Hard Start for AC

rstanek wrote:
I want to thank everyone for their imput, the unit already has a run capacitor for the compressor and fan motor, I think I will leave it at that, the AC runs fine it just starts a little hard with a generator, I think with a fan delay timer so both aren't ,starting at the same time will make the difference I am looking for. It also starts,easier when I leave the fan on all the time, An RV tech recommended that anyway so the unit is less likely to freeze up and also drys out so mildew doesn't grow on the evaporator.

Like I said delay the compressor not the fan, you don't want the compressor running without the fan.

Denny

I want to thank everyone for their imput, the unit already has a run capacitor for the compressor and fan motor, I think I will leave it at that, the AC runs fine it just starts a little hard with a generator, I think with a fan delay timer so both aren't ,starting at the same time will make the difference I am looking for. It also starts,easier when I leave the fan on all the time, An RV tech recommended that anyway so the unit is less likely to freeze up and also drys out so mildew doesn't grow on the evaporator.

This is how it works, the motor has two windings, a run and what's called a start. The run has heavier wire than the start so the start has more resistance. When power is applied to the windings the higher resistance of the start will shift the phase angle just a little starting the magnetic rotation in the stator that acks on the iron core of the rotor. When the rotor starts turning it builds inductive reactance or induced resistance, the induced resistance drops the current the motor needs.

To increase the starting touque a run cap is added to the start winding shifting the phrase a little more increasing the motors touque. The run cap is designed take the current of the start winding, when a start cap is added to the system it shifts the phase even more for more starting touque but it can't take the current for very long so so it needs a relay to take it out of the circuit after start up.

The start cap doesn't reduce the inrush current because all motors are close to a dead short at startup but it makes the high current draw shorter because the higher touque makes the motor start faster.

The manufacturer of the compressors designs the motors and decides what run and start caps and relays it needs for best operation not aftermarket suppliers so if you need to replace or add a start cap or any cap use what is recommended by the manufacturer, the timing of the start cap is very critical, staying in the circuit to long and the current draw goes up not long enough and it takes longer for the motor to come up to speed so higher current draw. Also if the start cap is in the circuit to long and it will go up in smoke.

Denny

It'd be good if you posted the full model number of the Mach 15, and a picture of the capacitor area.

On our 2002 Mach 15, a Start Kit was apparently a factory option and Jayco got it that way. Has a Relay-controlled Start Assist. RVP now says their current model Mach 15 is standard with hard start, but they use a PTCR device in place of the relay. If there's already a start kit, you can't add one on top of it.

The SUPCO SPP6 uses PTCR. The SPP6e is "electroncically controlled" and is supposed to be equivalent to an OEM Relay setup.

Here's where it gets interesting. Chris Bryant, one of our resident service tech gurus, recommends SPP6e. SUPCO recommends SPP6, and I found their explanation of why. Their tech says the "e" series will take the start assist capacitor (usually round black plastic case, 88-108 mfd) out of circuit too quickly. Not giving the generator time to react to the starting load of the A/C. That's SUPCO's position.

rstanek wrote:
Installed a Supco SPP6 hard start kit on my 2007 Coleman Mach 15000 btu AC and it didn't work, it actually did just the opposite. I overload my generator, voltage dropped to 50, not good, without the hard start voltage drops to 90 but recoups in about 1 to 2 seconds, why doesn't the hard start kit work, I've heard so many good things, hookup is easy. Any suggestions?

Are you sure the unit didn't already have a start cap? If it does adding a second one will not help but it will make it worse. I would remove the new one and live with it, some generators just can't handle the start current.

If you use a delay on start put it on the compressor not the fan motor, it will help so you don't have the start up current for two motors.

Denny

The AC works just fine with shore power, never an issue, I just want to give it a little better kick start when using my generator, i connected it according to the instructions, only two wires, connected to the compressors run cap, I am installing a timed delay module for the AC fan, the compressor will engage first, the 8 to 10 seconds later the fan engages, that way they both don't start at the same time, I had the compressor checked and it is fine, running amps at 11.5 , just what it's supposed to be, I know starting amps is more, that is what I'm trying to make easier.

Sounds like something connected wrong!

garyemunson wrote:
Hard start kits only work on utility lines where there is a virtually unlimited supply of power to give the A/C compressor that extra 'kick'. Unless you have a 20KW generator, you're going to load the hell out of it with the hard start kit.... I'd suspect the compressor is either on it's way out or there is a restriction in the refrigerant line. With a 9 year old A/C, I'd bite the bullet and replace it.

Not true. RVP(coleman) has built in Hard Start kits optioned for OEM's that install the Roof AC units where there will be either a Genset or a future Genset installed. Hard Start kits are great for smaller(less than 5k) Gensets, especially the NON RV Gensets people like to buy. Doug

Hard Start kits work with NEW compressors and older Compressors that are slightly worn and need that extra "kick" to start. IF your compressor is failing/worn out, then a Hard Start cannot fix that. Also, are you POSITIVE you installed it correctly? Doug

Sorry, I can't help with your problem.

But the SPP6E I installed on my Coleman AC about 10 years ago makes starting the compressor a breeze for my generator. My multi-meters aren't very fast, but they would display an initial drop into the 90s before the compressor fully cycled up. With the hard start, they never display below 100vac. Also, before installing the hard start, I could hear the compressor trying to start for a second or so (even on 30 amp shore power). Since the kit was installed it "appears" to start instantly. My Yamaha 2800i can now comfortably run it in economode.