Original message
| digitelcej
 |  "Fan Runs All the Time"
, posted Sat 13 Dec 22:26  
Hi, all. Thanks for the help on the low voltage transformer. It was bad and I bought a new one (STEVECO 90-113 Fan Control Center). Replacement transformer came with a White-Rodgers RBM Type 91 Relay. Old relay had three wires (Black, Yellow, Red). New relay has three wires (Black, Brown, Red). Old relay black went to a black/red wire (directly to fan),Red went to a large red wire (to fan/limit switch), and yellow went to a large charcoal wire (directly to door shutoff switch and ultimately to 120 VAC Black from supply). When I connect the brown wire in place of the yellow wire, the fan runs all the time (thermostat "on" & "auto"). When I reverse the black and brown wires, the fan also runs all the time. In all other color connection combinations, the fan does not run at all. My sense is that the thermostat or some other device is malfunctioning. Old thermostat had common ("C") connection to TR side of TH ---TR switch and "W" (Heat) connection to one side of limit switch. These connections were made on the new transformer as well. Any ideas as to why the fan runs on both "on" and "auto"? TIA.
CEJ
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Replies:
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| xenos
Webmaster 
| "Re(1):Fan Runs All the Time" , posted Sat 13 Dec 22:46
I am unable to locate a diagram for a 90-113. What you need to look at is the fan must be powered through the normally open contact. And the fan limit through the normally closed.
Also check your fan limit and make sure the button is not pushed in.
WARNING if you power 2 speeds at the same time you will blow your motor.
See if you can find the relays on white Rodgers web site.
http://www.whiterogers.com/contractor/ptech/ptech_home.htm
Xenos.
The best way to escape a problem is to solve it.
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