another a/c question

[kimbo1]

I have a 2007 39v Discovery m/h with 2 h/p on top.

Question: h/p in rear when running and has not reached temp will sometimes shut down and then starts up after 5>10 sec? This a/c is 2 months old, compressor went out on old unit, but old unit did same thing. Any idea's?

[kimbo1]

thanks for the replies. I have been Hvac teck for 10 years, still learning! I have checked volt 119 > 120 steady both lines (50amp) will drop to 115 volts with dryer, elec. water heater, microwave 2 a/c running. ran line meter all night and day never got below 116 volts. a/c shut off and on 3 times last night. dougrainer may have answer, this afternoon I saw termostate go blank and the unit cut off. I think I may have a sensor problem.

[SeaDog_BRR]

I think Golden Hvac hit it right on the nose. I burned up my front AC years ago by running a to small extension cord from my house and attempting to run the ac. It did the similar thing cycling (because of low voltage high amperage) until the compressor went south. Good luck

[dougrainer]

Since the OLD unit did the same thing, I would check the Temp remote sensor location. What brand HP do you have? RVP or Dometic. Doug

[Golden_HVAC]

IT sounds like the old unit went out because it was turned off and back on to frequently by the control system.

What is your voltage? You should have at least 106 volts, or I would leave it off. It might be the compressor is shutting off due to low voltage and high amperage, this will trip a internal high winding temperature overload, and stop the compressor while the thermostat is still calling for cooling. After 10 - 20 seconds, then the high temp overload automatically resets, allowing power to the compressor, however it might not start due to high pressure difference between the cold and hot side Freon temperatures and pressures. It might take about 2 minutes for the pressure to equalize.

It is something that needs to be checked very soon! Or you will be replacing another compressor or unit.

You can buy a "Kill-A-Watt" on e-bay for about $20. It plugs into a receptacle, such as the kitchen or near the dinette, and you can monitor the voltage. If you regularly see voltage below 110 volts, then that will explain the compressor failure.

If you camp in 30 amp campgrounds, then a Hughes Autoformer will solve the low voltage problem by boosting the voltage by about 12 volts when required. It will monitor the incoming voltage, and has a 12 volt booster transformer, that will correct the voltage in most situations.

If you are in a RV park that is 50 amps and still has low voltage, ask for another site, or they make a 50 amp version of the Hughes transformers. Usually 50 amp parks are wired with larger wires, and do not suffer from such low voltage, but it can happen.

Fred.