One or both capacitors bad?

[Damdifino]

My Coleman Mach 15K A/C makes a groaning noise but won't start up. Same thing for the fan by itself. There are two capacitors on the roof, one for each, plus a hard start capacitor on the compressor side. I removed all three and tested them with an analog multimeter; I do get some needle movement but not all the way to zero. I checked and I do have 120V to the trailer. What are the chances more than one capacitor could fail at the same time?

Oh, and could these symptoms be the result of inadvertently short-cycling the A/C?

[j-d]

If you used a sensitive Analog VOM... By that I mean one with a goodly Ohms per Volt, like 20,000... it should "Kick" and drop to Zero on a High Ohms scale. If you take the leads off and put them back the same way, meter should stay Zero. If you reverse the leads it should Kick higher than it did at first.
That said, there are inexpensive DVOMs (Digital VOM) with Capacitance capability. A BFF gave me a Fluke that does it but I know Harbor Freight has one under $30 that'll do it and imagine places like Lowe's HomeDepot WallyWorld might too. I consider a DVOM and Clamp-On AC Ammeter to be essential to the Repair-it-Yourself RVer. With those, you can do lots of troubleshooting up to and including your A/C. My daughter had a Harbor Freight clamp-on AC meter when we came to a warm refrigerator/freezer that was groaning then clicking off. When I oculd see the compressor was drawing locked rotor amps, we dug deeper and found the start kit had failed. Replaced with a SUPCO kit and it's been running several years. Appliance parts man told me that aging compressors take more to start, and that may take out the start device.
If it's 15K and Coleman, that's what we have, and there are three components: Compressor Cap, Fan Cap, and Compressor Start. In my case it's a Start RELAY. It could be a PTC device. That's what failed in my daughter's fridge. A SUPCO start kit like SPP6 replaces PTC. SUPCO SPP6E replaces Relay. Relay and 6E are the premium choices. Take your Coleman Model Number If you used a sensitive Analog VOM... By that I mean one with a goodly Ohms per Volt, like 20,000... it should "Kick" and drop to Zero on a High Ohms scale. If you take the leads off and put them back the same way, meter should stay Zero. If you reverse the leads it should Kick higher than it did at first.
That said, there are inexpensive DVOMs (Digital VOM) with Capacitance capability. A BFF gave me a Fluke that does it but I know Harbor Freight has one under $30 that'll do it and imagine places like Lowe's HomeDepot WallyWorld might too. I consider a DVOM and Clamp-On AC Ammeter to be essential to the Repair-it-Yourself RVer. With those, you can do lots of troubleshooting up to and including your A/C. My daughter had a Harbor Freight clamp-on AC meter when we came to a warm refrigerator/freezer that was groaning then clicking off. When I oculd see the compressor was drawing locked rotor amps, we dug deeper and found the start kit had failed. Replaced with a SUPCO kit and it's been running several years. Appliance parts man told me that aging compressors take more to start, and that may take out the start device.
If it's 15K and Coleman, that's what we have, and there are three components: Compressor Cap, Fan Cap, and Compressor Start. In my case it's a Start RELAY. It could be a PTC device. That's what failed in my daughter's fridge. A SUPCO start kit like SPP6 replaces PTC. SUPCO SPP6E replaces Relay. Relay and 6E are the premium choices. Take your Coleman Model Number If you used a sensitive Analog VOM... By that I mean one with a goodly Ohms per Volt, like 20,000... it should "Kick" and drop to Zero on a High Ohms scale. If you take the leads off and put them back the same way, meter should stay Zero. If you reverse the leads it should Kick higher than it did at first.
That said, there are inexpensive DVOMs (Digital VOM) with Capacitance capability. A BFF gave me a Fluke that does it but I know Harbor Freight has one under $30 that'll do it and imagine places like Lowe's HomeDepot WallyWorld might too. I consider a DVOM and Clamp-On AC Ammeter to be essential to the Repair-it-Yourself RVer. With those, you can do lots of troubleshooting up to and including your A/C. My daughter had a Harbor Freight clamp-on AC meter when we came to a warm refrigerator/freezer that was groaning then clicking off. When I oculd see the compressor was drawing locked rotor amps, we dug deeper and found the start kit had failed. Replaced with a SUPCO kit and it's been running several years. Appliance parts man told me that aging compressors take more to start, and that may take out the start device.
If it's 15K and Coleman, that's what we have, and there are three components: Compressor Cap, Fan Cap, and Compressor Start. In my case it's a Start RELAY. It could be a PTC device. That's what failed in my daughter's fridge. A SUPCO start kit like SPP6 replaces PTC. SUPCO SPP6E replaces Relay. Relay and 6E are the premium choices. Take your Coleman Model Number to RVComfort here and it should tell you what the three parts are, including value for the Capacitors. You can get either a combo cap or two caps and connect them to get a common.

[Bill_T]

If it is a dual capacitor yes it could affect both componets. Not likely both caps went out at the same time, but never say never. I would be inclined to check for low voltage at the ac unit.

[rkentzel]

Yes you can by visible looking at the condition and or by using a meter, or a capacitance meter.

[YC_1]

Could be you just need to spin the squirrel cage by hand to loosten up the grease. You really can't thoroughly test a capacitor with an ohmeter. Replacement it the best option.