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A/C Compressor Fails To Run


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#1 Doug Simpson

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Posted 27 July 2012 - 07:12 AM

My bedroom A/C unit is a Coleman model 9214-876, a 15,000 BTU non-ducted model. When I attempt to start it, the blower starts OK but I can hear the compressor attempt to start and, after about 2 or 3 seconds, the compressor shuts off. After a delay of 5 to 10 seconds, the compressor attempts to start again then shuts off after 2 or 3 seconds. I have 50 amp service and two A/C units and both A/C units have run fine for the first 2 days at this campground so I have no reason to believe that there is a problem with shore power which was 117 volts when I attempted to start the A/C unit. I have a Kill-O-Watt meter plugged into a nearby outlet and I observed the voltage as I attempted to start the A/C. The puzzling thing is the voltage rises to 123 volts when the compressor attempts to start then returns to 117 volts. Normally, the voltage will drop a few volts when an A/C unit starts.

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#2 Mr. Dave

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Posted 27 July 2012 - 07:31 AM

Sounds similar to mine when the start capacitor failed. Once replaced it ran like new again. Doesn't sound like your voltage is too low at the park. 117 is right up there. Hope this is of some help.

2006 Coachmen Aurora 36ft. Class A motor home. 2009 Honda CRV toad. "Snowbirds" apprx. 6 mos. each year. Travelling to the SW each winter than returning to Wi. each summer. Retired and enjoying our travels along with Buddy the cat.


#3 Ozz

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Posted 27 July 2012 - 07:36 AM

Hi Doug,
You could have a few things that are causing this. First, and most common is a bad capacitor. Many have a 'split' or 'Dual' capacitor, they have the fan motor and compressor capacitor all in one. The compressor half of the capacitor may be bad. Another possibility is the compressor is tight and just won't start. The compressor has an electric motor and refrigerant compressor combined. You could have bad components as well, bad relay, and so on.
I suggest first getting the dual capacitor and changing it, you can buy a start capacitor and add it at the same time, it will come with directions, just mark the fan wire, compressor wire and common wire when you change it. Easy-peasy.
Most RV places will have the parts. The dual cap will be something like a 45-5-440v, it will have a tag on it.
You can get it at a refrigeration, or HVAC supply shop as well. Read the tag, then go get the part. The hard-start cap kit will have the BTU on the package.

Good luck. Ozz
5 years of Pipefitter apprentice, Machinists school, and 4 years as a machinist and machine repairs. 2 years repairing Nuke and convential submarines. One year running my own machine shop,
3 years in refrigeration and electrical schooling, 35 years as a HVAC, refrigeration and electrical serviceman and my own businesses as a contractor.

#4 Kirk

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Posted 27 July 2012 - 08:34 AM

Ozz has covered this one well. You may want to try the start capacitor simply because they are easy to do and not expensive. It is probably beyond the ability of most RV owners to go much farther in trouble shooting since the a/c is not easy to work on. ;)

Good travelin !...............Kirk
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#5 Doug Simpson

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Posted 28 July 2012 - 05:01 PM

Thanks for the help, guys, especially the pro, Ozz. As soon as I get out of this 90+ degree weather, I climbing up on the roof and removing the A/C cover and see if I can identify and remove the start capacitor. I went to the website for AIRXCEL RV Products Division, the manufacturer of the A/C unit. My model is no longer in production so I looked at the documentation for the replacement model. The A/C Wiring Diagram shows a fan capacitor, start capacitor, and run capacitor. The Parts List, which includes an exploded diagram, shows a fan capacitor, run capacitor, start device package. This start device package is shown as two pieces on the exploded diagram. On the AC Wiring Diagram, a resistive element is attached to the top of the start capacitor and labelled "PTCR." What do you suppose this is all about? I sent an email to AIRXCEL tech support for some help finding documentation for my model. I hope they respond by early next week.

Edited by Doug Simpson, 14 October 2012 - 11:25 AM.

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#6 Ozz

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Posted 28 July 2012 - 05:09 PM

It is a bleed Resistor.... Change all 3 caps, same age on them, so it just makes good sense.

Edited by Ozz, 28 July 2012 - 05:10 PM.

5 years of Pipefitter apprentice, Machinists school, and 4 years as a machinist and machine repairs. 2 years repairing Nuke and convential submarines. One year running my own machine shop,
3 years in refrigeration and electrical schooling, 35 years as a HVAC, refrigeration and electrical serviceman and my own businesses as a contractor.

#7 Big Greg

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Posted 28 July 2012 - 07:55 PM

This is a common failure, I had it 2 years ago. You have a bad start cap & PTCR. After you remove the AC cover remove a sheet metal cover over the electrical components and you will probably see the cap blackened and the PTCR burnt. Mine was quite visable. Sometime when they fail you can smell it inside your RV. Most all RV shops should have a repair kit, I have also found them online. I was able to find the AC manual and parts list on the manufacturers website. A new start cap & PTCR were about $35. Greg

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#8 Big Greg

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Posted 28 July 2012 - 07:56 PM

Duplicate, bad internet connection.

