Someone recently asked about a hard start capacitor for their 13,500 AC unit. I shopped for one some weeks ago and ended up buying one from a local RV dealer, but I haven’t installed it yet. I will after the snow melts.
If you open the link http://www.rvcomfort.com/rvp/pdf_doc...literature.pdf
and scroll down you will see the Mach 3 13,500 AC draws 15.3 amps for cooling, so it can run safely on a 20 amp circuit. (16 amps for heating – if equipped). But when you first turn it on it draws much higher, (my model is rated to draw 33 amps) but only for a split-second
, it’s called “in-rush”. That’s common to air compressors. It’s kind of like rolling a heavy object – hard to get moving, but easier once it’s going.
So your 20 amp circuit needs to be protected from the high in-rush current. That’s usually accomplished by a delay fuse or breaker. The in-rush current won’t blow the fuse or trip the breaker because it’s manufactured not to, and the rest of the circuit is not damaged because it happens so fast.
If you are plugged into a source that can handle the bigger draw such as residential, campground, or commercial outlets, you don’t need to concern yourself with in-rush. If you are using a generator, it’s important to know it has sufficient power to supply the in-rush current. Portable generators will fail sooner-or-later when asked to provide more power than they are rated for – even momentarily.
There is no formula I’m aware of to determine what your draw will be after installing a hard start capacitor. For the model I have, it’s commonly thought to be “less than 20 amps”. I’m going to have mine checked with a clamp meter before buying a generator.
The hard start capacitor comes as a kit, and includes the capacitor, wires, PTCR switch, instructions, and a strap clamp. (The PTCR removes the capacitor from the circuit after the AC has started. In the picture, it’s already connected to the top of the capacitor.) When installed, the capacitor stands next to the “compressor run” capacitor and also connects to it. It’s held in place with the strap. The compressor run capacitor is equipped with electrical connections on its terminals to connect the hard start capacitor. You already have a strap holding your compressor and fan capacitors, so it might just need an adjustment. That’s a long way of saying take the cover off, set it in place, and plug it in.
Check first, because you might not need one. I found out there are about 20 different models in the 48000 series. Some models come equipped with a hard start capacitor.
I hope you all appreciate this. It’s a lot for a fat-fingered old man that can’t type.