Onan 5500 Issues

[wildebill308]

5 hours ago, manholt said:

FIVE.  16 ounces. $8.95, treats 16 gal. of gas or diesel fuel.  You and me, about 9 cans each, $81 + Tax.  There are other products out there, like Lucas.

Carl

Why do you think I was advocating using the alternate fuel supply AKA the five gal gas can. That way you don't have to spend on enough to treat the main tank. In your case to get the same ratio as a can in 5 gal it would cost you $243.00 + tax.

Bill 

[manholt]

ziggyh.  Thank you for this very useful information.  There are so many things that may be common knowledge to some, but a new thing to me!  Really appreciate the picture and description that you provided !

Carl

[kaypsmith]

You will not need to use 5 gallons, 1 or 2 will do just fine for test run and carb cleaner purposes, the main issue is to get another fuel supply hose into the picture. I have seen many times that an old fuel hose caused the same issues that you are having. You may very well be having hard start issues, but I still think that the genset should not be bogging down enough to shut power off.

[manholt]

Agree!  Since you changed out plug's, filter etc. the gen should be good to go, unless you have gunk somewhere within the system and mostly as Kay said

, it's the line!

[oneway]

Update:

Sorry for the delay, but I pinched a nerve in my back and I've been a few days on Aleeve just to get up on the roof. I went up today because as I said I found the rear A/C not starting.

So here we go:

I took off the shroud and found the start capacitor with obvious trauma. The capacitor is a Mallory 88-108MFD 165VAC. It had a small plate about 1/2" square that was attached to one of the spades on the red wire and the other end to the capacitor. That plate was completely apart so I knew I was on to at least something. I went to the local RV parts store and bought the same part # but the new one had a resistor (I think) bridged between the 2 terminals. The parts guy thought it was to take the place of the plate I described. I put it in and plugged the coach back in.

upon attempting to start the rear A/C on shore power the new capacitor promptly blew. So I'm on to something here. I just don't have enough knowledge to know what.

All I'm certain of so far is that I don't want either of the first 2 technicians back here. I need to find out why I'm blowing start capacitors. Then I'll bet my gen set runs both A/C's.

Input????

[wildebill308]

Did  you use/add a "hard start " capacitor? I would test the compressor to see if it is ok. I hate to be negative but it might be the compressor going bad.

Bill

[oneway]

How would I test the compressor? I did not add a hard start capacitor. I simply replaced the capacitor with the new one.

[wildebill308]

I would look online for information based on the make and model of the compressor. If I remember there is a range of voltage drop. I will bet you need the start capacitor to troubleshoot it. But look maybe not.

Bill 

[oneway]

Last update for now.

I don't think I'm gonna climb back up and change out another start capacitor just to watch it blow again. And I don't have the tools  to check voltage, etc.

current plan is to live with the 1 A/C and if it gets too hot I'll head for home. I can give up the RV to the shop for a month or 2 when I'm home in April without issue. The next scheduled outing is in August.

That should give the shop time to diagnose and repair everything, and me time to lick my wounds from the bill.

ill try to post the results so if anyone else gets in this spot they'll have an idea how to proceed.

thanks

[hermanmullins]

Nice report, let us know what the shop discovered. Safe travels till then. 

Herman 

[oneway]

On 2/20/2017 at 6:26 PM, ziggyh said:

The start cap is easy to replace, many AC units also have a PTC or timer relay.  In the case of the PTC they usually burn up and need to be replaced.  They usually come as a kit and some manufactures call them a hard start kit.  They usually burn up when the line voltage dips down to about 104 volts.  The condenser fan will run but the compressor will no start ,just hums and draws high Amps till the therminal protection cuts out.  Some times you can smell a burning smell when they fail.  When you remove the cover for the electrical connections where the capacitor is you may find 3 capacitors, 1 start, 1 run and one for the condenser fan.  Sometimes the start and run capacitor is one unit and will have 3 terminals on it instead of 2.  The burnt PTC and capacitor is usually easy to spot.  I would buy a second kit if you have 2 AC units, mine failed with in a year of each other and I now carry a spair.  They can be purchased for some units from camping world or RV parts supply as well as from  electrical motor repair places.  The last option is usually the cheapest.

Update to the update, update:

i went to the RV supply store and talked to a different guy. He showed me this exact part. Bear with me because this is a learning experience for me.....

the capacitor they previously sold me did not have the PTR shown here. Now I understand as I put 2 and 2 together what it was that I observed when I described the plates I found burnt. They were inside the plastic housing shown here attached to the red wire.

so I now have purchased this exact start kit and have a technician scheduled to come check out the unit to prevent me from smoke testing another $35 part.

stay tuned. Tuesday is Tech day.

my thanks to Ziggyh for a spot on explanation with photos. I'm gonna try to attach some photos as well so you can see what it looks like from my end.

[oneway]

Here you can see what I found initially. Clearly the plates have burnt and separated and I only found some plastic pieces. Now I know that these plates are inside that PTR.

remeber, the parts guy just sold me a replacement capacitor with a resistor soldered between the 2 spades on the capacitor. It did not have the PTR on it.

stay tuned

[ziggyh]

The ptc is what needs to be replaced with the start cap. The burnt part is the ptc.  From the picture it looks like you have Coleman Mach series of AC unit. You should always replace them as a set in my mind.  

[oneway]

I have the correct part in hand. I'm just gonna let a tech do it since he can appropriately check to see if there are other problems as well.

the parts guy gave me a replacement capacitor without the PTR/PTC. (Whichever it is.) on the initial replacement. I just don't want to blow this one as well.

and yes, it's a Coleman Mach III

and by replacing the set you mean on the front A/C as well? Or a set meaning all the capacitors in the bad A/C?

