York Rooftop Unit/Johnson Pilot Ignitor Issue

Midwestguy954

I'm troubleshooting a York rooftop unit that has a G775 RJD-12 Int. Pilot ignitor on it. First of all right off I seen the power ventor was bad so replaced it. Expecting it to be fine then but not. Always during start up the ignitor sparks. So I checked the 24v to pilot gas valve and I had it. So I figured gas valve problem. But then a few minutes later I lost the 24v to the gas valve during ignition. Never have I had a pilot flame. It got dark and I quit there. I need to know how this control sequences or possibly someone can pass on to me some ideas. Thanks.

greghvacguy

If you where getting 24 volts to gas valve was it sending gas to cross lighter.(you would smell it at the inducer)make sure cross lighter is open not clogged with spider. make sure spaerker is sparking on the cross lighter and flame sensor is clean..

MechAcc

Yep York loves to use that perforated tube for their lighter bar. You will not be able to blow spider webs out with compressed air. Run a wire down the tube several times that will break the web free.

If the venter wheel was badly rusted I would also look at the heat exchanger for splits on the tubes. The excess air can cause the wheel to rust.

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snapperhead

that Induced Draft motor has to prove the pressure switch for the 24Vs to the gas valve......the air from the ID might be bouncing the 24Vs???jump the switch to verify it is the switch "just on a test run" to get the main burner to run consistantly.

Miller257

Check the pressure switch, you might be loosing it there. Then check the heat exchanger. Depending on the age of the unit the heat exchanges like to split on the seams. I've replaced 3-4 already and have another 20 out there with that same heat exchange. The best part is York made it nice and difficult to change those things out. Good Luck!