Carrier Condensing Unit clicks in HEAT mode / defrost problem
Hello. I have a Carrier "heat pump style" A/C. (Not sure of the exact model at this second because I am working on the base at the moment.)
The unit came with the house that we bought back in 2001. I got back from Iraq near the end of the winter season last year and noticed that my condensing unit was making a repetetive clicking noise. My wife and I live in eastern NC, so the temperatures seldom drop too much below freezing.
In the Cooling mode, the condensing unit does NOT click, so I did not realize the problem still existed until recently. The unit makes a continuous "clicking" noise, about every 2 seconds while running in heat mode. The unit continues to heat our house, and eventually the clicking stops (after 1-2 hours). Lately the unit has been freezing up. Mostly when it gets really cold outside. I know that a low coolent level will cause this, but early this spring I had the unit serviced with coolent and they did a complete check for leaks in the system. The serviceman found a leak and repaired it, charged the system and then charged me and arm and half a leg.
I do NOT think it is a low coolent problem, however could be wrong. When we first turn on the unit, it runs fine and will go into the defrost mode like it was designed to do. Steam does in fact defrost the entire unit. However, the unit stops defrosting after a couple of cycles and it freezes up again.
Could this be a thermostat or thermister problem? I do not want to let this keep happening and end up overheating or frying the condensor unit.
Obviously I do not have the money at this time to call another repairman, or he would have already been here to fix. I hate calling a repairman to fix something, charge me $75 just to pull into my driveway, look at what is broken, and tell me it was something I could have fixed myself.
I have gotten a lot of help from this site in the past with other issues, and have gotten great responses that have worked.. but most importantly.. worked the FIRST time.
Please help. Thanks in advance.
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Re: Carrier Condensing Unit clicks in HEAT mode / defrost...
Replace the thermostat on your Heat pump, get the model number and search the net for a distributer. If that doesn't fix it, you'll have to call another serv tech, it could be that your defrost board is acting up.. Let me know for my info also, I'm curious as to what they find. Also, being a Contractor, I don't charge just to come out, I usually diagnose then tell the homeowner. Find a Contractor that will do this for you, if it's simple to fix yourself, he should only charge you partial serv call..
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check the thermostat also check the inline fuse for the electric heat coil . check wires in control panel they tend to burn and last check to make sure reversing valve is changing over located by the compressor
Well...they are kinda the same. The condenser is where the refrigerant is condensed from a gas to a liquid. When in AC mode this happens outside at the AC unit. (You ever put your hand over a running AC unit in the summer? Feels warm!). When in Heat Pump mode the process is reversed. Instead of condensing the gas to liquid outside (which creates heat) the condensing happens inside and helps warm the building up (with the help of the fan of course). So essential the condenser is where the gas is condensed into a liquid, which creates heat. A heat pump can reverse the direction of the flow and cause this condensing to happen either outside or inside.
This is a very watered down version of what happens but I hope this is sufficient for what you are asking.
HFC-134a ? Critical pressure is 588.9 a . With a 93 LL temp and 575 head, I would suspect 1. Air in system or 2. Ref. has gone critical. With a 110 psig suction/85 deg.F and a LL temp of 93 deg.F/125 psig
Rather lengthy but here it is.
The outside unit(heat pump) has a reversing valve, a defrost board, a crankcase heater, a metering device(txv or piston) and an accumulator. This is what makes it a heat pump instead of a straight air condensing unit.
When in the heat mode the outside unit becomes the evaporator and the inside unit becomes the condensing unit.Before somebody corrects me i am just stating what is different in a heat pump.
