You all will flip on this! My next door neighbor took the rooftop AC unit off his old motorhome and installed in the attic of his house to cool his garage, it actually work very well but he said the plug that's plugged into the 110v outlet gets hot but it doesn't seem to bother him! Well it bothers me, it shouldn't be getting hot in the first place so did he wire it wrong or are those moho rooftop AC units not compatible with home wiring?

 

Welcome to the forums! PT Barnum said it best. What are the specifics on the nameplate of the AC unit? Voltage, etc. Of course a Mobile Home AC is not adaptable to a residence. Let us know the nameplate stuff and we'll try to help.

 

He thinks it's a Copelaweld, it's off his 25' 1977 Dodge Pace-Arrow moho. For some reason he doesn't know how the controls, (2 potentiometers), were originally wired! I've looked online for wiring diagrams but had no luck! I heard something about the grounds on 110v moho wiring is different from home 110v wiring? I don't know!

 

Very confusing. till you check on line and find that most RV roof top ACs run on shore power or a generator. They are not DC so they should work fine. However the AC cord he is using may be too small thus the heat at the plug.

 

Ok, potentiometers was the wrong word to use, the 2 (dials) that control the AC unit are not marked! One dial is a 4, 5 or 6 position switch and the other is a one is what I'm assuming could only be a temperature dial, it only turns right to left and left to right, kinda like warm/cool/cold and back down cold/cool/warm if that makes any since?

 

The internal connections to the plug may be loose or the unit may be pulling too much power.

 

I'm thinking it may be pulling to much power because he said the wire runs basically the length of his house! Would't that create a voltage drop situation? To where it's staving for power so the cable gets hot?

 

If it does need more power and the cable keeps getting hot, what are the risk of him leaving it that way? Yes, I know fire or damage to the AC unit but can that cable get hot for years without causing any problems? I have a Ultracool swamp cooler on wheels in my garage, much simpler and it works great, as it's pointed right at me, lol!

 

I have had a couple of motor homes and it seems to me that the rooftop air units draw about 14 amps. The two controls on the unit are probably for (1.) off, fan, high cool, low cool; (2) Temperature thermostat control. More than likely the plug getting hot is an indication of poor physical contact in the outlet/plug connection. Put a brand new plug on the line cord of 20A rating and check to see if the outlet he is using has a good stiff connection when plugged in or if it is loose and very easy to insert the plug. He may have to put in a 20A rated outlet also. Wouldn't hurt to do a line voltage check with unit running to see if the long run is dropping the voltage at the outlet.

 

How does he do check for voltage drop while the unit is running? It blows cold are so I'm assuming hes got it wired right, could a crossed wire at the unit cause this problem?

 

Electrical concerns aside, I don't think a motorhome A/C unit installed in the attic, especially in Arizona, is going to work very well or last long! An attic in the summer, especially in AZ, will be extremely hot. The A/C unit will develop very high head pressures operating in this super-heated atmosphere and as a result, cooling capacity will suffer, as will the life of the compressor. That A/C unit needs to be in an area of good ventilation, preferabily outdoors, to work as designed.

 

Yes I agree 100%, that's common sense but it's not my garage, I just want him to do it right so he doesn't burn down his and my houses!

 

it needs a good cleaning? That turned out to be the answer for another member here a month or so ago.