[guru1208]

Hi,

Need some guidance. Air handler works fine but contactors will not pull down the condensing unit.

[hvac1000]

You need a 24 volt signal circuit to activate the contactor in the outside unit. Start at the outside unit at the contactor and trace back to the inside to the air handler to find the defective part.

[Stratmando]

Transformer in ir Handler Converts 240 volts to 24 v. goes to thermostat(RED)
When set to cool RED touches Green for fan relay, and Blue out to compressor contactor.
If when set to cool, No 24 volts at contactor coil.
Then Go inside air Handler and troubleshoot from there.
24 volts should be present at secondary side of transformer, No matter what thermostat set to.
Transformer Fuse?

[JackT]

Don't go by the color code, not everyone uses the same thing, most will use the yellow wire that should be connected to the Y terminal. As hvac1000 said, start outside and work backwards until you have 24 volts. Most likely if it was a fuse or transformer problem, the air handler blower wouldn't come on at all.

[Stratmando]

Like JackT says.
I wrote blue, meant yellow, Thanks, also with air handler kicking in, transformer is good.
I will come back after recovering from flu.