trane rtu

[emtim]

worked on trane .when in test mode stage one and two not coming on ,no failure codes on given ,lpcs and hps closed ,no froststat ,economizer working correcty .have 24 volts going through lpc ,nothing on hpc ,looks like main rtm board ,any suggestions.

[toptwo]

what do you mean nothing on hpc is it closed or open.

[emtim]

hpc switches closed .do not have 24 volts into switch ,schematic shows it is from a k1 contacts from board.

[rundawg]

Post a model number so we can look at the wiring diagram.

[lancerbomb08]

is this the model where you jump the two terminals to send into to test mode?

[hoyle]

I ran into something similar about 2 months ago before you condemn the board check the compressor overload the circuit gos through that and also depending on the model there is also a little hard to check switch behind the compressor disconnect that proves the breaker is on. Good luck

[freezon]

Don't know what model you're working on, but that happened to me on a Voyager once. It had 2 air-pressure switches in the fan compartment, one of which was locking the cooling out. One switch was dirty filter, the other I don't remember now, maybe fan proving.

[emtim]

model ycd3014haca serial 452100617d

[jcater8127]

IF this unit has the older UCP board - See if you have at least 5v DC at terminals Test 1 & Test 2 (Located on LTB). If you don't have the voltage there. Unplug the J4 plug on top of the UCP board, then check and see if you have 5v DC between the two pins J4-1 and J4-2. If you don't have your voltage there you probably have a bad board.

If this is the UCP board and you have your 5v DC at the test terminals. You should then check for input problems of the standard zone sensor circuit or CTI circuit. Remove the J7 plug on the UCP. And at terminals J7-8, J7-9, J7-10, and J7-11, check for 5v DC at each terminal to ground. If you don't have 5v DC at all points your UCP is bad.

And the last part to check on the UCP is testing for input problems of the programmable sensor circuit or TCI circuit. You should remove the J6 plug on the UCP. At terminal J6-6, the voltage to ground should be 30v DC +/-5v DC. If it is lower than this, the UCP is probably bad.