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honeywell L4064t fan and limit control on oil horizontal furnace. has two wires coming from ff terminals on cad relay and plugs into center of fan&limit control. does this start fan before temp. dial turns? can you replace with standard L4064 or does it have to be that style for areason?


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505

    I can't imagine that ff goes from the primary to the fan/ limit. Please re check the wiring. For oil, all wires to/from the fan/limit are line voltage.

    You can't replace with standard here's some of the reasons:

    http://customer.honeywell.com/techlit/pdf/68-0000s/68-0024.pdf Pages 9&10 for starters

    There was an error rendering this rich post.

  • Paul_69
    Paul_69 Member Posts: 251

    there are line volts like regular limit,there is a 8184m primary control and the wires i am talking about that are plugged in to two terminals on f&l are coming from f on relay and other side to a low volt wire on 8184m. my thoughts are that this may start f&l earlier than waiting for temp. to turn on blower because of horizontal furnace. ?? what can you replace this with when it fails?its definitely a different control than standard type. thx
  • billtwocase
    billtwocase Member Posts: 2,385
    I would say

    that your furnace is an Olsen. They are the only unit that I have found that control on. You need to order it. 
  • Empire_2
    Empire_2 Member Posts: 2,343
    Hi Paul.

    Your fan/Limit control that you are referring to has 2 terminals at center of control.  This is actually a heater which assists the fan upon a call for heat.  Since you are working with horizontal, the heat assist or the terminals in the center must be connected.  Generally this is a 24vac circuit that when a call for heat comes, the heater starts to heat up, faking out the control.  Since you are working on Horizontal, these heat assist are required.  Also, when looking at the fan and limit, a break away tab can be removed for 24/120vac.  The tab links fan and limit sides to the same 120vac.  By cutting or breaking away the tab, you isolate each side.  Limit in you case usually disrupts the control circuit, but can also kill the transformer, depending how you hooked it up...

    Mike T.
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