How should this thing be wired properly?  Right now to get the A/C working I need to have both red wires connected to R.  But like that the compressor never turns off once the thermostat is reading the correct temp to turn off the A/C. The blower will turn off though.


Right now wires coming into the furnace are/;
red and white from the humidifier connecting to yellow wires of a relay.
red and white from A/C / compressor, red to R, white to C
From the thermostat- white to W, yellow to Y, green to G, and then red to R which runs the blower


I've gone through a few electronic thermostats in the past and have stuck with a regular now.  I ended up messing with wires trying to figure it out before finally determining the t-stat was the problem.  Now I'm not sure exactly what's right.  

The unit is a York Diamond 80.

I don't know, but you could figure out which terminal is putting out 24v to the stat, then use a jumper to find out which terminal does what.

R - 24 volts hot
C - 24 volts neutral
Y - compressor contactor
G - fan relay
W - heat relay

The wires going to the a/c condenser from the furnace should connect to Y and C.  Thermostat and furnace connections should all match up.

Take a picture of the humidifier and the relay.

This right here.

Now for the humidifier, where do the yellow wires go?

Wires from the humidifier



The relay,  Electronic model 50, 24v



The wiring at the humidifier


The only voltage measurement I get is 11.3V between the Y and yellow wire to the t-stat.

To my untrained eyes, looks like you just need to move the red / white wires that go to the compressor, to the Y and C terminals..

Yep, I've done so now and it seems to be working properly.

Thanks

I would replace that air filter too.  

So it had been working fine until today.  Now the AC compressor and fan don't turn on no matter what I do.


If the capacitor tests at 33uF and 5uF for a 35/5 capacitor, should it still work?
The capacitor is too rusted out to see the specs anymore.

If it is a 35 / 5 cap, but testing at 33 / 5, I would replace.  What shape and how many caps in the outside enclosure?

It's a single round one.  I've now replaced that.

Got a better look at the contactor today and saw that the contacts were sooty looking.  I clean the contacts and now it works.

I'll be making another trip to Grainger to replace the contactor too.  At least now it should last through this hot weekend while I'm away.

This. And insulate those flying splices.

Just a tab of tape is adequate.

It beats having them bump each other when you are working.