Mach 8 AC Shutting Off

jsk · 05-02-2019, 04:16 PM

We have a 2017 NP. Since it warmed up this week I turned the ac on. It ran for a long while before I went inside. The next day I come home and only the fan is running. I mess with thermostat and nothing. On the thermostat I cycle it to off and back to auto cool hi and it comes back on. This is the pattern. When it is not running I cycle the thermostat and it starts running. The only other items on are the residential fridge and inverter and I am hooked up to 30a.

I did take covers off and both fans are free flowing and the air is very cool when running.

What are any thoughts? I am hoping a capacitor but do not understand why it works when turning off and back on with thermostat unless it is resetting something.

Thanks for any help

ALJO · 05-02-2019, 04:29 PM

The compressor will run when it is ready to run, not if you feel like it. The compressor will not start against high pressure until till it is lowered. So just let the A/C go through its own cycle.

jsk · 05-02-2019, 05:53 PM

Sorry-maybe I did not explain myself very well. If thermostat says it is 90 and thermostat is set at 80 you can turn the ac on and it will run. At some point the compressor quits cycling and only the fan runs. At that point you can cycle thermostat to off and back to auto cool and it will run as normal.

For example today thermostat was set at 82 but was reading 90. The fan was running but compressor had not been on for a while (long enough that all the condensation had dried up). I cycle thermostat to off and then on and everything works as normal and it cools. It will run for some period of time and the same thing happens again.

jsk · 06-02-2019, 08:41 AM

Still looking some help. I took it to RV repair guy who kept it for 2 weeks and could not duplicate problem. Unit has run fine until yesterday. Until then it has cycled on and off like the other ac even in 100 deg temps. Yesterday I walked in and only squirrel cage fan running. Thermostat set at 78 and was reading 82 so it should be cooling and was not. Neither the compressor or fan were running. While in a failed state I checked voltages. The control board had 12v at the cooling spade (don’t remember letter). The purple wire and black both had 120v. At the plug that goes to the electrical box there is 120v. When I plug the connector plug back in the fan and compressor come on for a split second and go off. Today I intend to get in the electrical box where capacitor is and check some more.
I turned it off and shut breaker off for the night. When checking this morning on auto hi cool only the squirrel cage fan comes on.

At this point something has finally failed it has just taken it a while. I am inclined to think a slow failing capacitor.

Any other thoughts or ideas are appreciated.

Thanks

Chris Wendt · 06-02-2019, 09:43 AM

I had the same problem two different times.

1. The divider between supply and return was loose and allowing cold air into the return then the sensor would detect cold air and shut down.

2. The sensor came loose

Take off the plastic trim inside and check both of these things.

jsk · 06-02-2019, 01:16 PM

Quote:

Originally Posted by Chris Wendt

I had the same problem two different times.

1. The divider between supply and return was loose and allowing cold air into the return then the sensor would detect cold air and shut down.

2. The sensor came loose

Take off the plastic trim inside and check both of these things.

Are you referring to the freeze sensor? If so it is in place in the fin. The divider is in place also.

I am looking at capacitor but have not tested yet.

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