Generator

[maggie blair]

My generator will allow my air conditioner to start but then the air conditioner shuts down. The generator continues to run but no air. Any ideas? Thanks

[Bill Joyce]

I think the air conditioner might be the problem, since on startup they go through multiple steps and have safety shutoffs at each step.  

[steved44]

You might see if the breaker on the generator is tripped.  Sometimes those breakers get weak and they can trip at too low a voltage.  The generator will continue to run but it's not putting out any electricity.

[Devilishjim]

I'm kinda leaning towards a bad start capicator on AC unit

[I'mdonewiththis forum]

You say the A/C starts but then shuts down. You mean completely or does the fan keep running? What do you do to get the A/C started again? If the compressor starts then the start capacitor is good. I am leaning towards the generator being the culprit, but want more info.

[maggie blair]

 The air-conditioner shuts down completely after a couple of minutes. It runs fine when I'm plugged into electricity. 

[MrSeas]

Did you mention what generator you're using when it happens?

[Yarome]

I'm not sure which generator or what size you have, or the size of your AirCon, but it sounds as if you've got one of three things going on.

1. Your genny is not capable of sustained output sufficient enough to drive your AC. Ie., depending on the brand a 2000watt generator may produce a surge current (for a limited duration) sufficient to kick your AC over, but the operating current may only be 1600watts and drops too quickly for your AC to complete it's startup.

2. You're having a neutral-to-ground issue.

3. Your generator's breaker is tripping from excess power draw.

I agree with Bill. SOUNDS most likely to me like it's your AC failing a check and doing a safety shut-off due to insufficient current. An easy way to tell? Plug in a small 120v device or light, check that your microwave lights are on, etc. If the device/light stays powered when the AC cuts out it's not your genny tripping a breaker and you know it's an AC shut-down.  

If it's your genny throwing a breaker OR an AC safety shut-down there may be a cheap remedy by installing a hard start capacitor to your AC. SPP6 (NOT SPP6E) capacitor.

If it's a neutral-to-ground issue with your generator then you may need to make yourself a plug to address that.

Both cheap and easy potential fixes that might get you up and running.

[Kirk W]

I'm suspicious of the same things previously mentioned. If the generator is still supplying 120v-ac power to things like the microwave or TV but the a/c has shut down completely, that tells me that the cause is not in the generator but in the a/c. If your generator is not capable of supplying enough current without excessive voltage sag, then it could cause the a/c to shut down via one of the safety circuits. We would have to know more about the a/c that you have and also about the generator you are trying to operate it from. What is the "run current" of your a/c and what is the constant load limit of the generator? 

[Devilishjim]

Maggie you have a motorhome with built in generator correct ? If that is so then the generator should be big enough. What kind of motorhome and name on genny and numbers on genny 4000/ 3500 ? the numbers represent the size. Thats what these guys need to know.

[maggie blair]

25 minutes ago, Devilishjim said:

Maggie you have a motorhome with built in generator correct ? If that is so then the generator should be big enough. What kind of motorhome and name on genny and numbers on genny 4000/ 3500 ? the numbers represent the size. Thats what these guys need to know.

It is a 5000 Oman in my RV. My RV is a Class C 32 ft. coachman.

 

 

The air-conditioner shuts down completely after a couple of minutes. It runs fine when I'm plugged into electricity. 

[Kirk W]

1 minute ago, maggie blair said:

It is a 5000 Oman in my RV. My RV is a Class C 32 ft. coachman.

 

Now that makes it really weird. A 5 Kw generator should be capable of supplying a nominal 40 amps, which is well above what your a/c should ever draw. It should even be able to carry the a/c & microwave at the same time and probably a coffee pot as well. 

I would try using the generator to operate some other large loads to see what happens. I would try using the microwave first, then if it works OK, I would add in an electric heater, first on low, then if that holds for 10 minutes, change it up to high(draws about 10a) and perhaps even a second one if you have it. It sounds as though your generator is for some reason sagging in voltage, but it occurs to me that it might also be a frequency problem. If your clocks run too fast, that might be a hint about that issue. Onan generators use frequency/voltage combined to control the load acceptance. It may be that both the voltage and the frequency are off. Have you tested the voltage from the generator with a digital meter? I would check that without the a/c, then turn on the a/c while you monitor the voltage. If it falls more than a volt or two, the frequency is also falling off and may be the issue. 

[Yarome]

Yup.. that certainly changes things. It's still most likely to be a current issue, although you SHOULD have more than enough juice. You want to be sure that, if so equipped, your generators "summer/winter" switch is set properly and your elevation setting is within range of where you currently are. Those can have a similar affect on the issues Kirk mentioned.

