Salem Hemisphere 370BL A/C Cooling Issues or larger FW dual AC trends

[larryi]

General question for members with larger fifth wheel trailers (40ft) equipped with dual ducted AC unit trailers. We have a new FW after upgrading from our smaller TT and we are finding frustrations on trying to get the bedroom 13.5k and main room 15k AC units to operate together and cannot figure out if our unit is not functioning properly or is this a general problem with larger dual AC equipped trailers?? It seems like if the trailer is hot and you run both units to get the air temp back into a comfortable range they behave together well to cool the trailer. They then stop behaving together when trying to maintain the setpoint temperature.

I have opened up both inside AC covers and foil taped the return air side from the supply side to ensure no leakage causing performance issues. This seems to helped the 15k unit from short cycling a little....but unit does not seem to run quite right.

1. Our trailer has the Dometic thermostats co-located in the main room area by the doorway. Is this common and are you able to balance air temps in your trailer with the thermostats located like this? Are people able to set both Tstats at the same temp and have them work properly or are you setting the bedroom temp at a much different setting to force the units to work together?

2. Our observation so far is that the main room 15k unit will short cycle frequently when trying to maintain the setpoint temperature. I have read that the unit does have to cycle off to change from high to low fan speed and vice versa if in auto fan mode.

3. I hear my AC unit cycle on with the compressor running but no fan running. Is this right?

4. Short cycling. Do you feel like your units short cycle alot? Do you try to set up one unit as a lead / lag thermostat setpoint? If so, how are you doing this?

Are these typical issues/frustrations with your unit? I would like to know if other trailers are able to moderate temperatures with dual AC units before I take mine back to the dealer for a warranty claim and they do nothing telling me that this is the way they are and I should just accept current performance.

Thanks in advance for your assistance.

[Bama Rambler]

If you turn the thermostats to off and press a button to check the ambient temp, do they both read the same? I'll be surprised if they do.

You may need to offset one of the thermostats in order to get the units to play nice with each other.

I'd also try and initialize the thermostats if you haven't tried that.