Intermittent problem with Trane XE900

[diyfan]

Few days ago, I felt no cool air came out of vent, but after while (lot longer then it should be) it seemed to working fine. Yesterday, same thing happened again. Everything seemed to be working just no cool air. I ended up with turning it off. This morning I found something new, when I turned AC on and the outside unit is even spining at all. Then I noticed that the Pepco box (for energy saving)has a little light on. I assume that is when it is working although it should only work during the daytime on extrem hot weather. Anyhow, this might be a separate issue. So, my questions is what could be the problem (intermittent cool air)? And how do I diagnose this issue? This is a 14 years old equipment, worked great.

[millerman]

While using your refer gauges what pressures did you note while the "no-cool" situation was happening? How about your superheat/sub-cooling, what was that reading? When it was running fine what were your psi readings and superheat/sub cooling measurements?

When was the last time you replaced your filters or had the equipment serviced?

[diyfan]

Well I don't really have those fancy tools. But if this is intermittent problem, can I say there is no leak of refregant problem? So, that leads to other possibilities - compressor. How can I tell if it is working or not while condenser's fan is on? Or is there any weak parts can be replaced in compressor that possiblely malfunctions? I don't recall this unit ever being serviced. I should replace filter more often, but will it cause the system totally down or just make it inefficient? Thanks for the reply.

[millerman]

The tools needed to do proper diagnostics aren't fancy just necessary. There are no parts to replace in a hermetic compressor. Checking amp draw from the compressor while running will tell you basically that it is in fact running, high amp draw or low amp draw will tell you how hard its working but thats about it. Clean filters and clean indoor and outdoor coils will make a difference. Many can be fooled by dirty coils and pump a bunch of refrigerant into the system. You should call a pro and at the very least have you equipment serviced. Good luck.

[diyfan]

Thank you very much, those are very good points.

[mark beiser]

Originally posted by diyfan
Then I noticed that the Pepco box (for energy saving)has a little light on.

Congratulations, you have diagnosed your problem!
Is the kickback on your electric bill worth intermittantly not having cooling? If not, have the stupid thing removed.
I'm glad we don't have to deal with that crap here.