I replaced three transformer on my air handler on yesterday, the last one ran for about thirty min. then it burned out, I looked at the wiring to see if I had frailed wire anywere but I did not, can anyone help with this problem?

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Originally Posted by drehou

I replaced three transformer on my air handler on yesterday, the last one ran for about thirty min. then it burned out, I looked at the wiring to see if I had frailed wire anywere but I did not, can anyone help with this problem?

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It could be the transformer you are using as a replacement is not capable of producing the required VA for the system. I would check this first. Next you will need to check the components powered by the transformer for short circuits etc

Note: Adding a small low voltage designed circuit breaker or a fuse holder and fuse will prevent you from burning out the transformer while you are servicing the system. The fuse is cheaper than the transformer.

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Originally Posted by hvac1000

It could be the transformer you are using as a replacement is not capable of producing the required VA for the system. I would check this first. Next you will need to check the components powered by the transformer for short circuits etc

Note: Adding a small low voltage designed circuit breaker or a fuse holder and fuse will prevent you from burning out the transformer while you are servicing the system. The fuse is cheaper than the transformer.

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What type of fuse would you recommend?

The problem could be a short in the low voltage wiring to the compressor or to thermostat.
Could also be shorted windings on one of the relays/contactors coil.
I take it does it on cooling will exclude the heating relay.
Leaving Blower or Compressor Contactor/relays.
What is the VA of the transformer.
May just need more VA's

My transfomer I have is - JARD CLASS 2 50/60Hz
TF402424-B51C84 K
PRI WH BK RD OR
B-10 COM 120 208 240V
SEC BL-COM YW-24V 40VA