This could also be a fan motor problem where the motor bearings are getting tight and the fan motor is over-heating. Hi Ms. Avon! Looking forward to a career in HVAC? Steve. You can hook the low pressure switch back up after you get the system fully charged. Hi Charles! No issues but when I installed a new Sensi thermostat when I turn the a/c breakers off the heat doesn’t work. All good. Your problem sounds like you have an air conditioner that is either over-charged or you have a restriction in the refrigeration system that is causing it to go off on high head pressure. I am sure that when you figure out what they did with the wiring that you will like the Sensi thermostat as well. “Nothing is more valuable than helping another person succeed!”, We would love to help you troubleshoot and repair your furnace or air conditioner problem! The low voltage transformer on your furnace should be directly connected to the control board through the R and C (com) terminals. Fan off; Burner on; Fan on; Burner off; Pilot on; Fan off; etc. If your utility company is cycling your AC off and on every 15 minutes then this seems like it would be going against what they are trying to accomplish which is reduce the load on electrical usage and to reduce the strain on the utility company’s equipment. My daughter just called to tell me that after she turned on the furnace she smelled something coming from the vents. I personally would always want an OEM compressor made by the manufacturer. You could also try disconnecting the Y wire from the thermostat and see if the unit outside stills runs. Steve. I have a 94% Bryant furnace and I like to keep an ignitor, flame sensor, control board and draft inducer on hand. Appreciate the quick response too! I’m skeptical because it seems even if the outside unit could not run, why would that prevent the furnace & thermostat from receiving any power? Or would you suspect something else? Become a part of our community of millions and ask any question that you do not find in our HVAC Q&A library. I would suggest testing to make sure the “G” connection (24 volts between the G and C com) on the thermostat is being energized when in emergency heat. Sounds like you either someone wired the system wrong, some thermostat wires are shorted out and causing the outdoor unit to come on or you have a heat pump unit where as I am sure you already know that heat pump units run in the winter time. Read them carefully before applying for HVAC engineer job. I don’t smell gas. Write. It’s a split system and I noticed the R22 was let out somewhere near the bottom of the compressor. It will sometimes take 10 minutes or 30 mins or an hour to kick back on. I just need to be pointed in the right direction. I have a Carrier unit about 8 yrs old. This is what causes the fan relay on the control board to close and runs the fan in the cooling mode. When it was working for short periods I found the defrost heater control switch would fail open and it would go into “cool down mode”. It sounds a little simplistic, but good power in, the fuse is good and bad power out. If it does run then you do not have a thermostat problem, but some shorted thermostat wires or another control that is causing this problem. If you tie all these wires together and nothing works then sounds like an electrical problem (maybe thermostat wires) or yes, it could be the control board. If you aren’t getting voltage to any of the heating elements then trace back to see where the voltage stops and this should point you to the problem. Steve, I have an electric AC and propane heater combo why does my AC come on and off all the time like it’s trying to run propane. as a result the furnace does not work and the central air is also affected. Many times when this happens homeowners of heat pumps will hear loud noises and see hot smoke from the melting of the ice coming off their outdoor units. You should not have any resistance between any two wire once they have been disconnected. Heat Transfer Quiz Questions ; Ozone Layer Depletion Quiz ... Condenser Basics Quiz Questions; Boiler Basics Quiz; HVAC Heating Basics Test 1; HVAC Heating Basics Test 2; Cooling Towers Quiz Questions; Cooling Towers Quiz Questions 2; I noticed that when i turned breaker back on one of the two heating coils under the fan comes on and stays on for a minute then clicks off, even while in A.C. mode. Steve. Hi Mr. Taylor! This can be dangerous since you are working with live electricity high voltage. Answer: Willis Carrier invented the initial air conditioner prototype in 1902. We cleaned the evaperator on the inside of the outside unit it was dirty but that was not the problem it is still pulling the low side down to zero and cutting the unit off…, Hi Mr. Brown! If you would like for me to look up any parts then please send me your furnace’s model number. I try to discuss this problem on the following page: https://arnoldservice.com/problem-fan-will-not-come-position-fan-will-not-come-turn-thermostat/ Since your fan is running at low speed some of the time I would suggest that you check the thermostat to make sure you are getting 24 to 28 volts AC between the G (green) and C (com) terminals when the thermostat is calling cooling. This is a manufacturer’s warning and quite honestly not many people abide or pay attention to it. Steve Arnold, I have a issue with the a ac unit the unit starts the motor doesn’t I change the motor but it still doesn’t come on, Hi Olivia! Browse from thousands of HVAC questions and answers (Q&A). If you are not getting 24 volts between R & C then you must have a transformer problem or a blown low voltage fuse on the board. I hope this solves your problem. Many times they will connect the yellow wire with a wire nut inside the air handler. Most of the time the problem is in the thermostat wires where sunlight, animals