Low amperage to one A/C - Printable Version
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RE: Low amperage to one A/C - Chester Stone - 11-24-2016
Richard, the voltage coming into the control board is 125 volts for both compressors. The voltage leaving the board and going to the capacitors (compressors) is 123 volts for both compressors. Thus no 240 volts. I also rechecked the thermostat wiring in the coach and it is connected as instructed by Newell when I purchased the new thermostats a few years ago. My limited manuals give me no clue as to what to check next. Any ideas as to how compressor one draws under 5 amps?
RE: Low amperage to one A/C - Chester Stone - 11-24-2016
I followed Bill Johnson's lead and downloaded Ozarkguy's Service Manual posted on July 14, 2014 which I did not have in my computer. Perhaps I should do some of the testing shown in the Service Manual.
RE: Low amperage to one A/C - Richard - 11-24-2016
Chester,
The only way I know that compressor draws five amps is the charge is low or gone in loop one. I just don't have another explanation.
RE: Low amperage to one A/C - 77newell - 11-24-2016
There is only one way that low current can occur as you have described it as far as I know and that is that the circuit with low current has higher resistance. This could be verified by checking the resistance in each of the compressor circuits. I would expect low current circuit to have about double the resistance of the high current circuit. If this proves to be the case, then the question is where is the additional resistance located. It would probably prove easier to track the voltage drop across the various parts of the circuit. If the drop is pretty much all in the compressor that will be the undoing of the motor.
With my brain in a state of turkey oversaturation it is possible that I've completely missed or misunderstood some of the previous discussion.
RE: Low amperage to one A/C - Richard - 11-25-2016
You also have a really unusual problem that nothing comes on when the low circuit is on and the compressors are in their original wiring,but switching the compressor wiring causes the unit to activate in low mode. The thermostat is not the first place I would look since the thermostat wiring doesn't explain the phenom.
At this point I would disconnect the leads for both the inside and outside fan, set the tstat on low and measure the voltage at the board going to the fans, then set the tstat on high and measure again. If the voltage works like it is supposed to then you may have a wiring problem to the fans. If the voltage is not responding as it should then you probably have a board problem.
Is this the unit I which the fan motor was replaced a few years ago? Has this unit ever been serviced while you have owned the coach? Did this low setting behavior coincide with the installation of the tstat?
RE: Low amperage to one A/C - Richard - 11-25-2016
If you really really wanted to see if the low amperage was the compressor or the board, you could run this test. Make some temporary jumpers and run each compressor straight from the 120 source total by passing the board. Measure the amperage.
RE: Low amperage to one A/C - Chester Stone - 11-25-2016
I am going to work on this some today, but I question if there is any problem with the compressor circuit since both compressors draw full amperage when the connecting lines are switched, and just as the high amperage switches between compressors, so does the low amperage. This is not the unit that I had to replace the fan motor, and the low fan issue has existed since I replaced the thermostat, but I was not aware of the low amperage until I tested it recently. I will check to see if the Y1 and Y2 thermostat wires are switched in the control panel, and if so, that would account for the low fan speed working when the compressor wires are switched. Keep giving me your thoughts because I am at a loss to figure this out. I may have to send the control panel off to have it reconditioned again.
RE: Low amperage to one A/C - folivier - 11-25-2016
Chester, what is temp of the air coming out of the vent when only the compressor in question is running?
And how does this compare with the others?
And are you near one of the vortexes in Sedona?
RE: Low amperage to one A/C - Chester Stone - 11-25-2016
Forest, that is a good question and I will try to find out today.
RE: Low amperage to one A/C - Richard - 11-25-2016
Just for grins, you could switch boards between the two units to see if the problem follows the board.
If you do take the board out. Look carefully at the backside for any hot spots, especially leading from the power in connectors to the compressor relay.
I can't wait till you figure this one out, I am very curious as to the problem. I studied the schematic this morning and read the manuals several times. I am not smart enough to noodle through the schematic and figure out why switching the leads to the compressors would have any effect on why the fans don't come on.
There is a bit of logic in the board, that the compressor will not turn on under two circumstances. One, if the condensor and evap fans are not running. Two, three minute shutdown after power down to prevent starting the compressor against a high head pressure. I just don't know how that figures into your situation.