Trane troubles

[ncboston]

Any service facts for:
YCH181E3LBBB
114510138D

I have 24 volts between c&g, but no indoor blower coming on. LED on steady indicating no problems. Before I condemn the board i want to verify that nothing else but the board could be causing the blower to not operate.

[sgagne199]

U got voltage at blower motor

[ncboston]

No 24 volts at contactor. Wondering if board is bad and k6 relay not closing or if the board might not be passing lv for a different reason. But to answer your question, there is high voltage present at the contactor.
I'm pretty sure it's a bad board, but I want to make sure nothing else could be telling the board to not pass 24 volts to the contactor.

[ncboston]

To the mods,
thanks for moving.

[local553]

make sure phase is right,they have monitors on them.

[ncboston]

The kicker is, this thing was running. I opened the disconnect, replaced filters, closed disconnect, and no blower. No wires moved, nothing.

[Chris_Worthington]

The kicker is, this thing was running. I opened the disconnect, replaced filters, closed disconnect, and no blower. No wires moved, nothing.

Sabotage, you broke it !! :whistle:

[Chris_Worthington]

Tied into a Trane EMS by chance?

[ncboston]

Sabotage, you broke it !! :whistle:

I'm in trouble now.

[Jerry Jessup]

I ran into this type of problem just 3 weeks ago on a Trane unit. Does the unit have an economizer?

[supertek65]

smoke detector???????????

[ncboston]

I ran into this type of problem just 3 weeks ago on a Trane unit. Does the unit have an economizer?

Yes.

[ncboston]

smoke detector???????????

No fire alarm system or smoke detector tied in.

24 volts enters rtrm board, but does not bring on IDB.
I'm thinking either board is bad, or something that the board looks at is bad.

[supertek65]

is this a model that you can put your meter across a couple terminals and determine which mode the unit is in and if there are any alarms?
the only things that would usually keep a blower off is smoke, freeze or un occupied setting?

[ncboston]

no. I have 24 volts across g & c coming into the rtrm board.

[supertek65]

looks like you have it figured out already?
I will read some IOM stuff and look through the reliatel book!

[Jerry Jessup]

The Trane unit I was working on had the same symptom. I also thought it was the main control board at first, but after some reading I found that I had a faulty economizer board. I purchased a new economizer board and unit quickly come online.

[Jerry Jessup]

One way to test is to turn off the unit, unplug the economizer board plug from the main control board and then turn the units disconnect back on. If the blower comes on then replace the economizer board. The board costed us $$$$

[Beacon Tech]

The boards usualy have triacs (electronic switches) for the output relays. Can you remove the output wires at the RTM going to the fan output and see if you have 24 volts. If you have 24 volts at the board and lose the 24 volt when you put the wires back on, the triac is bad and you have to replace the board. Can this unit be viewed with Rover software and do you have Rover? As someone said earlier, the economizer or the connections may have a problem. If you still have the bypass plug for the economizer, you can try plugging that in and see if the fan starts.

Good luck

[timebuilder]

If the unit runs in TEST (including blower) the main board is good.

In that case, it will be the econ board.

[supertek65]

he has said a dozen times!
he has 24 volts across c & g!!!!!!!!!!!!:putergreet:








If the unit runs in TEST (including blower) the main board is good.

In that case, it will be the econ board.

[supertek65]

if you check the diagnostics or on most of them
ltb1-6 to ltb-9 etc you will see what mode and if there are alarms!

that should tell you a lot!

but it sounds like if you got 24 on c and g everything is perfect!





If the unit runs in TEST (including blower) the main board is good.

In that case, it will be the econ board.

[timebuilder]

he has said a dozen times!
he has 24 volts across c & g!!!!!!!!!!!!:putergreet:

He did.

When someone says they did some tests on a Trane, I often think they may have removed wires from the contactor, and are reading through the snubber circuit. I would need more info to understand exactly what steps he has taken.

I like to put the thing in test to see how it reacts. It can separate the sheep from the goats, and eliminate false readings you can get by looking at an output that has no load: showing a false reading.

If C and G mean he is using a CTI, and C is common and G is fan, we can eliminate the main board as an issue by just stepping through test mode.

[supertek65]

LOL!!!

you are correct!

test mode tells you alot!






He did.

When someone says they did some tests on a Trane, I often think they may have removed wires from the contactor, and are reading through the snubber circuit. I would need more info to understand exactly what steps he has taken.

I like to put the thing in test to see how it reacts. It can separate the sheep from the goats, and eliminate false readings you can get by looking at an output that has no load: showing a false reading.

If C and G mean he is using a CTI, and C is common and G is fan, we can eliminate the main board as an issue by just stepping through test mode.

[timebuilder]

LOL!!!

you are correct!

test mode tells you alot!

That's why I like it.

No resistor box needed. Just a jumper and a little patience!

[Texas-Tech]

If the unit fails to initiate the complete test mode, the rtrm or ucp whichever it has is bad. I have had some fail the test mode but reset the power and retry they worked. Trane tech support told me years ago if the board fails the test mode it's bad.\

They will turn on the outputs no matter what. On the lennox units you can disconnect both the high and low pressure switches, put in test and the compressors will still come on.

[Trehak01]

try bypassing the board.

[ncboston]

Meant to update Friday. I put a new board on friday and everything is good now.
Thanks for all the input.

[gregp]

now 'fess up. What did you do to destroy the board in the first place? :grin2: