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jonwilliam · Feb 18, 2009, 06:30 PM

Hi Gents,

Upon checking out the pressure switches on this TRANE furnace , found out that PO1 is not completely open that means shows few ohms and not zero out whilst the PO2 is completely zero out . Any specific reason for that or the switch is kind of over edge . Your comments will be appreciated

mygirlsdad77 · Feb 18, 2009, 06:43 PM

Usually a pressure switch is open or closed. Ohms usually don't have a factor in pressure switches, however, it is possible. Hope one of the other guys will give you some answers.

I would like to know why you are ohming switch. Can you let me know what the furnace is doing. Maybe we can find other problems. Im curious, please let me know what's going on.

jonwilliam · Feb 18, 2009, 06:47 PM

Originally Posted by mygirlsdad77

usually a pressure switch is open or closed. Ohms usually dont have a factor in pressure switches, however, it is possible. Hope one of the other guys will give you some answers.

I would like to know why you are ohming switch. Can you let me know what the furnace is doing. Maybe we can find other problems. Im curious, please let me know whats going on.

Just ohming it out to check it out if it is OK or faulty.

mygirlsdad77 · Feb 18, 2009, 06:55 PM

So you are having problems with the furnace. Not just checking pressure switch for fun? IF you suspect the pressure switch, you could try bypassing it and see if furnace works. You may have to wait until the draft inducer comes on before jumping switch. Please let me know exactly what the furnace is or isn't doing and I will try to help. Does your furnace have a diagnostic led on the board? If you can explain what is happening from the time the thermostat calls for heat up to the time the furnace fails, it would help greatly.

KC13 · Feb 18, 2009, 08:15 PM

Does the switch exhibit any evidence of exposure to moisture? If so, the switch contacts may be oxidized and somewhat resistant.