Rapid ac cycling

[Clifftall]

My ac's are working great as far as cooling. I'm getting temp readings of high 50's to low 60's at the ceiling vents. The rear unit cycles back on in just a few seconds when it is set at 76 or 77. I'm not sure if it is just the fan or the compressor as well as the front unit is usally on and I can't hear. I know I could shut off the front and listen better but was just wondering if anyone else has the same situation. It seems that as soon as the temp is reached and it shuts off , the thermostat goes up one degree calling for it to turn on again. Rv products told me that the thermostat cannot not be adjusted. The front unit doesn't do this. It's an rv products unit which I think is Coleman.

Any thoughts will be appreciated.

[38 Special]

Turn off all floursent lights and ceiling fans and see if you still have the problem.

[Clifftall]

Quote:

Originally Posted by 38 Special Turn off all floursent lights and ceiling fans and see if you still have the problem.

I have't used the flourescent lights since I was made aware of the problems they cause 2 years ago and the ceiling fans are not in use when ac is on. Thanks

[RV Wizard]

Make certain the supply vent is not blowing directly on the zone thermistor and that there is not some type of heat source effecting the function of the thermistor. Even bight sunlight reflection can falsify room temperature monitoring.

[Clifftall]

Quote:

Originally Posted by RV Wizard Make certain the supply vent is not blowing directly on the zone thermistor and that there is not some type of heat source effecting the function of the thermistor. Even bight sunlight reflection can falsify room temperature monitoring.

I think you hit it Mike. There are 6 ceiling supply vents in the bedroom and FW in ther devine wisdom placed the thermistor on a wall right by the window. Now, RV Products tells me that there is a built in 3 minute delay for the compressor, so hopefully only the fans are coming on for the first 3 minutes.

Thanks
Cliff

[PapaD]

My ac seems to run only for a few seconds during the night then kicks off. I can hear the compressed kick in then just a few seconds later it kicks off. It only does this during the night, it seems to run more than enough in the day time.

Any ideas as to why?

[Clifftall]

Quote:

Originally Posted by PapaD My ac seems to run only for a few seconds during the night then kicks off. I can hear the compressed kick in then just a few seconds later it kicks off. It only does this during the night, it seems to run more than enough in the day time. Any ideas as to why?

See RC Wizards reply above. The supply vent blowing on the thermistor gives it a false reading and shuts off ac. Then the thermistor reads the correct temp and immediately calls for the ac to turn back on. I pointed my supply vents away from the thermistor and it solved my rapid cycling. Thanks again Mike.

[PapaD]

I did read RV Wizard yesterday and made sure my vents were turned away from the thermister and the thermostat. That did not help. The ac started this last year on vacation. I would get up during the night and turn down the thermostat a couple of degrees an it would run until it was satisfied. Then start over again. It does not do this during the day. Go figure. Do you know what is the function of the thermister?

[Clifftall]

Quote:

Originally Posted by PapaD I did read RV Wizard yesterday and made sure my vents were turned away from the thermister and the thermostat. That did not help. The ac started this last year on vacation. I would get up during the night and turn down the thermostat a couple of degrees an it would run until it was satisfied. Then start over again. It does not do this during the day. Go figure. Do you know what is the function of the thermister?

I think the thermistor sends a signal to the thermostat which turns the unit on and off. I'm sure someone will correct my guess if I'm wrong. As far as your situation, I would guess that the temp you set at night is on the cold side and as soon as it is reached the unit turns off and shortly after that the thermistor senses a slight rise in temp. and calls for the thermostat to turn unit back on. You may have turned the supply vents away but the cool air is still passing by the thermistor which is soon replaced by warmer air when the unit shuts off.