[ziggyh]

Replace the Ptc and the start capacitor as a set.  Usually fixes the problem.  The run capacitor usually don't fail that often.  If you have an electric motor repair shop near buy, they can usually measure the fan run and compressor run capacitors if you remove them and bring them to them.  Besides capacitors shorting and blowing there case open which is obvious to see, they can also dry up and loose there capacitance so measuring them is the next best way to tell if they are bad.  The run capacitors usually cost 8-12 dollars from a electrical motor supply/repair shop.

[oneway]

Here's the latest:

Had tech # 3 here today. I went up on the roof with him and watched as he heckled the resistance of the compressor.

He unplugged the red, white, and black wires. He checked the resistance between 2 of them ( don't recall which color), then he says the resistance between the other 2 should be double what the previous reading was.....which it was NOT.

Then he declared my A/C bad and went off to find out how much a replacement unit is.

Will find out in the morning.

Anybody know the testing procedure for the compressor? Did he do it right?

[hermanmullins]

oneway,

Sorry, what the tech told you would be as clear as Norwegian to me. I would not  be able to confirm his statement one way or the other. You might have a second tech look at it. If he comes up with the same conclusion as the first, compare their prices.

Herman  

[jleamont]

oneway, I cant chime in on if he did it correct or not. I will say I had a Dometic unit (non heat pump type) starting to fail before (grinding sound from the compressor) and I upgraded to a 15,000 btu unit for $550.00 in parts, (bought it at PPL motorhomes in TX had it shipped to PA) took me 30-45 minutes to install myself. Before throwing good money at the old one I figured it was my best bet as the unit at the time was 16 years old.

[hermanmullins]

I think the we may have strayed off the OP, Onan 5500 Issue.  

Herman

[kaypsmith]

Roof air conditioners on ebay start at about $475.00, some but not many have free shipping, and not hard to replace if you can get someone with a loader or fork lift to lift it to the roof. I have used a winch on a makeshift gin pole attached to the back ladder before. Yes Herman we have strayed, and I was wondering what had happened with the loading of the engine.

[oneway]

While it's interesting to see where this hads led, there really hasn't been any straying from trying to figure out why the Genset bogs down when trying to start a second A/C. I've been led all over by 3 techs, that's for sure.

I've come back to this forum each time to recap and see if any of them are on the right track. I'm not a technician so I need advice.

tech # 1 says it bogs down because the gen set needs a complete removal and rebuild.

tech # 2 says it bogs down because because the gen set needs a new carb.

after advice on this forum I checked and found the rear A/C wasn't starting on shore power as well (neither of the first 2 techs figured this out). Plus I found a blown start Cap on the rear air. (Techs didn't find that either).

I replaced the start cap (with what the parts guy gave me when I took the old one in), and it blew the new start cap that may not have been the correct one. So I called tech # 3 who:

checked the resistance on the rear A/C and declared it dead. (BTW, I had to show tech # 3 where the capacitors were on the A/C unit. He was clearly unfamiliar.)

now.....

im still trying to figure out why the gen set bogs down when I try to start the second A/C.

but I have to follow where the road leads.

so far it has led here. I have little faith in the techs at this point.

 

[kaypsmith]

Thanks for that update. One thing to try to rule out the AC, leave this AC out of the picture and make sure it is the same circuit as the rear AC, plug in a 1500 watt electric heater, turn on full 1500, that's 12.5 amps @ 120 volts, very close to the amp draw of a 13.5 AC at startup. If the genset bogs in this condition, that will indicate that there is still a problem with the generator. But you are still having a condition with the AC apparently, and I will stick with my opinion that if you are handy, a replacement of the AC will be the cheapest route to go for several reasons, one being that the newer units actually cool better and the seer is higher than the older ones, meaning less load on the generator first, and also leaving more energy available for other appliances in your coach. I mentioned in an earlier post about pricing on ebay (rv air conditioners), so you can use it as a guideline to make sure that you are not being ripped off by another technician, and also if you decide to have a tech do the replacement, you can have that person give an estimate just to swap it out. Good luck whichever way you decide to go. By the way, the AC's, when ordered can be shipped to the nearest truck terminal and picked up there, eleminating the need for having to use a home address, just use the park address and your cell #. I misstated that seer is lower, it is actually higher, I edited the post to correct that mistake. The higher the seer, the more efficient the unit is.

[jleamont]

Oneway, I would follow Kay's advice, this will insure its not the generator. Sounds like the amperage draw on the A/C might be the generator problem, but you will need to try the heater approach first to be certain.

[oneway]

I don't have a heater with me. I do have one at home, not sure the watts.

is there a combination I can try here with 1 A/C and say the electric H20 element along with Microwave?

[kaypsmith]

One will need to know the amp draw of the device in order to know if that unit is compatible or not, that's why I recommend a heater. If your wife has a hair dryer, that can be set to high if it draws enough watts, some of them have the draw marked on them for each setting size. To calculate amperage at 120 volt, simply divide the number of watts by 120, the results is the amp draw. If in a campground, I would bet that a neighbor has one, ask if that person would plug it up for your test, it will not hurt their heater, it just will refuse to glow bright red when the generator starts to bog. Yes you can put several devices together to equal the top number of amps. I used to use 300 watt light bulbs to trouble shoot a circuit in a shorted device, plugged just ahead of the questionable device, it will glow bright, then removing one component of that device at a time until I found the faulty component, at which time the light will glow dim. To answer a question earlier about the tech checking resistance, if he used his test leads correctly on the compressor and found zero resistance, that would clearly indicate a shorted compressor, which means that it would do nothing but trip any breaker or start a fire if not checked by some type short circuit device, which in the case of the air conditioner would be the PTR, or whatever the weakest link may. By the way, I admire your persistence to learn.