Hello,
If someone can point me in the right direction, I would appreciate it. I have a heat pump and whenever I try and call for cool, neither the inside or outside unit comes on. I am a seasoned maintenance guy with electrical experience, so I feel comfortable trying things, but I just want to be pointed in the right direction.

Thanks in advance for any assistance

 

Check the fuse on the control board in the furnace.

 

The fuse shows that it is good. After I posted, I read one of the other posts about having a bad transformer. The symptoms that were in his post sound alot like what I have. I am going to check the transformer next and see if I have voltage in and out. From a logical standpoint, this would make perfect sense why neither unit is working and hopefully this is the case.

 

Normally the fuse blows before the transformer but in the case of an AC surge or spike..... the transformer can open without blowing the low voltage fuse. Check for 120/240v to the transformer. Remember, there is usually a switch on the service door that cuts all power to the unit,

 

Exactly what Pete said. Check simple easy stuff. You haven't mentioned it...but did you check breakers? Is it in COOL mode (if it has that). Verify power to stat if a modern LCD display type (easy, just pull batteries if equipped). Did it ever work? New to you system?

 

 

rainy??? What do you mean?

 

 

Now information. I have checked the entire 24 volt circuit from thermostat to outside unit. Whenever I would call for cool on the thermostat, I would blow the fuse. Whenever testing the outside 24 volt wires, I had all wires connected on inside unit, but all 24 volt wires disconnected from outside unit. I connected each set one at a time and would check and see if the inside fan was still running. Whenever I connected the yellow, it blew the fuse. I decided to check for a short in that wire, so I took a spare wire, connected at the thermostat, inside unit, and then connected at outside unit and I still blew the fuse. My question is what could I check now.

 

The Yellow wire is the one that goes to the outside unit (condenser/compressor). Since you've already tried a new wire, you can rule out shorted wiring from house to unit (animal chewing on wires). It's possible that you have a bad contactor. The contactor is a relay that turns the outside unit on/off. When the thermostat calls for cooling, it connects the Y terminal to 24VAC. The 24VAC activates the coil on the contactor, pulling down the contacts, turning on the outside unit. Sometimes the coil shorts to ground, thus effectively shorting out the 24VAC. To confirm, remove both control voltage wires from the contactor. They are normally connected to the side terminals on the contactor. Before doing this, turn off the 240VAC power to the outside unit. There should be an electrical disconnect near the outside unit. If the fuse doesn't blow with the wires disconnected from the contactor, the contactor is bad. You can pick up a new one quite cheaply.

 

 

Unfortunately, you have me confused as to what you've tried. I would suggest you try disconnecting wiring in the following sequence until you find where the problem is:
1) Disconnect wire from Y terminal on air handler that goes to outside unit
2) Disconnect wires coming from house to outside unit where it comes into outside unit (wire nuts)
3) Follow wiring inside outside unit and disconnect wiring from any devices (pressure switches, timers, etc.)
4) Disconnect wiring from contactor coil

 

 

4. What 24V wires did you disconnect in the outside unit?
5. Where did you start connecting pairs of wires, in the inside or outside unit?
6. You ran a new wire from the Y terminal on air handler to outside unit? If so, did you disconnect original wire (from Y to outside unit) first?

 

 

Try disconnecting the wire that's connected to the Y terminal on the air handler (indoor unit) that goes to the outside unit, leaving everything else connected. If I'm understanding correctly, the fuse should not blow. Please verify this is true.

 

Currently, I am not there. I will try this is just a while and will respond.

Thank you so much for the responses

 

 

OK, that's good. You've narrowed the problem to the outdoor unit. See my earlier message (#12). You've just done step 1, so start with step 2). Let us know how far you get before the fuse blows again.