Air Conditioning - 5-year old Carrier AC not cooling--compressor works (I think)

The outside unit fan works and it sounds like the compressor is on as well. The larger copper tube (1-inch?) does not feel very cold and the smaller tube (1/4-inch) does not feel warm. I rinsed the coils down with water and cut the breaker on-off.

Inside the house, I replaced the extremely dirty filter. The inside unit is cool (54 degrees) near the coil. I sprayed the coil with 409 in case they were dirty. I did notice there are four small-diameter (1/8th inch?) tubes that ice up shortly after the unit switches on. These four tubes go from the coil to the 1/4-inch tube which goes to the outside unit. Is this normal? The blower is spinning--why would it not blow the 54-degree air throughout the house? Should the air be cooler or could it be that enough cool air is not being produced at the coil? The vents in the house are blowing approximately 80-degree air with good force. Any suggestions on what I should check next? Capacitor? Contacts? relays?

Any help is greatly appreciated--I'm determined to at least have a working knowledge of this system before calling a technician.

Hi:

Now that's a very good description of the problem! I'm thinking that your system is probably low on refrigerant which would indicate a leak or leaks. It's also possible that the orifice at the indoor coil which controls the flow of refrigerant to the coil is restricted. You'll need to call a professional service company to come out and check it out for you. Let us know what they find.

Like John said the icing up sounds like it could be low on refrigerant, or you could have an internal restriction. Is the indoor fan running? Where are you reading the 54º at? Do you have good airflow out of the vents?

Thanks for the replies. The indoor fan is running, I'm reading 54 degrees on the aft side of the coil, and there is good, strong air coming out of the vents. If the refrigerant is leaking, would the leak be at the inside coil since that is where it is icing up, or not necessarily? Which line carries the refrigerant to the indoor coil, the 1/4-inch or 1-inch diameter copper?

The small line brings it to the evap and it then picks up the heat from the house and takes it out to be expelled at the condensor by the large line.

It's hard telling where a leak may be. The inside coil freezes up when a unit is low on refrigerant due to lower evap temp and the condensation on the coils begin freezing.

If you've got good airflow through the coil and it's freezing up it's time for a pro to look at it. They will need to put a set of gauges on it to see what's going on.

This morning, after replying to some posts, I went to work. The first job I had was a 3 ton split system that cools some offices. It was interesting that it exhibited the same exact symptoms as your a/c. It uses an orifice for the refrigerant flow control and I found some debris obstructing the refrigerant flow at the orifice. I cleaned it out, blew the lines out a couple times, and installed a filter-drier on the liquid line coz the system didn't have one. I got it running again and had to add a couple pounds of refrigerant to get the charge just right. Although the compressor is pumping fine, it sounds terrible. They want a quote to replace the compressor on a pre-emptive strike basis.

This board is awesome--you guys have been a great help. Where would I find the orifice? Is it at the connector where the 1/4-inch copper tubing and the 4 capillary tubes are joined? Even though I'm having a tech come out tomorrow to look at it, I'd like to be armed with as much knowledge as possible. One tech I spoke with said the cost for refrigerant is $12/lb, and my unit should take about 9 or 10 lbs. He also said if it is leaking refrigerant, he may not be able to find the leak. Is that acceptable or should I insist on finding the leak?

Yes, the orifice is located right at the connection point you describe. The people you spoke to are just preparing you for worst case scenarios. The tech should have an electronic leak detector which can locate the smallest of leaks, however it takes time. There is also available a methodology of injecting a dye into the system and then, the next time it needs refrigerant, the technician uses a special light to look for a leak. If the they make a good faith effort to locate a leak and can't find you it, might consider the dye. You really do need to have the leak located and repaired because running the unit with a refrigerant shortage is bad for the compressor. I hate to have to tell you this but Carrier units are bad for springing leaks on the cooling coils. If that is the case, you're looking at a new coil which is an expensive repair. Btw- it is not illegal to just keep refilling a unit your size with refrigerant.

I had a tech come out and look at my system. Freon pressure measured 20 PSI, indicating a leak. He thought the leak may have been at the accumulator (outside) judging by the rust, but the soapy water test showed it was okay. He then did the soapy water test on the inside coils, on the areas that could be seen that is. No bubbles there either. He determined the leak must be elsewhere in the coil and it would be difficult to find. His recommendation was to replace the inside coil at a cost of $1050 (includes freon). I was surprised that he didn't have a leak detector and I've heard negative comments about using dye. Does his sound like a good assessment of the problem? If so, I have plenty of experience brazing copper pipe--is there somewhere I can purchase a coil for the unit and install it myself? I think for now I'm just going to have it re-filled with freon and hope for the best. Including labor, the tech that came out today wanted $315 for 7 lbs of freon, another tech I spoke with will charge me only $159. That's a no-brainer.

I disagree with the assessment because he's guessing about where the leak is. [assuming the problem is a refrigerant shortage] However, in his defense he may be going on experience because Carrier's are bad about the indoor coils and accumulators springing leaks. Some Carriers had a 5 year warranty on the indoor coil so you may want to look into that. He should have used an electronic leak detector, the soap suds will only locate large leaks. Did the guy raise the pressure somehow for leak testing? 20 lbs. of pressure is nowhere near enough to leak test with. Also, did he check the high side pressure? What was that reading? I'm thinking you may want to call someone else.You might be able to replace the coil yourself but how will you recover the residual refrigerant, evecaute the system and charge it properly?

PROBLEM SOLVED! The tech that came out today immediately found the leak. First he filled the system with refrigerant, then checked the parts around the outside coil using soapy water. Then, after accessing the inside coil he immediately heard a leak. Within a minute he found that it was in one of the small capillary tubes at the inside coil. Two of the tubes were secured together with a cable tie. Apparently the constant vibration caused it to eventually wear a hole in one of the tubes. He then recovered the refrigerant, soldered over the leaking tube and the other tube as well, then re-filled the system. Two hours of work 7+ lbs of refrigerant--all to the tune of $147!

Thanks for all your help and advice.

Sounds good. The first guy couldn't find a leak that big? I trust that # 2 guy put on a new filter drier and evacuated before recharging?

I don't think he installed a new filter drier and I'm not sure what you mean by "evacuate" the system. What harm would it cause if he didn't do either of these?

Standard prctice for me is any time I have a system open I replace/install a filter drier- a devce with 2 functions. First is to trap any debris that may be circulating and second is to absorb/adsorb and hold moisture. To "evacuate" is a process of using a vacumm pump to remove moisture from the interior of a system. With the evacuation [sometimes refered to as a/the deep vacumm process] process the actual goal is to "dehydrate" the system interior as well as remove non-condensable gasses. Anytime a system has been opened to the atmosphere, standard practice is to evacuate to a level of 500 microns and also do a blank off test to prove the work. Moisture inside the refrigerant circuit is bad news. If you want to learn more, go to www.jbindustries.com and www.yellowjacket.com You'll have to root around the websites to find their technical literature sections.