AC roof unit doesn't work

I think you're right. Lots of times a bad cap will show as bulging or burned. I've replaced several that were bulged and it fixed my problems which were the same as yours.

If you have a diagram, it should be the compressor start cap. They are sometimes
plastic cased so you wouldn't see a bulge. Also if you have
2 of the same roof units, you can switch the caps. form your other
unit to determine which cap. is faulty.
Brian

I guess you know the caps are charged so be careful and discharge those suckers before you handle them.

how do you discharge it other than having no electricity running through the system?

bidhounds wrote:
how do you discharge it other than having no electricity running through the system?

Disconnect it from the circuit and then jump the two terminals with a screwdriver shaft that has a good insulated handle....

Just a note on safety: The caps will remain charged even though there is no electricity running through the system. It will eventually bleed off but do what 10forty2 said before messing with them.

bidhounds wrote:
HI All,

2007 Itasca Sunova 35j

I have 2 AC roof units. Back one works fine. Front one will blow air on hi and low when I turn it on. When I turn it to auto and then cool, the thermostat clicks and the unit buzzes like it's trying to get going but does nothing. I opened it up and fan turns fine manually. I try to help it get going while it's buzzing, but nothing. There are 3 capacitors. I am thinking the problem is one of those. Thoughts?

Change them out with a hard start kit, as it's sometimes called and the compressors start capacitor is the most likely culprit. What ever you have left over, with buying them all, keep for a spare.
I changed one out on the road last year and found it at a trailer sales dealer, but if no hurry, Amazon should have what you need. Again, no problem if it doesn't work, as it's nice having a spare on board and it's not like they're overly expensive.

Warning on caps.. The best way to discharge is to load 'em down.. But electrolytic caps can ... "recover" if you use the screwdriver short method.
Rare. but it happens

On one Internet TV show I watch they have invented the "Chip Stick" for discharging power supply caps...

Basically a small resistor (Large capacity small resistance) with leads on a paint stirrer so you never touch a hot wire.

You'd need two. one for each terminal