Troubleshooting DC volt Roof Top Units
Hi! I hate HVAC!LOL
Went on a roof top unit today and it was a DC system.
Somebody most of been there previously because there was only a white,yellow and brown wire connected to the control and the fan was running all the time. So I did not really notice this till later. So I put my gauges on and pressed the contactor in and the CFM came on and the compressor. The low side pressure dopped to like 10 psi and the high side raised a little. I think it is a stuck closed TXV. Or blocked liquid line?? Has to be a TXV issue? Any ideas?
Lucky they had 2 units. So I put the rest of the t-stat wires back like the other unit ans still nothing. No error code or anything. Is there a website or something on how to troubleshoot DC circuits on rooftops? It had on the schematic some weird wordage where the t-stat wires belong.
It was a TRANE
Please if you have any suggestions!
I never came across DC systems to much.
Put a CTI board in it and you can then use a conventional t-stat.
Nemo me impune lacessit.
How much blood do I have to bathe in to get clean?
Don't look down on anyone unless you're helping them up.
If your here for DIY then...
Originally Posted by hvac20000
Do it yourself...
Read the site rules. We cant help you even if we wanted to.
Gotta have the right tool for the job!
Where is all the stuff MADE IN THE USA?
"Thats what we do Troy. Incredible, Invisible, Imbelivable things. We are an Unseen, Unknown, Unvincible fraternity of craftsman.."
You can buy a service tech manual from yor local trane parts dealer, that will tell you everything you want to know.
If I would of killed my wife when I first met her, I'd be out of jail by now!
1- if you hate hvac, why are you dikking with the equipment
2-what are you doing mashing the contactor, not knowing what is going to happen
3-get off the roof and call a contractor that is capable of working on it
It`s better to be silent and thought the fool; than speak and remove all doubt.
First off that unit has Reliatel, so it has conventional terminals you can use. Second, the odds of that unit even having a TXV is slim. Your model number is too short to know for sure, but TXV's were factory options on those units.
Dude! Do not be ignorant! I am sure you have been on a CARRIER,LENNOX,RHEEM unit you were not able to fix. Do not be an pud and post crap like this. This is why we have this hvac-talk website for problems you come a cross that you cannot figure out. Maybe you should try helping others instead of being a jag off. I put a LOL in hvac to be sarcastic! Meaning you come across once in a while **** you dont understand!
I will bet you that you are the one that cuts down other techs and kissess the boss azz! You know what I try to help other techs and answer there questions on my NEXTEL not to get them in trouble. I hate techs like you. I have been doing this for 13 years! You pud! I hope you do no not treat others like this! You must be a KNOW IT ALL?
Last edited by hvac20000; 05-19-2011 at 09:05 PM.
Reason: Added to explantion
Here is a another azzhole! Look at my other reply! NOOB!
It`s better to be silent and thought the fool; than speak and remove all doubt. YOU! GOT! ISSUES!
What do you mean? What can i do?
It does have a TXV I did verify this. Thanks for your time.
Another reply said a CTI board where can I get this to chancge to 24V AC instead of a DC circuit!
Where can I get a CTI board? I can convert to AC?
How about the indoor fan on and the suction pressure drop.
Thanks for the info. Been out for 2 years in the biz and would like to make an impression.
Man I am trying to keep my job. What DIY rules?
The commercial board seems abit more lenient about dyi posts. But your coming off in a bad way.
With that said there were two generations of boards Micro and Reliatel. Your unit should have a Reliatel board. It should have conventional terminals that you could use to verify operation with a conventional thermostat. There are also test terminals that can be used. You can't properly checked the charge, while holding a contactor in, let alone the danger behind that. I would start by not worrying about the controls for now. Put that unit in test and properly check airflow, followed by properly checking charge.