Heil 1320548 limit switch
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If you have your controller lights blinking four times there is a good chance you have a bad high limit switch (check your controller to make sure that is the right flashing code). If the high limit switch is the problem replacing it is only a five minute job. Unfortunately the code for the high limit switch does not always mean that the switch is bad. It could be simply that your air flow is blocked so check that first.
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