Heat Pump problem

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  #1  
Old 04-17-03, 06:19 PM
PalmatBH
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Heat Pump problem

I have a carrier heat pump and I am experiencing poor cooling. Both fans come on (interior and exterior) and the air is slightly cool. I cleaned the interior coil fins, removed the air filter (temporarily for testing) with no change. I spoke with a guy on the phone today and described to him that the narrrow copper pipe that feeds the interior coil is cold. he said it should be warm a foot or two from the coil. Does anyone have any ideas what is wrong? How much it might cost to fix, what is fair?

thanks
 
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  #2  
Old 04-17-03, 08:19 PM
firsthvac
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You don't give much information about your unit and system but here are some common causes to units not cooling well:

Dirty filters and/or coils (you've cleaned the inside coil and changed the filter but is the outdoor coil clean too?)

Open ductwork...Have you checked to make sure you're not getting airflow into the system from an outside source? Found a couple of these this year already myself.

Low refrigerant level, poor compressor performance and airflow problems due worn fan motors are other causes...for these you would be better off to call a service company to determine exactly what the problem is. The cost is dependent on what the individual company charges for a service call, hourly rate and materials but expect to spend a minimum of $75-100. Not only do service prices vary widely, so does the experience and reputation of service companies. Therefore be wise...shop around by phone and be sure to choose a licensed, reputable, experienced service company.
 
  #3  
Old 04-17-03, 08:28 PM
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Thumbs down Compressor replacement...

Your compressor may have failed. There could be a refrigerant leak, but this usually has a low pressure control to prevent that. You need to see if the compressor outside (Like a big black can) is running. Is the outdoor coil clean? It's not the problem though (YET) because if it were dirty the skinny line would be hot. I suspect there is a leak or the compressor is dead. The unit is trying to run the compressor, I know this because the outdoor fan is running and it is wired to the same contactor as the compressor. Kill the power and look for burnt wires and inspect the contactor. You'll need a 5/16" nut driver.....
 
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Old 04-18-03, 04:59 AM
PalmatBH
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Thanks for the replies. I am a service engineer by trade (different field - scientific instruments) and I am happy to dig in with a volt meter or any other tests you might recommend.

I have cleaned the exterior coil using a powerwasher. It is free of obvious debris. The coil is on three sides of the outdoor unit. I am not sure if this is the preferred way of cleaning this coil but it was the easiest without having to disassemble the unit. Do I need to go inside the unit and if so what is the best way?

I would like to check if the compressor is working but I suspect that it is since the small pipe is frosting at the interior coil. Can this be happening with low refrigerant or bad compressor? Is their a way for me to check the refrigerant level or if the compressor is turning on. I suspect I will have to remove the top section where the fan is located, disconnect the fan, gain access to the compressor, turn on the unit for a short time, and feel if the compressor is warming up.

FYI - the unit is a Carrier Heat Pump 38YKB.

Another note - I am trying to get a handle on what is wrong with this unit. I am concerned about what I am hearing on the telephone. The company was unwilling to provide me with an estimate stating they have no idea what the problem is. Their rates are $80.00 for the first 1/2 hour and $40.00/ quarter hour after that. I am very uncomfortable paying that kind of money with an open ended agreement. I finally pinned them down and they said most calls go from $500 to $800 (ouch!). They said that the refrigerant is $25.00 a pound yet could not tell me how many pounds I would need if a recharge is necessary. Any ideas on how I can find out how many pounds of refrigerant is needed?

Thanks again for all your help.
 
  #5  
Old 04-18-03, 05:04 AM
PalmatBH
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I forgot to ask - where could a possible open duct to the outside be located? I have lived in this town house for 14 years and I am not aware of any opening to the outside.
 
  #6  
Old 04-18-03, 06:12 AM
firsthvac
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Thanks for the x-tra information. With the coils being cleaned and the compressor obviously running (as indicated by the frost line) there is not much else you can do to answer your questions.

It is true that repair services can't just give you a cost on the repairs because they obviously don't know what the problem is without checking it out. Still, the prices quoted were a bit steep, so you should do some extra shopping around. If the pricing appears to be pretty standard for your area, make sure the service you choose is licensed, experienced, reputable and backs their work with a guarantee in writing.

However, here are a few tips to help you insure you aren't getting burned on the repair:

First, check the model rating plate or sticker on the outdoor unit for information concerning how much refrigerant the unit holds. If refrigerant is needed, the amount required should not be more than about 10% over this specification. Also check the same plate for what the full load amperage draw should be for the compressor (may be shown as the FLA) to use as suggested below.

Next, put your system in cooling and let it run for about 10 minutes to stabilize its operation. Then, go take the temperature of the airflow into the return duct (at the filter will do) and from the supply duct closest to the indoor blower. The difference in the temperatures should be in the neighborhood of 18-25 degrees depending on the actual indoor temperature and humidity conditions at the time you take the temperature of the ducts. Finally, if you are able to, take an amperage reading for the compressor.

Low indoor temperature differences indicate their is a problem with either the refrigerant or airflow. When compared in conjunction with a low full load amperage reading for the compressor, it becomes an excellent indication the system has a lack of refrigerant and requires the attention of an EPA certified service person. Should your refrigerant be low, the leakage will need to be found and repaired before recharging the unit with refrigerant. Unfortunately, this can be quite costly but it does go with the territory.
 
