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

[valdelocc]

Not on the tan units

missed the "tan" part, if my memory doesn't fail me, in the older yorks w1 powers the inducer and after the centrifugal swt closes, the 24v travels through the safties and lands on the Johnson, right? I dont do RTu's as much anymore.

[2sac]

The tan units have (2) 24v supplies to the JC ignition control The control needs to see voltage at both before firing off

[hvac69]

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.

Seen this many times

[canmex]

Not on the tan units

Looks that limit switch was the deal. Thanks for all the insite. Never had that one before! Thanks again!And yea it's an assembley you get not just the switch.

[canmex]

Yea. After tracing it all out,that limit switch was the issue. And Yea you get the assembley not just the switch. Thanks for all the input and advise. Never seen that one before...

[deux]

I had one run away over xmass. The customer had a HUGE fish tank. All you could smell was fish. It was so hot
in the bay it melted his hard drives, and cooked his fish. Just some bones bobbing around in the tank. It was the
3 wire limit issue.