Roadtrek 190 a/c replacement

you may or may not need a hard start capacitor. however the only way to know for sure is to try it with the generator

So what will happen if I start it and I needed a hard start capacitor? Will it damage the a/c?

Since you're replacing your failed unit with a "household" unit, were it me, I'd "try it" before I installed it.

To "try it" means two ways - shore power and genset power.

First, put the A/C on a table, plug it into house power (i.e., the same as shore power) and confirm that the A/C works as you expect.

If it does, then unplug your "B" from shore power, if it's plugged in; start your genset and plug your "new" A/C into an available outlet on your "B"; and turn on your A/C and confirm that it works. If it starts, you likely won't need a "hard start" capacitor. If it doesn't, then putting one in line will likely be required. If it does require a capacitor, then you'll know as your genset will conk out trying to start the A/C. It'll begin to start it, in all likelihood, but won't quite make it and die.

Turn the A/C off, restart the genset, and try the A/C again. If the same result, then you'll know.

While your "new" A/C is a different BTU capacity than your failed one, if your failed A/C's hard start capacitor is outside the unit, then you may be able to reuse it - I'd talk with Roadtrek about that. If you can't reuse it, while they may not tell you what your "new" unit requires, they may tell you what the specs are/were for the capacitor on the failed unit. The two will be similar I'd bet. Not identical maybe, but similar.

A little testing and a little homework may get you a solution.

Cheers.

aarnold wrote:
So what will happen if I start it and I needed a hard start capacitor? Will it damage the a/c?

what hard start capicitors do is enable a lower wattage source to start an air conditioner on the starting surge which is much greater than normal running requirements. More modern rv air conditioners have this already built in. household air conditioners have more than adequate power supplies so it is not an issue. a 2800 watt Onan may not be able to give enough surge watts to start an air conditioner without the capacitor.

some time yes /sometimes no. also the higher elevation you are the less powerful the Onan generator.

what will start at sea level sometimes will not start at higher elevations.

Thanks, Retraite.
So, it sounds like the hard start capacitor stores power and then uses it to start the a/c rather than overloading the genset. Forgive my lack of electrical expertise. I was thinking maybe the capacitor might somehow protect the a/c. The RoadTrek rep told me there is probably a hard start capacitor already in the new a/c, but he recommended either using the one in the Fedders, or buying another like it ($10 on ebay for an identical/same brand). From what you say, it sounds like I can't hurt either the a/c or the genset by doing the experiment you suggest.
Thanks!

I changed mine with a Kenmore 8000 btu unit. I didn't need a hard start capacitor. The unit already has a capacitor inside it for the compressor and fan. Mine works great. Didn't do any modifications to the inside at all. My old Fedders didn't have anything special added to it.
Been 3 years now. Working fine
It was a difficult job for me though. Took me several days to get the old unit out and the new one in, all situated and mounted securely.
I do recommend bench testing the unit on the generator before installing it.

Is the Fedders a heat pump like the Cool Kat that is now used on the Roadtrek?

My 2010 Roadtrek with the Cool Kat seems to have the same problem - when set to cooling sometimes it seems to blow cool but not cold air. I finally isolated the problem (sort of) to the thermostat setting. If the thermostat isn't set cold enough to cause the unit to switch from heat mode to cool mode it doesn't blow cold air. If I set the thermostat down real low and turn on the A/C it will kick into cold cooling mode. After that I can set the thermostat to any temp I like and it blows cold air whenever it cycles back on.

It may be that the reversing valve in the unit isn't switching on the selection of A/C or heat but on the temperature difference measured someplace. Setting the temp down real low appears to be enough to get the unit to kick into cooling mode.

My old (2000) Fedders isn't a heat pump, only an A/C. I have a separate LP gas heater which I never use (I bought an electric ceramic heater). The RT guys said that they modified the Fedders in 2 ways prior to installation: (1) added rubber clamps to give extra support to the compressor so it doesn't bounce around and stress the joints in the freon pipes, and (2) added a hard start condenser.
KMB1966 -- thanks for the tip on Kenmore. I'll look into that brand for size. I bought an LG that will fit, but it is only 6000 btu. I haven't opened it up or voided the warranty yet, so I can return it to Home Depot if the Kenmore is still available.

I have a 2001 RT 190P. Replaced the failed Fedders with a LG from home depot. It has been running perfectly for the past 4 years. It is plenty enough to cool the RT on the hottest day. Just have to block the windows with silverback bubble insulation. When you install the new unit, be sure to tilt it slightly toward the back, otherwise the water from the unit will overflow and leak into the motorhome.

Your Onan 2800 should run a 11,000 BTU AC without a problem, and without a soft start, also called hard start, capacitor. It's simple to add one though.
A good rule of thumb is to double the BTU's to see what the gen-set will run. So a 11,000 BTU doubled is 22,000 so still under the 2800 watt Onan.
I would go as big as I could, at least an 8,000 BTU, especially living in Florida. A 6,000 BTU AC isn't going to do much when temps are over 85 degrees.