  #7  
Old 04-19-03, 07:12 AM
PalmatBH
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I found a company that was more reasonable. They charge a flat fee for diagnosis and a flat fee for repairs based on the diagnosis. No open ended agreements. They came out today and determined that the charge was low and did a leak check in the outdoor unit. They found no leak in the outdoor unit. He then took a look at the indoor coil and connections and deduced that the problem was a leak in the indoor coil since the exterior unit had no leaks and the lines had no leaks the, leak must be in the coil. He is recommending that I replace the air handler unit at a price of $1650.00 total. That includes the air handler and labor to install it. He was unable to difinitively point to a leak in the coil but said based on his experience he is 99% sure that the leak was there. I can understand how dificult it would be to see a leak under all the fins on the coil but I would expect that their might be some symptom to point to the area on the coil where the leak is. Is it possible to find where the leak is on an interior coil? If so how do you do it?
 
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Old 04-19-03, 08:41 AM
firsthvac
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The use of a quality electronic leak detector usually will find the area for the leak source. As a last resort, we use an ultraviolet leak detecting dye unless their is a warranty involved as some manufacturer's will void the warranty with the use of dyes.

Did the technician indicate how low the refrigerant was and what the system capacity is?

Also, when was the last time the system had been serviced? It is possible that the leak rate is what is known as "acceptable" and not be in need of immediate repair. Though repairing the leak source is very much preferred, many times we find the unit has not been serviced for years and when the leak rate is calculated out, we discover the leak rate is well within normal allowed limitations. Unfortunately, if the leak is in the indoor coil, most times it will be unrepairable without a great deal of expense and changing the coil/air handler is a more reasonable option.

Depending on the size and location of the air handler, that estimate is not unreasonable. However, if you're system is over ten years old and you are going to be living there for another 5 years or so, you might just as well consider changing the outdoor unit too at the same time. The electric savings alone would be worth the cost of having a matched system. Just a thought to ponder.
 
  #9  
Old 04-19-03, 08:53 AM
PalmatBH
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The outdoor unit was installed in 94. It has never been serviced. The indoor unit is the original and is 23 years old. I replaced the motor on the fan about 5 years ago. What is the normal leak rate for this unit? Also, the contactor was charred, which I expect is normal, I checked it with a meter and it is working fine but the guy says it definately needs to be changed. Should it be changed and what is a reasonable price for that?.

I am considering replacing the whole system but I can not get pricing on the units I think would work. I have found the Carrier 38YRA024 outside unit and the Carrier 40FKB002 air handler. What are good prices for those?
 
  #10  
Old 04-19-03, 11:50 AM
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A/C

You say you like to play. Just put your amprobe on the wire to the outdoor unit. inside or out at the condenser cut off and read it .It will tell you if the compresor is running and look at the amp draw it can tell you if your low on freon also. But with frost on the line your low on freon. like firsthvac said Id gas it and see if it is just a long slow leak first. ED
 
  #11  
Old 04-19-03, 05:48 PM
hvacman
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a cool liguid line (small pipe) may be indicative of several things, and undercharged system is one.or a restriction of some kind in the small pipe will do that as well... did the heat work on the pump this past winter??? a smart solution, but it will cost you would be to have a qualified service person look at the system.
 
  #12  
Old 04-20-03, 05:31 AM
firsthvac
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You've definitely got your money's worth out of the air handler. Both components are old enough to warrant upgrading the system.

Are those the model numbers for the components currently installed for your home or for new components?

Also you didn't say how much refrigerant was needed?

I can't say if the contactor needs replacing without actually seeing it's physical condition, but if the points have indications of pitting a great deal and heavy charring, it should be replaced. The pricing for your area I couldn't say, but contactors in general can run from $25-50 (not including labor) for common sizes depending on manufacturer and type.
 
  #13  
Old 04-20-03, 07:23 AM
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sounds right

as stated you have gotten your money's worth from that ahu. a new one would be better matched to your outdoor unit and operate at a higher level, probably both efficiency and capacity, as well as reliability. that sounds like a good price for my area.
 
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Old 04-20-03, 08:29 AM
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Unhappy prices....

If I were you, I'd shoot craps.....charge the system if its low on gas. Our cost is about $1.70 /lb, mark up is most likely about $7.00/lb for R-22, Your labor rates must be union....We have a minimum of 1 hr, then 1/2 hr after that, first 1/2 to 3/4 hr travel one way..... some companys, as you stated, wack you the first hour, this is their travel included without having to get into a pissing contest about travel with the customer.... Most companies won't do residential because they nickel and dime you to death...Our mechanics gets an hourly rate (no commision), it keeps them honest.... no incentive to sell you a new unit, this means more difficult work than I care to do. (Generally lazy),... I have odds, as to it being a leak though, because you stated that the liquid line is cold......it sounds more like a restriction as someone stated earlier...since this is a heat pump, it may be a problem with the reversing valve, have you tried to put it back into heat and hear the gushing sound on the outdoor unit? If it hung up this might free it up..but only a temporary fix. If you have the bucks, change out both and get a quality SEER 14 unit, and get big rebates from the utility company to boot. Get several estimates though.
As to locating the leak...Spectroline has a dye that wont void warranties..have your HVAC company inject this dye capsule and charge it up. Next time they come back to charge it up because of the leak, let the tech know it has the dye in it, and to bring your ultraviolet light to locate it. The dye is about $50.00.
Talk to the service manager BEFORE he sends someone out, and tell him what you want, this should keep the time charge to a minimum, preferably the same tech...it goes quicker. This takes the guesswork out of where the leak is. These can sometimes be very difficult to locate, because they only leak under a high load or vibration ect....
 
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