I made a service call this morning, The complaint was there is excessive water around the condenser and the system does not seem to be cooling proper lalely, she had someone else do the cooling inspection this year, that person told her that he had to add 1lb of refrigerant. I found a 60 degree WB, amb.= 88, SLT= 41, SLP= 64, HP=225, the compressor [scroll]is sweating almost all the way to the top, I checked the filter=[new] and the supply is blowing strong Idid not have any way to check the velocity but it was strong enough to lead me to believe toe coil is not matted, the condenser is clean, it has a non TXV metering device the LLT was 100. Before I checked the condenser the drop was 12 degrees I was thinking under charge so I added some refrigerant, the pressures increased but the SLT dropped[I understand how this works]so Iam thinking there is too much liquid coming back to the compressor so I recovered some of the gas which did cut down on some of the condensation on the compressor, The drop was then 18 degrees, SLT=44 SLP=62-64. was I correct, is there anything that I should have checked is there anything else that causes the com.to sweat?
IMHO, this post thread should be on the pro site. I will be happy to explain reasons if you really think it is necessary.
if u are not a homeowner post this where it belongs on pro side but it sounds like u are a homeowner tring to servive ur a/c
tball... what would be the thought process that brought you to you "thinking it was undercharged"?
John, lets see if slowing tball down a bit will help him figure his dilema out.
the pressures is what I kept thinking about, The house was comfortable and the suction pressure was [well in my opinion anyway]low there was only 4 degrees of superheat. I have always been told that when the compressor is sweating the system is overcharged but the pressures did not lead me to that conclution.
I know that an undercharged unit will have a high superheat, to be honist I added the refrigerant in case the system was low, then when that dod not work I recovered some of the refrigerant which increased the superheat and increased the drop.
Ok...but there are other things that can cause low suction.
Lets look at the numbers you gave us.
225 head, LLT of about 100. 225psig of R-22 has a saturation temperature of roughly 110 degrees. Your liquid line was 100. This means you have 10 degrees of subcooling.
Would you say 10 degrees subcooling is a flooded or starved condenser?
I'll answer on your behalf, its flooded. If it were starved I wouldnt be subcooling. Really this one is just pretty well loaded.
Now how about the evaporator. You said you had about 4 degrees superheat. Is that flooded or starved?
Again, I'll assume you know its flooded.
Now, looking at both coils and relizing they are both flooded, it should be clear that there is simply too much refrigerant in the system which means its overcharged. Is that the only problem? Well maybe, maybe not.
So you recovered some refrigerant and the SLT went up as expected but the suction pressure went down to near freezing. This should be an indication to you that there is a low evaporator load. Low load can be several things including low airflow or low return air temp. If you then read the return temp to be 74 degrees, you can safely assume it has low airflow. Now you need to reevaluate the low airflow. I suggest to you see about some training in airflow diagnostics along with some more review of how to determine system charge.
Far too many techs grab a can of freezone whenever they go on a service call. More often than not, they either complicate the problem or create another one all together.
[Edited by docholiday on 07-24-2005 at 07:51 PM]