I am renovating a 1988 TravelMaster (now Coachman) Ford E350. When I run the AC connected to outside power, the AC runs for maybe 10 minutes and trips out. The last time I tried using it I smelt electrical wires getting hot. I shut it down and the electrical panel was very warm.I just got the 4K onan generator working for the first time. I thought I'd try the AC and it works fine. And the electronic control panel and wires were all nice and cool. So the AC problem I thought I had is gone.I assume it is the transfer switch.I am not familiar with a transfer switch operation. Not sure if this is normal. When I turn on the generator (not connected to shore power), it seems like it takes about a minute or two to switch over to the generator power. I watch the power light on the microwave, and it does not light up until there is a click which like I said is a minute or two. I imagine this is normal but thought it would be worth mentioning.Thanks for reading. Any thoughts as to why the AC trips out on shore power are appreciated.

You didn't say what you were pluging into when on shore power. If you are using an adaptor to plug into a regular household outlet, there is you problem If you are using an extension cord after the adaptor, definity your problem. You need to plug into a 30amp outlet.

How heavy and long is the cord that you are using to plug into shore power?You might have a voltage drop.Use a volt meter to check the voltage when running the generator, and when on shore power.

I am not using an extension cord(I learned that about a year ago). I was plugging directly into the campsite power. At my house, I created a 30amp circuit running 10 weight wire. It tripped on that.The the big ass cord (30amp rated) is 25 feet long.Dusty R, when you say check for voltage, would that be inside the rig where the wires connect to the AC unit?

I doubt you've owned this 30-YOA unit since new, so you don't know who's been tinkering, or what may have been ignored. The Shore Tie Power and the Generator Power both wind up in the Panel, but they follow slightly different paths. So YES, inspect Transfer Switch and its connections. Actually surprised a 1988 Class C even has one. With many that age, "transfer" happened by plugging the Shore Tie Cable into a Pedestal-Type receptacle powered by the Generator. So your TS may have been a modification, and quality of installation becomes suspect.Uncover your Panel and tighten every terminal screw. Often, the flexible Shore Tie Cable is spliced into "hard wire" where it enters the coach. Find that box, or whatever it is that connects Shore to Coach, and make sure those connections are good.

How does the end of your shore power cord look - any issues? How about the outlet itself ? Are the wires in the outlet box and your house breaker box secured ?

AC trips out on shore power but not when on the generator

12 Replies

DrewE
Explorer II
Jun 07, 2018
wolfe10 wrote:

Sorry, I am confused. If the shore power cord is wired directly to the ATS, the wires should be secured directly to the lugs in the ATS.

Where is this "wire nut" connection located?

I believe that depends on the ATS model. My motorhome has an ATS that has permanent pigtails that are wire nutted to the appropriate input and output wires. Other designs have lugs that the wires are secured to rather than pigtails.
j-d
Explorer II
Jun 06, 2018
Good job. Glad we didn't go off the deep end on this.

For the plug on shore tie, I replaced the steel screws with stainless, and was able to corral the strands using the washers that sometimes show up on water heater timers, heater elements, etc. It's a cupped washer that holds things together. The shore tie I fixed that way stayed cool.
heyobie
Explorer
Jun 06, 2018
I was able to move the RV near my 30Amp outlet and plugged in. I ran the AC for 1 hour without incident. The wires were all nice and cool and the AC was running strong.

Thank you guys for the help. What I thought was a complex problem was really very simple. I just needed a little help from some smart experienced people.

Wolfe10, in this ATS, the shore and generator wires enter a metal box and are wire-nutted to the appropriate wires in the switch. The ATS wires drop down into a hole in which I can not access. The box is riveted together. You probably have not see one this old. It has a date on it of 11/88.
wolfe10
Explorer
Jun 06, 2018
heyobie wrote:
I had tightened all the connections before the last test. Everything looks clean at the panel. The power chord goes directly to the ATS. Removed the wire nuts and all looked good.

Sorry, I am confused. If the shore power cord is wired directly to the ATS, the wires should be secured directly to the lugs in the ATS.

Where is this "wire nut" connection located?
heyobie
Explorer
Jun 06, 2018
I had tightened all the connections before the last test. Everything looks clean at the panel. The power chord goes directly to the ATS. Removed the wire nuts and all looked good.

I went to the plug end of the power cord and took the plug apart. ALL 3 wires were LOOSE and some corrosion on the ground and white wire. The wire is stranded copper and half of the strands could not fit under the screw because the wire is so large. I cut all the wires and started over. Sprayed and sanded the spades with electronic cleaner and soldered the strands together and then soldered to the spades. Good contact now.

I need a couple days to test because the front end is up on blocks and I can not get close to my 30amp outlet. Replacing the calipers and bearings. Will report back but I think this is the problem.
j-d
Explorer II
Jun 06, 2018
I should have asked. When you said "...AC runs for maybe 10 minutes and trips out..." just WHAT is tripping? What has to happen before it'll run again?
wolfe10
Explorer
Jun 06, 2018
You can check voltage at any regular house-style outlet in the coach.

With 30 amp, there is a single hot, so A/C and outlet voltage will be the same.

Also, with shore power disconnected, generator off and inverter off if you have one, open the ATS and check that all connections are clean and tight. Could have a problem there, at the male or female end of the shore power cord or the connections between side of coach and ATS (if the shore power cord doesn't connect directly to the ATS).
Mich_F
Explorer
Jun 06, 2018
How does the end of your shore power cord look - any issues? How about the outlet itself ? Are the wires in the outlet box and your house breaker box secured ?
j-d
Explorer II
Jun 06, 2018
I doubt you've owned this 30-YOA unit since new, so you don't know who's been tinkering, or what may have been ignored.

The Shore Tie Power and the Generator Power both wind up in the Panel, but they follow slightly different paths.

So YES, inspect Transfer Switch and its connections. Actually surprised a 1988 Class C even has one. With many that age, "transfer" happened by plugging the Shore Tie Cable into a Pedestal-Type receptacle powered by the Generator. So your TS may have been a modification, and quality of installation becomes suspect.

Uncover your Panel and tighten every terminal screw.

Often, the flexible Shore Tie Cable is spliced into "hard wire" where it enters the coach. Find that box, or whatever it is that connects Shore to Coach, and make sure those connections are good.
heyobie
Explorer
Jun 06, 2018
I am not using an extension cord(I learned that about a year ago). I was plugging directly into the campsite power. At my house, I created a 30amp circuit running 10 weight wire. It tripped on that.

The the big ass cord (30amp rated) is 25 feet long.

Dusty R, when you say check for voltage, would that be inside the rig where the wires connect to the AC unit?