[Brad Townsend]

The capacitor was replaced with the new compressor and dryer. I pulled the unit out of the bay and checked the play on the shaft and there seems to be none and it does spin easily. So tried again to run the unit checking the amperage. The amperage rating on the motor specs 2.35 and it was actually pulling 3.0. Not sure if that much higher makes a difference, anyone know about that?
In about 5 minutes of run time the motor gets up to 135 degrees and just cuts off with no increase in amp draw.
The stuff on the shaft could have been done at newell in an attempt to just try something. I don't see this on the other units.

[Richard]

Brad,

Here are some points that I'm working from.

It didn't do it until Newell worked on it.
The capacitor was replaced.
The motor spins freely.

So the change was Newell worked on it. The wiring was removed and reinstalled.

Is it possible the run and start are backwards on the capacitor?

[Brad Townsend]

What would be the symptoms of reverse wiring? Remember the motor gets hotter than the other two units prior to shutting down. I could try to change wire positions but could I do any damage if I wire it backwards?

[Brad Townsend]

I have the schematic and will check to see if the wires are like in the schematic.
Good thing to check prior to my next step which is to have the motor rebuilt. Can not
find one thru Grainger or MSC. There is a company close by that advertises rebuilding motors up to 800 HP.

I have eliminated any of the items in the house box as they all relate to the evaporator nothing to do with the condenser.
There is only the one 110 house wire with a black and white and ground wire that goes from the house to the condenser unit and
there are no relays in the condenser only the capacitor.

[prairieschooner]

Brad,
Sorry I have not been on in a while so please excuse but I am trying to catch up.
I would start by proving the components individually. You are far ahead in knowing that when it fails the system shuts down appropriately.
Could you "hot wire" the Blower? I would try prove it by itself and use your amp & volt meter through the test.
Also I am sure Newell or you have done this but clean the condenser just to make sure the system is ready to run properly.
Best of luck! are you guys at the wash?

[Brad Townsend]

Hi Steve, we are back in the north east. Good to hear from you. We will back at the Wash in Nov.
The ac was blown out at newell not very dirty though. I plan on pulling the wire that connects the compressor leaving the fan to run but the one thing that keeps standing out as different from the other units is that the motor gets much hotter then shuts down.
In the last 2 days I have had to RV techs say the motor has a thermo switch built in ans it is doing it's job because of the heat.
They say to replace it. Even if I found and replaced the thermo switch it probably wouldn't fix the problem as it is about the motor getting over heated. So what is causing the over heating. I may just have the motor rebuilt if I can't find another replacement.

[Fulltiming]

Brad, I have had two condenser motors rebuilt in Austin since I couldn't find a replacement for the motors in my Dometic basement AC units. After you have verified that the capacitors are wired in correctly, I would look for a local motor rebuild company. They may be able to test your capacitors to make sure they are functioning properly. Many AC issues are solved by replacing bad capacitors. Even new capacitors can fail.

[Brad Townsend]

Thanks Michael.
How can I check the capacitor to verify it works. it was replaced at newell and the tech there said it either works or it don't.
But would a bad capacitor cause the motor to run hot?

Brad

[Fulltiming]

A capacitor can lose strength (capacitance) although they typically just fail. A bad capacitor can prevent a compressor from starting. A bad fan capacitor can result in higher amperage usage which can cause excess heat.

My Dometic AC units use a dual capacitor which is 2 microfarads / 20 microfarads. This dual capacitor has three sets of connections HERM, FAN and COM. The HERM connects t the compressor, the FAN to the condenser fan motor and the COM to the contactor and provides power to the capacitor. On mine, the brown wire goes to one side of the FAN connector, the Large Red wire and the small red wire to the HERM and the Big Yellow wire, Cream wire and small white wire to the COM. NOTE: a charged capacitor can get your attention (shock you) if you touch the wrong terminals. There are ways to test a capacitor but you must have a multi meter that has a setting for MFD and an adequate test range. My Craftsman Professional model 73756 does but most of my others don't. Remove the leads, attach one lead to the Fan connector and one to the COM connector and is should read at least 2 micro farads. Then test between the COM and the HERM and it should read at least 20 micro farads. It is possible that you have two separate capacitors but mine has a single dual capacitor and that is what the wiring diagram shows.

[prairieschooner]

In the last 2 days I have had to RV techs say the motor has a thermo switch built in ans it is doing it's job because of the heat.
They say to replace it. Even if I found and replaced the thermo switch it probably wouldn't fix the problem as it is about the motor getting over heated. So what is causing the over heating. I may just have the motor rebuilt if I can't find another replacement.

This makes total sense to me and that is why I suggested bypassing the circuit board & testing it by itself.
Things just wear out...but if something has or is going wrong inside of the motor then....
The Thermo Switch can also wear out and by itself be an issue.
You may be able to save yourself some time & money but powering up the blower with an extension cord plugged into a separate circuit and you could prove/disprove the blower using a Volt Meter and Amp Meter.
As a side I found one of my A/C Units to have a bad Circuit Breaker a few years ago (they re roof mounted though). The problem was most likely because the connections were loose as Richard indicated previously, I tried tightening the terminals but the damage was already done.