Edited by Big Greg, 28 July 2012 - 08:20 PM.

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#9 Big Greg

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Posted 28 July 2012 - 07:56 PM

Duplicate, bad internet connection. Greg

Edited by Big Greg, 28 July 2012 - 08:15 PM.

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#10 Doug Simpson

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Posted 03 August 2012 - 09:26 AM

I removed the A/C cover and found and removed the start capacitor. Piece of cake. I also found and removed a large bird's nest next to the compressor. The capacitor did not have any obvious signs of damage but a meter showed it to be shorted. I ordered a new one from Amazon. Should be here Monday. I'll let you know if this solves the problem.

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#11 Ozz

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Posted 03 August 2012 - 09:43 AM

I removed the A/C cover and found and removed the start capacitor. Piece of cake. I also found and removed a large bird's nest next to the compressor. The capacitor did not have any obvious signs of damage but a meter showed it to be shorted. I ordered a new one from Amazon. Should be here Monday. I'll let you know if this solves the problem.


Hope that is the problem, good work. Darned birds.. :)
5 years of Pipefitter apprentice, Machinists school, and 4 years as a machinist and machine repairs. 2 years repairing Nuke and convential submarines. One year running my own machine shop,
3 years in refrigeration and electrical schooling, 35 years as a HVAC, refrigeration and electrical serviceman and my own businesses as a contractor.

#12 Kirk

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Posted 03 August 2012 - 12:13 PM

The capacitor did not have any obvious signs of damage but a meter showed it to be shorted.


A capacitor will read a short at first and eventually if you keep the leads on it long enough, it will begin to read a resistance as it charges up. Your meter when measuring ohms supplies a very small current and the start cap is a large capacitor so it would take a very long time to charge it with the meter. Resistance readings really don't tell us much with larger capacitors. The small ones found in common circuits can be checked that way, as they pass current in one direction until they are fully charged, the stop and measure a very high resistance. But you then need to discharge it before you measure in the other direction, or you will damage the ohm meter. With the leads reversed you would get pretty much the same readings as before until the cap charges in the other direction.

We will hope that this is the problem, but your meter reading was very much normal for a discharged capacitor, but that don't prove it to be good or bad. ;)

Good travelin !...............Kirk
Author & Escapee's Magazine contributor
Full-time 11+ years...... Now seasonal travelers again.
Kirk & Pam's Great RV Adventure
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#13 Doug Simpson

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Posted 06 August 2012 - 08:40 AM

I ordered the Supco SPP6E replacement capacitor from Amazon - $21.36 plus 10.98 for 2 day shipping. Less than a local RV dealer wanted for an OEM cap with 1 week shipping. I installed it in less than 15 minutes and the A/C is blowing cold air again. Thanks for all the help, guys.

Edited by Doug Simpson, 06 August 2012 - 08:41 AM.

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#14 azman1968

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Posted 06 August 2012 - 08:50 AM

My bedroom A/C unit is a Coleman model 9214-876, a 15,000 BTU non-ducted model. When I attempt to start it, the blower starts OK but I can hear the compressor attempt to start and, after about 2 or 3 seconds, the compressor shuts off. After a delay of 5 to 10 seconds, the compressor attempts to start again then shuts off after 2 or 3 seconds. I have 50 amp service and two A/C units and both A/C units have run fine for the first 2 days at this campground so I have no reason to believe that there is a problem with shore power which was 117 volts when I attempted to start the A/C unit. I have a Kill-O-Watt meter plugged into a nearby outlet and I observed the voltage as I attempted to start the A/C. The puzzling thing is the voltage rises to 123 volts when the compressor attempts to start then returns to 117 volts. Normally, the voltage will drop a few volts when an A/C unit starts.



#15 azman1968

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Posted 06 August 2012 - 08:51 AM

You unit sounds like the start cpacitor is bad try that 9 times out of 10 it works

#16 Ozz

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Posted 06 August 2012 - 09:31 AM

I ordered the Supco SPP6E replacement capacitor from Amazon - $21.36 plus 10.98 for 2 day shipping. Less than a local RV dealer wanted for an OEM cap with 1 week shipping. I installed it in less than 15 minutes and the A/C is blowing cold air again. Thanks for all the help, guys.


Super Doug! Glad you whipped it into shape :)
I have an extra service truck if you run out of 'walking around money..'
5 years of Pipefitter apprentice, Machinists school, and 4 years as a machinist and machine repairs. 2 years repairing Nuke and convential submarines. One year running my own machine shop,
3 years in refrigeration and electrical schooling, 35 years as a HVAC, refrigeration and electrical serviceman and my own businesses as a contractor.