upper panel. To my thinking, please correct me if I am wrong, if it was a bad connection it would not restart with the dependability that it does. I think it must be hooked up correctly because it worked for 2 or 3 days before this problem began.

[dougrainer]

I thought you stated previously that you replaced the Upper board and tstat with a 5 button system? Is the complete unit going dead? Both the compressor AND Fan shut off? If so, I suspect your control board is not good or set up correctly. If they shut down(both) you are losing 120 power to the unit. If you still have the original 4 button system, then I will bet you either have a LOOSE 120 wiring where they connect with wire nuts at the upper board or the control board 120 connections are bad. Doug

icing up will not stop the fan from running. Also, your model has a Freeze sensor(I hope you installed that part when changing out the AC unit.

[Kountryguy]

Thanks. I did all that.

[midnightsadie]

sounds like it might be freezing up ,you,d have to go on the roof and look at the fins see if there iced up. see if the fan is turning while your there.