roof air question

The sample time of a DVM is longer than the action of the capacitor charging to the battery in the ohm meter, so you probably won't see anything. However, if you see any resistance other than infinity after leaving the test leads on the capacitor for a few seconds, the capacitor is bad. The end of the capacitor the terminals come out of should be flat. The capacitor is probably bad if swollen.

i have a digital meter not a analog can i use it the same as if i were testing a heating element

its has no auto setting it the one on the ceiling that you turn by hand its goes like this low fan ,high fan,low air, high air. that how it operates on each click of the setting on the switch. on low fan high fan its blows good then when i click it over to low air or high air it sound like it trying to kick the fan on most time it will kick in start blowing and working fine but most time it takes it a few seconds to get the fan blowing hard .

Check it with an analog ohm meter on about a 10K range. When connecting to a disconnected capacitor, each section should briefly pulse the meter and then return to infinity. Then try it again by reversing the meter leads. It should deflect again even more than before and again return to infinity. Any other result is a bad capacitor.

Have you tried setting the fan on auto and then turning on the air. The unit should wait up to three minutes to "prepare" and then come on.

its tripping the air cond breaker sometime if it does not kick in and start blowing it will kick the breaker so this might be a compressor capacitor is what one person said how would i check these capacitors to see if their good i know its has two one for the motor and one for the compressor.i know they sometime swell up or leak . but how do i check it with volt meter.the motor run fine on high amd low on fan . but like i said when i switch it too low or high air it may take it a min to start blowing if it dont kick breaker first.

Carefully check the wiring connectors at the unit also inspect the start capacitors for the compressor

Which breaker is tripped?
You're assuming there is a problem with the fan but the A/C compressor draws ten times what the fan does.

I would check the 120 volt connections in the 120 volt power distribution panel.
Make sure you check the neutrals.
Disconnect power to the rig!