We have a 2004 Skyline, just trying to figure out if it's a simple fix or do I need a pro. The AC worked fine last year, oil heat still works and fan works, but when the call is made for AC the t-stat (Honeywell wifi) clicks, then shuts down and reboots. I pulled the t-stat and connected the R & Y to make sure it wasn't a bad t-stat and the 3 amp fuse in the furnace electrics box blew. Anyone have any suggestions?

 

Since the fuse blew when you connected the R&Y wires, you have a short somewhere. Most likely it's outside, however if you want to confirm it's outside and not inside, disconnect the 2 wires (they'll be bundled together in a jacket) that run to the outside unit from the furnace. If the fuse no longer blows, then the problem is outside.

Assuming the problem is outside, it's likely one of two possibilities: either there is a short in the wires running from the trailer to the outside unit, or the contactor (relay) inside the outside unit is shorted. The most likely reason is a short in the wires, probably from an animal chewing on the cable.

 

You were spot on Bob, found a section of the LV wire that comes from the furnace board to the condenser outside that was missing some insulation. I separated the 2 wires and checked with a Vohm, then replaced the fuse. When I call for AC now the blower kicks on but the condenser doesn't. It's safe to assume that if the 2 wires could short the system to begin with that there isn't a break in either one of them so I guess I need to research how to test the contactor.

 

So I was sitting eating dinner and had a face palm moment. Along with pulling the outside breaker I also shut of the AC breakers in the panel and... forgot to turn them back on

AC is up and running again, just have to do a permanent repair to the damaged wire.

 

It's possible you're low on refrigerant. Most, but not all, condensers (outside unit) have a low pressure switch that prevents the compressor from running when the system is low on refrigerant. I would suggest the following test.
1) Turn off the 240VAC power to the outside unit.
2) Set thermostat to call for cooling (blower should come on)
3) With a voltmeter set to AC volts, check for 24V where cable from furnace comes into outside unit (usually connected to internal wiring with wire nuts). If no 24V, there's a break in the cable.
4) Check for 24V on the contactor coil contacts (often on the sides of the contactor and use thinner wires than 240VAC wires on contactor)
5) If you have 24VAC at contactor coil, contactor is bad. If no voltage, you likely have a low pressure switch which as activated
6) Check condenser wiring diagram to confirm that low pressure switch is present

 

Thanks again Bob, see my post not long before your last one, it's working again.

 

Glad to hear you got it going. I was typing my reply when you replied that everything was working.

 

I figured, I really appreciate your input!