HELP! 1PH Copeland Scroll continues to run backwards!

[fastline]

I am not sure if we have reached a point of damage or not but I discovered my own system running backwards today. I heard a different sound at the A coil and instinctively felt the line sets. Liquid line was cold and suction was hot. Compressor sounded different but certainly nothing that would alarm any tech walking up to it.

I have let it rest up to 1hr, it will only start in reverse now, or lets that that is the only way I think I can get such temp results? This WAS a heat pump but I personally cut out the reverse valve so there is no way for that to happen now.

I checked all the wiring and the run cap tests perfect. 35uf on a 2.5T pump. I did not check ESR on the cap but cap tester showed 34uf. I also made sure contact was being made from L1 to the cap.

I am just out of ideas or reasoning here! I have a hard time just cutting out this pump because I don't know what is wrong. I have not put gauges on yet because it is dumping rain right now.

I need a firm way to verify reverse operation and if that is the case, I need to figure out a way for force a reverse (correct) start. I was going to try a little bigger cap just to see what happens. 50+5 but I suspect that ain't it.

[Neddy]

You need to put gauges on. A scroll compressor does not pump if running backwards.

[passandscore]

Seeing as you are dealing with a 1 phase scroll I would have to say that rotation is not an issue.

A tech would know if a scroll was running backwards (3 phase). Its sounds horrible! Watch the attached video for a visual example.

http://www.youtube.com/watch?v=hLXDb8jA-_4

Put your gauges on the system and record some pressure and temperature readings.

After you let the compressor cool down did it start-up okay and produce any cooling?

Another possibility is that the thermal bi-metal overload inside the scroll opened and you are unloading discharge gas back into the suction line.

http://www.emersonclimate.com/asia/en-AP/Products/Compressors/Scroll_Compressors/Commercial/Documents/astp_overview.pdf

[Brian_UK]

Sounds more like a gas shortage, the "liquid" line is cold because the refrigerant is boiling off before it reaches the evaporator. Check for leaks.

[install monkey]

is comp pumping?

[fastline]

Brian is the winner here! I feel pretty confident it ran backwards before right after a power surge but in this instance, the pump did not sound bad. It was indeed out of refer. That actually leads me to my next series of questions. I am no longer suspecting the comp, I am chasing leaks.

I found one big leak at the suction isolation valve at the condenser. No biggy, fixed. Pressured up with a little 134a just as a dry test gas (not running it). System is not holding pressure. Turned down the iso valves and leak is isolated to line set or evap. I sniffed and sniffed with meter on the A coil and and just cannot find it. I am pressuring up to 15-20psi of 134a. It leaks down pretty damn fast.

I am sure there are not too many line set issues so but I really need a good way to find the leak before I tear anything else down.

Question : I do not have Nitrogen but I do have CO2 (BEER!). I know there are some concerns with moisture in CO2 but what is the verdict? Sounds like some use it and those that do never seem to come with the failures that we are warned of.


Any other ideas to source this leak would be GREAT!

[passandscore]

If you are losing pressure fairly fast then you should add more pressure so you can hear it. Make it whistle! I have no comment regarding using CO2. You can search this forum as the topic has been discussed. I will simply recommend using a dry gas such as nitrogen. Is nitrogen not available in your area?

Check your data plates for maximum allowable pressure ratings. Obviously don't max it but be aware of what they are.

[fastline]

I appreciate the responses. It turns out that of all odd things, I have a sewer line in the crawl space that has a slight drip and happened to drip right on the liquid line. Over the years, it actually ate right through the line. I carefully inspected the lines and determined that only a small area was compromised so I added a band of silver solder over the leak and all the way around the copper. I also move the line set so it will not happen again.. Frustrating.....

[Brian_UK]

Glad you found it and thanks for updating us.