Hopefully it's not a mechanical issue with your governor or linkage. The fact that your AC runs perfectly fine on shore power further indicates it's an AC shut-down, although it's sounding more like a generator modulation issue.

[Ronbo]

I doubt if it is the breaker on the genny. He would have known that as he wouLd have to trip it back on. I think Kirk has it with the voltage/frequency. If you have a kill-o-watt plug it in and see what you have. 

[maggie blair]

10 hours ago, Kirk Wood said:

Now that makes it really weird. A 5 Kw generator should be capable of supplying a nominal 40 amps, which is well above what your a/c should ever draw. It should even be able to carry the a/c & microwave at the same time and probably a coffee pot as well. 

I would try using the generator to operate some other large loads to see what happens. I would try using the microwave first, then if it works OK, I would add in an electric heater, first on low, then if that holds for 10 minutes, change it up to high(draws about 10a) and perhaps even a second one if you have it. It sounds as though your generator is for some reason sagging in voltage, but it occurs to me that it might also be a frequency problem. If your clocks run too fast, that might be a hint about that issue. Onan generators use frequency/voltage combined to control the load acceptance. It may be that both the voltage and the frequency are off. Have you tested the voltage from the generator with a digital meter? I would check that without the a/c, then turn on the a/c while you monitor the voltage. If it falls more than a volt or two, the frequency is also falling off and may be the issue. 

Thanks so much Kirk. I will check into this today. I will have someone look at it and get this resolved. I am on electricity most of the time so it hasn't been a big issue. Thanks again. 

[DJohns]

Does the AC work when plugged into shore power?

[Kirk W]

1 hour ago, Dan Johnson said:

Does the AC work when plugged into shore power?

Answer ....

12 hours ago, maggie blair said:

The air-conditioner shuts down completely after a couple of minutes. It runs fine when I'm plugged into electricity. 

 

 

[maggie blair]

7 hours ago, Dan Johnson said:

Does the AC work when plugged into shore power?

Yes

[Devilishjim]

Maggie are there possibly reset buttons on that generator ? Something tells me you aren't getting full voltage, but thinking about all the cold weather maybe one of those hand flippin fans would work

[maggie blair]

On 4/6/2017 at 9:19 PM, Kirk Wood said:

Now that makes it really weird. A 5 Kw generator should be capable of supplying a nominal 40 amps, which is well above what your a/c should ever draw. It should even be able to carry the a/c & microwave at the same time and probably a coffee pot as well. 

I would try using the generator to operate some other large loads to see what happens. I would try using the microwave first, then if it works OK, I would add in an electric heater, first on low, then if that holds for 10 minutes, change it up to high(draws about 10a) and perhaps even a second one if you have it. It sounds as though your generator is for some reason sagging in voltage, but it occurs to me that it might also be a frequency problem. If your clocks run too fast, that might be a hint about that issue. Onan generators use frequency/voltage combined to control the load acceptance. It may be that both the voltage and the frequency are off. Have you tested the voltage from the generator with a digital meter? I would check that without the a/c, then turn on the a/c while you monitor the voltage. If it falls more than a volt or two, the frequency is also falling off and may be the issue. 

Thanks so much. I got that fixed but now have an issue with the engine.  I climbed my first hill here in North Carolina yesterday and when I push the pedal all the way to the floor it makes a grinding noise. When I let off of the pedal the noise stops but I ended up going 40 mph. I am learning so much on this site from you and I appreciate all of your input. Thanks again. 

[Kirk W]

40 minutes ago, maggie blair said:

 I climbed my first hill here in North Carolina yesterday and when I push the pedal all the way to the floor it makes a grinding noise. When I let off of the pedal the noise stops but I ended up going 40 mph.

 

You are asking something well beyond my knowledge base but I would get a good mechanic to ride with you as soon as feasible. That sounds like a serious mechanical problem. 

[maggie blair]

Thanks Kirk. Taking your advice and called Ford in the morning. 

[I'mdonewiththis forum]

6 hours ago, maggie blair said:

  I climbed my first hill here in North Carolina yesterday and when I push the pedal all the way to the floor it makes a grinding noise. When I let off of the pedal the noise stops but I ended up going 40 mph. I am learning so much on this site from you and I appreciate all of your input. Thanks again. 

Maybe the noise is the sound of your toe nails hitting the fan?

[mscans]

It is possible that the frequency output of the generator (60 Hz,) is out of line.  Many items will run fine with incorrect frequency but the A/C may be pulling a high load due to the low frequency, most other appliances don't care.  A Kill-O-Watt meter can check the frequency else you have to see an electrical tech.

Good luck, let us know what you find.

[maggie blair]

Thanks so much for all the information. Another RV friend figured it out so everything is working good now. Thanks again.