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Heating, Air Conditioning, Fridge, HVAC/continues to blow disconnect fuse


QUESTION: I have two units. Mammoth air conditioners. They are TXV heat pumps. I came to the unit. Found a bad fuse and replaced. They immeadiately blow the fuse right away. ONE fuse on a three line disconnect.  The only think I found off was a burn mark on the control board. Everything else checked out good. Could a bad control board cause the fuse to blow?

Can you help. These are two units.

Thank you.

ANSWER: it would be easier to diagnose with a Model#, voltage requirement.  it is possible for a PC board to blow a line fuse if the transformer on the board is shorted.

---------- FOLLOW-UP ----------

schematic for unit
schematic for unit  

QUESTION: thank you for your answer.  I know that some of the boards have transformers built in, there is also a secondary one on the side of the unit.  I can attach the image for the schematic and the model number.  I am not sure if I sent the image of the board to you. It is right on the Line voltage resistor.  If you didn't get it I will try to resend it.

according to the wiring diagram, once power is applied to the unit, the only components that will affect the fuses (without the thermostat calling for cooling)are/probably the control transformer.(marked-"transformer" on the diagram.  To establish what-for sure - 1.  turn power off. 2. disconnect the 2(smaller) wires leading from L1 & L2 (of the main power block in the unit) and going to the transformer. turn the power back on.
let me know what happens.  

Heating, Air Conditioning, Fridge, HVAC

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