When the system goes into defrost several things happen. First the system has to call for a defrost cycle. This happens on a time and temperature sequence. When the defrost board times out for a defrost check(the defrost board has a jumper pin to determine how long before the system will check for a temperature(thermal switch) is open or closed. This switch is in the normally open position. It will close at 35 degrees(depends on the switch). This switch is located on the copper line in the condensing unit. If this switch is closed then the system will go into defrost. Now for the good part. This will shut down the outside fan, switch the reversing valve, and the outside unit will essentially go into cool mode. Because the fan is off the compressor will heat up very rapidly and the refrigerant passing thru the coils will be hot as well. This will cause the ice buildup on the outside unit to melt(defrost). This will continue until a temperature is met or it times out. Then the system will return to the heat cycle. One other thing, depending on how your system is wired the inside unit will turn on the auxillary heat while the defrost cycle is in process. That way you will still have heat while the defrost cycle is in process.
It is not uncommon for steam to come out of your outside unit while this is going on. It can also be quiet noisey sometimes.
Hope this explains what you wanted to know. If not just reply to this with any other question you have about the cycle.
Hello,Your heat pump is in DEFROST mode and this is normal(only during a call for heat).When in defrost mode the supply air temp should still be warm as 1st stage electric heat strip comes on during the cycle.If the unit did not defrost every once in a while the outside unit would look like a snowman after a while.The reversing valve is the "bang" when it changes over.
The refrigerant and compressor are related in cooling the room.As for heating problem the thermostat needs to be checked.
if you're used to a certain temperature of air and your heat pump is producing much cooler air, take the following steps. (Note that a heat pump may go into a defrost mode to prevent icing. When this happens, it can temporarily output cold air. Also be aware that the heat pump will have to work harder to produce heat.)
1) First be sure the thermostat is set properly. Try raising the set temperature 5 degrees F. and waiting a few minutes.
2) Be sure the room-heating registers are open.
3) Check the heat pump filter. If it's dirty, change it.
4) Be sure the auxiliary heating elements are working .
5) Clean the coils of the outdoor condensing unit. If still the same problem then thermostat needs to be checked and replaced. Thanks.
Assuming we are talking about a Heat Pump system with an outdoor condensing unit and an indoor air handler, it is not uncommon for electric bills to escalate during the harder winter months.
Typically, the auxilary heat light energizes whenever the electric strip heaters are in use. These heaters are used to supplement the heat from your heat pump system which will be unable to maintain desired occupied setpoint with outdoor temperatures below 35degF. At outdoor temperatures below 35degF is not uncommon for the heat pump to run non-stop and the electric heaters will cycle on and off as the temp in the house drops between 1/2 to 1 1/2degF below setpoint. The electric heaters will also come on when the system goes into a defrost mode...defrost modes typically last anywhere between 2 - 8 minutes. The emergency lights, depending on your thermostat, will come on whenever the thermostat is placed in EMER HT. Some systems energize the emergency heat lights to indicate there is a problem with your condensor unit.
I suggest you ensure the thermostat is in HEAT mode and not EMER HT mode. Also, while the system is running, step outside and visually inspect your condensing unit. Is it running? Does it appear and sound like it is running normally?
Don't forget your air filter. This is the single most important and most-neglected maintenance item on your system.
If after these steps, you still feel as though you are having problems and would like to try and correct them yourself, please let us know.
I hope you find this information helpful. Good Luck to you! :-)
The outside fan may run if the unit is in defrost mode this is normal for most heat pumps it is there way of trying to keep the outside unit from staying iced over so the next time the unit runs it will have air flow through the coil and the ice will not be there to prevent air flow.
Look for any refrigerant leaks - no or low refrigerant can cause problems in both modes. The unit may be going off on low suction.
The unit may be stuck in the heating mode.
Make sure the system is calling for the correct mode (cooling or heating) - some systems are auto, but if you can, select cooling since that is the requested mode. Check for power at the reversing valve inside the condensing unit. If power exists, then the reversing valve is stuck. It could also be the reversing valve solenoid coil, so make sure that isn't bad. There should be a strong magnetic field at the solenoid coil.
If you can hear the reversing valve clicking (moving), check the T-stat and make sure it will switch modes. Also check the reversing valve relay (those can be located in either the indoor unit or condensing unit).