Aprilaire 600A won't turn on

**mortal798** · 10-28-2011, 01:09 PM

Hi everybody,

I have an Aprilaire 600A, and just like the title says - it won't turn on. I have 24vAC at the 'R' and 'C' terminals in the controller. The water solenoid is hooked up to 'H' terminals. The outdoor temp sensor is hooked up to 'ODT.' And the unit is set up to use the call for heat from the t-stat to detect blower operation, so 'W/G' on the Aprilaire controller is hooked up to 'W' on the furnace board and 'Cf' on the controller is hooked up to Common on the furnace.

Does it sound like my connections are correct? It won't even light up in 'Test/Reset' mode. Any ideas? Thanks in advance!

**mortal798** · 10-28-2011, 03:00 PM

Oh yeah, just another piece of info - it doesn't work with the manual resistor either...

**DonL** · 10-28-2011, 04:18 PM

Is that a new install ?

Did it ever work ?

**jadnashua** · 10-28-2011, 04:41 PM

The solonoids don't last forever...you can just replace that, if it's the problem. If it has 24vac across the input to the solonoid, but it hasn't turned on, it's probably that.

**mortal798** · 10-29-2011, 07:17 AM

Originally Posted by DonL

Is that a new install ?

Did it ever work ?

It used to work, I turned it off for the summer. Then I removed the old furnace and replaced it. Once I reconnected the 600A, it wouldn't turn on. I have 24vAC at the controller, but the display doesn't light up - and it won't even go into test mode. I think I may have a bad controller.

The furnace works like a million bucks, just that d#$* humidifier won't come on.

**DonL** · 10-29-2011, 08:57 AM

Originally Posted by mortal798

Hi everybody,

I have an Aprilaire 600A, and just like the title says - it won't turn on. I have 24vAC at the 'R' and 'C' terminals in the controller. The water solenoid is hooked up to 'H' terminals. The outdoor temp sensor is hooked up to 'ODT.' And the unit is set up to use the call for heat from the t-stat to detect blower operation, so 'W/G' on the Aprilaire controller is hooked up to 'W' on the furnace board and 'Cf' on the controller is hooked up to Common on the furnace.

Does it sound like my connections are correct? It won't even light up in 'Test/Reset' mode. Any ideas? Thanks in advance!

The 2 H output terminals should have the 24VAC always-on transformer output winding is series with the solenoid,
connected to them.

Measuring from terminal H - H You should see 24VAC when the unit is not calling for humidity.

**mortal798** · 10-29-2011, 07:22 PM

Originally Posted by DonL

The 2 H output terminals should have the 24VAC always-on transformer output winding is series with the solenoid,
connected to them.

Measuring from terminal H - H You should see 24VAC when the unit is not calling for humidity.

Yes, and when the solenoid comes on all the voltage should drop. The solenoid coming on isn't the problem (well, it may be a problem later...), the controller doesn't come on to tell the solenoid to come on. The controller doesn't even light up in test mode.