I found this online and am waiting to hear back from York to see if this is real (If so I am very po'd at the techs who have already replaced one pressure switch, because I shouldn't have to go online to find this out. THEY should stay on top of technical bulletins AND they shouldn't have charged me labor for the install of the last switch). Also i notice that some people online keep telling posters on various boards that it is most likely not the pressure switch, yeah right. SERVICE INFORMATION Unitary Products 5005 York Drive Norman, Oklahoma 73069 1/8778747378 Date: February 5, 2009 YS00209 Revised To: All York Distributors All York Branches All Field Service Supervisors Subject: Pressure Switches PC9, PM9 We have received several product reports regarding pressure switch problems on the 40” modulating 95% furnaces. (Switch P/N S102435308000/ SAP# 157719 upflow models & S102435324000/ SAP# 160209 downflow models) Investigation into these issues and analysis of field returned switches have shown that the fault code 3 is caused by high contact resistance on the electrical contacts within the pressure switch. On each ignition cycle, the modulating furnace control ramps the draft inducer blower up and down and verifies the pressure sensor and switch operation by comparing the switch opening and closing points, as measured by the pressure sensor, to the proper switch set point for that furnace model. If the electrical contacts within the pressure switch body become contaminated with a foreign material, the switch may close mechanically but may not close electrically at the calibrated set point, causing the control to detect a pressure switch that is open when it should be closed. This will result in a 3flash error code, and the furnace control will not continue the ignition sequence. To address this problem, the switch supplier has made a recent change to the switch construction to add an industrial contact lubricant that prevents contamination from adhering to the electrical contact surfaces. Testing has shown that this makes the contacts many times more resistant to contamination by foreign substances. Pressure switches with code dates of 0309 (third week of 2009) will have this new construction. Source 1 should begin to have a limited supply of the new switches available for shipment by February 6 th . The contact contamination problem will not affect any of the NG33 models, even those without the contact lubricant on the pressure switch contacts. The contamination on the contacts is usually silicone carbide, the source of which is the silicone hose connected to the switch. Silicone molecules outgas from the hose and migrate to the switch contacts, eventually affecting the electrical connection. On the NG33 models, which do not have closed burner boxes, there is no silicone hose on the side of the pressure switch in which the contacts are located, and so there is no direct source for silicone contamination. The problem will also not affect previous singlestage or twostage models, since those models do not have pressure sensors that compensate for vent length and firing rate so they always provide a pressure level that insures the contacts are cleaned mechanically on each cycle. This YS letter will provide a replacement pressure switch and one hour labor at the dealers registered DOA labor rate. Due to the nature of this issue, we recommend that the dealers replace the switches now, instead of waiting for them to fail. Make sure you reference the YS letter number when filing claims for this issue. For any units in distributor inventory, this YS letter will allow for replacement of the pressure switch along with a fair and reasonable allowance. Contact Mark Freund at 4054196609 for prior authorization to submit the billing for reworking your inventory. For repair parts in distributor inventory, contact your Source 1 account representative for a Return Authorization of switches with code dates prior to 0309. Mark Freund Robert Cabrera Mark Freund Robert Cabrera Manager, Residential Field Service Director, Indoor Products Engineering

This season my furnace has been acting goofy intermittently. Normal Operation: fans come on, a click or two and everything fires up and works just fine. Sometimes the fans come on, I will hear extra clicking noises, sometimes a lot in rapid succession, and the furnace kicks on and everything is fine. Other times, the clicks happen, furnace starts to kick on, then everything shuts off and after a couple minutes, the cycle starts over and sometimes it fires up and works ok, other times it will go through this cycle several times before the furnace comes on. I recall right at the end of the hot weather (i live in iowa) i heard the clicking noises when i ran the a/c as well. So I am not entirely convinced this is a furnace issue. I think this is a relay problem, the control board has 2 of them on it, but they are soldered to the board. Anybody have any experience with this issue? I have read several posts about the clicking stuff but its always "hear some clicks and nothing happens after that" which is not the case with me. Thanks in advance!!