York RTU stays stuck in heating...

[canmex]

Even when w1 is diconnected, 24v power is at w1 terminal. I replaced board, tested by jumping heat on and off. Problem solved. No, got a call that unit won't come out of heat again..any suggestions??

[PLC]

That should be the only possible reason of having 24 VAC out of the heat output, main board have to be shorted out.

[J.Williams]

possible control wire rubbing a 24v line? its a long shot but worth checking if you have changed the board

[hvacrmedic]

What's the model# of the unit?

[CFESAmasterEGSR]

Heat circuit load too high? (Bad ignition module, partially shorted valve) Excess load welded relay on new board?

That's my two cents. Good luck, definitely odd sounding issue though.

[2sac]

Is it a sunline unit. If it is, I know whats wrong. Are you a tech? You need to check your low voltage circuit. In my experience runaway heat on the sunlines is only caused by 1 thing.

[2sac]

I'll even give you a hint: Something is welded shut. If it's a tan unit it's one thing, and if it's the newer brown units it's another.

[timebuilder]

I'll even give you a hint: Something is welded shut. If it's a tan unit it's one thing, and if it's the newer brown units it's another.

You are SUCH a tease!

[2sac]

You are SUCH a tease!

I am, aren't I

[canmex]

Yea I am a tech. Tan D4CG series

[2sac]

I'm not going to make it easy on you. LOL Look at the heating circuit in your schematic. There is a 3 wire switch whose contacts are welded closed on both sets of contacts. If you follow the schematic, you will see why you have runaway heat. When you replace this you need to order the replacement kit from York, not just the part.

[valdelocc]

Even when w1 is diconnected, 24v power is at w1 terminal. I replaced board, tested by jumping heat on and off. Problem solved. No, got a call that unit won't come out of heat again..any suggestions??

there are 3 ice cube relays, replace the one in the middle.

[2sac]

there are 3 ice cube relays, replace the one in the middle.

Not on the tan units