Start capasiter

Replace it. If it's bulging or leaking replace it. There are testers but replace it.

Duplicate

Place a voltmeter ahead of a starting capacitor. If voltage drop when the motor tries to start but the motor hums the problem MAY BE the starting capacitor. An overnight leakdown test is another crude but better than nothing test.

There is a replacement interval for them on home AC systems (forget what it is now). I replaced the cap on our resi AC because the motor would make a loud "clang" when it started. The cap looked fine but the interweb expoained the issue.

A hard start capacitor is easy to replace the regular start cap. I changed quite a few on RV's when I had the Appliance /ac shop

Slownsy wrote:
How do on test if a start capasiter is working thanks.
Frank.

If you're going to go to all the trouble to pull the covers after getting on the roof just change it after you open it up.. you probably mean the " run " capacitor as very few rv units have a start cap/potential relay from the mfg. best way for either is an actual capacitance meter but if you have an older analog volt meter put a lead on each terminal & meter will swing if close to good. Visual check on lots of them is all that's needed, bulging top, leaking, bad terminal etc.
Why do you suspect cap ?

Ok thanks all for the suggestions.
Frank.