[PatFlemming]

I've tried booting up my AC unit for the first time this spring and it's not turning on.

The furnace fan turns on but the AC doesnt budge. I checked the obvious things and all looks good - thermostat appears to be wired correctly, the drain line is not clogged, fan isnt seized, breaker isn't tripped.

I used a voltage tester and there doesnt seem to be any power feeding the unit. However, the thermostat wire seems to set off my tester so it has power running through it.

Any idea on what could be the problem??

 

[roughneck]

So you have a call for cooling, the contactor is pulled in but you don’t have line voltage feeding the unit?
The condenser will be off a separate power feed then the furnace. It’ll be a double pole breaker.

 

[PatFlemming]

So you have a call for cooling, the contactor is pulled in but you don’t have line voltage feeding the unit?
The condenser will be off a separate power feed then the furnace. It’ll be a double pole breaker.

I have a double pole breaker labelled "AC" which I turn off in the fall. I turned it back on this spring like I always do. I tired resetting it a few times also.

 

[roughneck]

Do you have power at the disconnect switch for the condenser?
Is the disconnect fused or non-fused?
You’ll have to backtrack from the condenser using your meter.

 

[PatFlemming]

So, i ran a few more tests. I had someone call for AC at the thermostat while I was at the unit with the panel removed. I heard a click and then a humming noise but the AC didnt turn on. Also, the capcitor looks corroded. not sure if this has anuthing to do with it. Stangely, still no reading from my voltage tester on the 240V.

 

[roughneck]

As I said before, your furnace has power but the condenser circuit doesn’t. Capacitor has nothing to do with the issue. Your contactor is working normally as it gets control voltage from a separate source.
You need to find where your losing voltage. Disconnect, fuses, breaker, wiring.

 

[dj3]

If you have a disconnect near the condenser, replace the fuses (with the same exact kind).
Then make sure the bar is positioned the right way.

 

[roughneck]

If you have a disconnect near the condenser, replace the fuses (with the same exact kind).
Then make sure the bar is positioned the right way.

No reason to replace the fuses, when they can be easily tested. If the OP has them in the first place.
And if the OP were to replace them and they blew right away, he’d be back to square 1 with no diagnosis.

 

[dj3]

You're right.