trane

Paul S_3

I went to a no heat call on a 10 ton(gas) TRANE 2 stage packaged unit(model#YHC120e).i think i found a faulty 2 stage 24v gas valve. I would like some insight with this diagnosis. This unit has (1) circuit board which is for heat.....the inducer motor will start @ high stage then switch to low (1st) stage  ,it will make the pressure switch and then the spark ignitor will start sparking....it will attempt to energize the gas valve(low or 1st stage) for a split second then the board will de-energize(sparking from board is for a split second too)...it seems like the gas valve's coil is shorted or something wrong with it and the board de-energizes asap....i disconnected the wires to the 1st stage gas valve coil and put my meter to it ....the sequence of operation is the same except that the heating board is energizes the wires to the GV continuously (spark ignitor stays on longer too)until it locks out.......has anyone experienced these TRANE circuit boards operating similar???? it seems like the board recognizes a problem with the coil on the GV....

unclejohn

Sounds like

You got it. You might just connect a 24v relay where the gas valve was to see if its just not a bad wire connection inside a harness. If it takes the load of the relay and keeps sparking like before when you just disconnect the wires I'd go for the valve replacement