Trane XL 90 Will not fire. Cold in Michigan PLEASE HELP

[pcSLIDER]

I have a Trane XL 90 Model number TDC080B942A1 80000 btu natural gas. Quick explanation of problem when the thermostat calls for heat the inducer motor comes on and that is where it end inducer motor continues to run with no further action. Replaced the HSI last year. Normal procedure would be thermostat call for heat then inducer motor starts HSI begin heating snap of gas valve burner ignition blower motor and warm house. Now Only inducer motor not snap of gas valve not HSI heating no Gas smell no flame. Thank you for any assistance.

[SeattlePioneer]

There are probably some diagnostic lights visible through the fan compartment viewing port. Please report the light cobination and the description of the diagnotic code probably given on the cover of the fan compartment od in the burner compartment.

You can also use an AC voltmeter to check and see if the pressure switch is closing.

[pcSLIDER]

Originally Posted by SeattlePioneer

There are probably some diagnostic lights visible through the fan compartment viewing port. Please report the light cobination and the description of the diagnotic code probably given on the cover of the fan compartment od in the burner compartment.

You can also use an AC voltmeter to check and see if the pressure switch is closing.

Thanks for the response their is only one diagnostic light and it is out says if on replace module if blinking refer to manual. The pressure switch I belive is working I can seen and hear it work. What would be the next step to check. Thanks again

[SeattlePioneer]

Youn still need to measure the voltage on both sides of the pressure switch and find out if it's closing. Listening to it doesn't cut it as a diagnostic method.

Let's put it this way --- if the pressure switch is closing as you suggest, you may well need a new corcuit board for $200. or so. Or you might have a pressure switch that's broken and not closing the electrical switch --- cost $60 for a new pressure switch.

Of course, you only get to buy the $60 pressure switch AFTER you've already bought and installed the new circuit board --- so total cost $260 or so so far.

I prefer measiring and testing to guessing and supposing, but to each their own.

[ecman51`]

Originally Posted by pcSLIDER

Replaced the HSI last year.

As suggested - always test; do not presume. It could have been dropped, mishandled, defect, etc.

I had an HSI go out on me about 1 year ago, where **it** lasted 364 days. No joke. I made the one year warranty deadline.

[pcSLIDER]

tested pressure switch it is good I belive the HSI control module maybe bad model #50E47-60 White Rodgers. The hsi does not heat up their is no light on Tr to TH has 24v , Ign 0v L 120 v any thoughts everything I have read tells me it is bad.

[SeattlePioneer]

http://www.white-rodgers.com/wrdhom/.../0037-6426.pdf


This isn't the exact model you have, but it may be worthwhile reviewing the sequence of operation described on pages six and seven to see if you have similar diagnostic codes and to follow the troubleshooting procedure described.

Based on what you've described though, I'd replace the module.

[pcSLIDER]

Thank you seattle for all your assistance about as sure as I can be my only concearn now is finding the replacement at a good price the the replacement is the -843 that you link to the local HVAC supply company sells for $76.50 but they will not sell to me the local heating company for our small town say $122.75 Luckily I have been heating with a small zero clearance fireplace and using the fan only option on the furnace to circulate heat. Thanks again.

[pcSLIDER]

The problem has been resolved it was the HSI control module replaced it andworking great. Thanks for all the help recieved.