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Tim H.
Tim H., HVAC Professional
Category: HVAC
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Experience:  Experienced in all aspects of HVAC, both residential and commercial.
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the transformer has 115volt input and it does has 24volt output

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the transformer has 115volt input and it does has 24volt output to the intergrated furnace control. the blue and red wire going from the intergrated furnace control to the pressure switch located on the gas valve is not receiving voltage from the intergrated furnace control at all while I am holding the access panel switch in manually. I checked this with a multimeter. the actual transformer input voltage is 120V and the output is 27V. In short the pressure switch is not allowing gas flow for ignition of the furnace. Please advise.
Russ here.. Trane Service Manager. How far does it get in sequence of operation. Thermostat calls for heat,small fan starts,pressure switch closes,igniter glows,gas valve opens,ignition,flame sensor proves flame. Russ
Customer: replied 3 years ago.


Hello Russ,


Thermostat calls, small fan starts, igniter glows. As far as I can tell the pressure switch which is located on top of the gas valve is not getting any power through the blue and red wire coming from the intergrated furnace control and therefore the gas valve is not opening and no ignition after that. I held my multimeter on the blue and red wire through the whole sequence and the voltage stayed at zero volts.


John

Customer: replied 3 years ago.
Relist: Other.
no answer and tired of waiting.
Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Please provide all information I request as it makes it more difficult to troubleshoot something when I'm not there onsite. Essentially, you become my eyes and ears. Thanks for the opportunity to help. At the end of our dialog, you will have a chance to rate my service, but please wait until we are finished and you're satisfied you have all the information you need.
Looks like Russ is offline. When you say you are getting "0" volts, do you mean at the gas valve?
Customer: replied 3 years ago.

yes sir

The valve should receive 24 volts AC (not DC) shortly after the ignitor begins to glow. If it is not receiving voltage, it would tend to indicate a bad board if the call for heat is still there.
Customer: replied 3 years ago.


That's what I was thinking as well but wanted an expert to agree. I was set up for AC voltage in all my measurements. Would you suggest I get a Hvac technician to change it or do you think it is easy enough for a do it yourselfer?

If you are comfortable working with gas, they are not that complicated to change out. Wiring is fairly simple. It's just that some people get "spooked" by working with gas.
Tim H., HVAC Professional
Category: HVAC
Satisfied Customers: 3971
Experience: Experienced in all aspects of HVAC, both residential and commercial.
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