Trane XL16i - fuse blowing on ouside unit

[navyjoe]

I have a Trane XL16i. The outside unit is a 4TWX6036C1000AA. It has a 5 amp ATO fuse in the low voltage control circuit that blew last night. The fan runs, but the compressor won't. The Tech came out and replaced it, it blew again. He could not figure it out and is waiting for the main tech to get back tonight and will try again tomorrow.

Based on the diagram this fuse is inline with the red wire from the 24 volt transformer on the outside unit and goes to the main circuit board connector J1.

Any ideas?

[dunkman]

Tell him to ohm out the contactor coil, reversing valve coil, inspect the control board for shorts. Is it set up as a communicating system? Must be, since you have a fuse in the outdoor unit.

[navyjoe]

BTW, I believe the Tech questioned why a 24V transformer outside and one inside. If he disconnected the inside the fuse would not blow and wondered if the orginal installers wired it correctly. My question to him was it came from the factory like that and worked Ok for almost 3 years. What changed last night to blow the fuse?

[dunkman]

What's it paired up with inside? The outside transformer powers the outdoor board and all outdoor functions. The outdoor communicates to the indoor unit via 2 wires.

If it has the standard 6 wire pigtail at the outdoor unit, then the outdoor transformer should not even be hooked up.

[navyjoe]

Tell him to ohm out the contactor coil, reversing valve coil, inspect the control board for shorts. Is it set up as a communicating system? Must be, since you have a fuse in the outdoor unit.

I wish I had the correct answere on that. Don't know if it is a communicating system or not. There is no place for a readout. There is one green led on the outside unit that is flashing a rapid burst but the tech has nothing to read it with.

[dunkman]

2 wires=communicating

6 wires=non-communicating, and the outdoor transformer should not even be hooked up.

[navyjoe]

What's it paired up with inside? The outside transformer powers the outdoor board and all outdoor functions. The outdoor communicates to the indoor unit via 2 wires.

If it has the standard 6 wire pigtail at the outdoor unit, then the outdoor transformer should not even be hooked up.

Inside unit is a 4TEE3F40B1000AA
Outside unit is a 4TWX6036C1000AA
Honeywell Zone controller HZ322
3 Trane XR402 "thermostats" feed the honeywell.

It is using the 6 wire pigtail to control the outside unit. I am assuming it cannot use a 2 wire setup due to the Zone system???

[navyjoe]

2 wires=communicating

6 wires=non-communicating, and the outdoor transformer should not even be hooked up.

Well that may be why the fuse blew. It probly blew 3 years ago and no one noticed until this problem came up and noticed the fuse had popped.

The orginal installer really had a time making it work. The carpenders told me he was on the phone with someone getting directions on how to hook it all up.

I orginally asked for a 2 ton XL16i system for the first floor and was going to install small split units in each bedroon on the second floor. The contractor and Trane installer talked me into going with a 3 zone system instead. 1st, floor, 2nd floor, den(in basement).

[dunkman]

These two threads should be merged together. http://hvac-talk.com/vbb/showthread.php?t=912682

The zone system is not a "communicating system". That heat pump comes out of the box as "communicating." Whoever installed the wiring kit to make it non-communicating did not remove the wires from the outdoor transformer. I don't know how the heck it made it 3 years without issue. Sounds like the original installer messed this whole thing up. If your tech isn't familiar with the 16i he needs to get a copy of the instructions for the "non communicating low voltage harness" I can't remember the part # off the top of my head. We quit using them a few months ago.

[navyjoe]

These two threads should be merged together. http://hvac-talk.com/vbb/showthread.php?t=912682

The zone system is not a "communicating system". That heat pump comes out of the box as "communicating." Whoever installed the wiring kit to make it non-communicating did not remove the wires from the outdoor transformer. I don't know how the heck it made it 3 years without issue. Sounds like the original installer messed this whole thing up. If your tech isn't familiar with the 16i he needs to get a copy of the instructions for the "non communicating low voltage harness" I can't remember the part # off the top of my head. We quit using them a few months ago.

Dunkman
Thanks for the suggestion, butI did not put them together because the 2 questions were not related and it has been my experience when you discuss 2 different issues thing get confused. I do have a addition to the other thread having just talked with Honeywell.

[second opinion]

These two threads should be merged together. http://hvac-talk.com/vbb/showthread.php?t=912682

The zone system is not a "communicating system". That heat pump comes out of the box as "communicating." Whoever installed the wiring kit to make it non-communicating did not remove the wires from the outdoor transformer. I don't know how the heck it made it 3 years without issue. Sounds like the original installer messed this whole thing up. If your tech isn't familiar with the 16i he needs to get a copy of the instructions for the "non communicating low voltage harness" I can't remember the part # off the top of my head. We quit using them a few months ago.

BAYACHP024A WIRING HARNESS

[navyjoe]

BAYACHP024A WIRING HARNESS

Would this, the harness, still apply in a Zone system?

[dunkman]

Would this, the harness, still apply in a Zone system?

absolutely.