Trane YCD240 rooftop unit troubleshooting help!!!
I'm working on a Trane YCD240 RTU. this unit had been turned off for very long time 3+ yrs. Now customer need it. here is the problem
Unit got correct power going to it, turned it on. It will not do anything, nothing run. LED light on the control board lit up. Shorted Test1 + Test2 for test mode, but it will not do anything... Checked voltage across test1 and TEst2 got 1.9 VDC. (it should be around 5 vdc). Checked wiring, all seem ok...I'm guessing control board is bad... what do you think? need help..
Does it have anything attached to its "Emergency Stop" terminals? And if yes have you tried jumping them out?
Disconnect J6 plug and try test mode and check LTB 16+17 for emergency stop.
does the unit have pressure? Maybe one of your safeties is open
should still run at least heating or cooling if only 1 safety is open... I.E. 2nd stage high pressure open and non of 1st stage is open 1st stage should run...
I have never seen a good UCP that would not go into test mode.
Originally Posted by DNMechanical
If I were there, I'd play with it, but without being able to do that, I'd lean toward a board.
When you jumper test 1 and 2, does the red LED start to blink?
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2 Tim 3:16-17
RSES CMS, HVAC Electrical Specialist
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They're not that difficult to run checks on. Any reason why that board would be bad?
Down time shouldn't kill them. They're not avocados.
Test should at least give you a fan if nothing else.
Checking to make sure it has pressure is a good idea. Also on the older boards there was a 24v board mounted fuse
They are 3 amp slow blow and they do go out from time to time.
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