and wear have deteriorated the insulation on the wires and they are shorted together. This most certainly sounds like an air flow problem or a problem where the company did not install a large enough units. Steve. I think it is because my furnace … One of my suppliers said there was a recall on the TXV valves and after replacing the valve the manufacture was recommending the AC Renew product to prevent it from happening again. So in order to run the 1.34 horsepower pump you would need 556 square feet of solar collectors. No change in cycle. HVAC Test Questions. You or I would have to study the unit’s wiring skematic to get an idea of what the sequencers purposes are in your system. B. Hello, I have a question about buying a two stage Carrier Air Conditioner along with coil to use with an existing single stage furnace & blower and will the two stages work in the A/C but only blow at the one speed? If I leave the system on, in about three or four minutes the compressor starts back up, but the fan stays off. Please make sure that you are getting 210 to 245 volts to the motor when the contactor closes and when the unit is calling for cooling. Use these flashcards & quizzes to ace any certification exam. I hope you can get this company to take care of your problems. Flipping breakers doesn’t bring it back to life. It isn’t every 15 minutes. Hi Rich! If the contactor is not getting the needed 24 volts then this can cause the contacts to chatter and burn up quick! Hi! If I allow my electric utility company to cycle my home a.c. every 15 mins. I have looked around and read that reputable companies will not install an R22 unit, so in due time I will fork the money for a new system. What is going on? It is very hard on the compressor to run without enough refrigerate because a low on charge system will allow the compressor to over-heat, melt the compressor motor windings and burn the compressor up over time. Our Carrier parts program shows a compressor part number SRD480HC scroll compressor. Comment. You will need to wire past the low pressure safety switch in order to charge the unit. The warning is there to prevent the compressor from possible valve damage that could occur if any liquid refrigerant has migrated, and is sitting inside the compressor. Sorry for your trouble! If the air coming out of the vents is not cool I would suggest hooking up gauges to the unit and see if the compressor is pumping or not. The heat strips come on but not the blower. Test with a volt meter set to volts AC. Or do you know of any other options? The fan comes on; 30 seconds later the pilot light comes on; 30 seconds later the fan goes off; 6 seconds later the burner comes on; 65 seconds later the fan comes on; 1:30 seconds later the burner goes off; 1:20 seconds later the pilot light comes on again; this then repeats. After about 10-15 minutes, (well before the thermostat reaches the target temp setting), the compressor fan turns off… the compressor stays running… the pressure builds to about 650psi in about 30 seconds… and then the compressor turns off. I hope you can easily find and fix the problem. My guess is that the coolant is not equalizing quickly enough, and I don’t have gauges to confirm this. I am terribly sorry to hear that your AC is not working right. Thanks Steve!!! Check to see if the blower wheel spins freely. Like I stated, wires are all good no cuts, no breaks. Steve, Thank you very kindly for your timely response which is very rare no a days. Steve, Replace expansion valve on evaporator vacumn unit started charging unit had 150 on suction line turned unit on pressure dropped to 20 suction line frosted up unit shut off unit won’t run long enough to charge 410-a system, Hi Mr. Vuorela! Great Question! so I thought they may have blown the board. Steve. You might have too large of an air conditioner in your home. Only messes up during the day when its hot and sunny outside. More than likely over time the evaporator coil will freeze like a block of ice, impede the air flow and could slug out the compressor. Could the fan cage just be dirty? I am sorry, but I do not know anything about the Riello 50 f5 you are have installed. This is a link to a great book for servicing and charging air conditioning systems. Please get this fixed as soon as possible because like I say this is very hard on the compressor and your AC refrigeration system. The Honeywell shows heat on all the time. Test between the G and C (com) terminals you should have 24 to 28 volts AC between these two terminals. I also checked for continuity on the 5 limit control switches and they seemed good. Hi Jaron! I went ahead and used the gas valve and it seems to work fine as I can hear the puff of gas before the blower kicks in. Those wires then tie into the defrost control board. Wondered if this sounds right to you too? Air Conditioning and Heat Pump Troubleshooting Simplified, Air Conditioning & Heat Pump troubleshooting questions with answers index, Furnace troubleshooting questions with answers index, Gas & Electric Furnace Troubleshooting Simplified. Everything works normal until I turn on the emergency heat. Home; HVAC Basics. They recommend waiting three hours to make sure all the liquid refrigerant is boiled off. Constant Air Volume (CAV) is a type of heating, ventilating, and … Thanks for asking these important questions. I have a Sensi Wi-Fi thermostat and love it. I would make sure that your thermostat wires that go out to the unit are in good shape and not broken or shorted out. Please send me the furnace model number at our email address: What is the difference between EXPXXFIL0020 and. I had disconnected the R and the C from the thermostat terminals and checked between them when I saw the 4 volts. Thanks for taking time to create these quizzes. Best of luck in finding and fixing the problem. Is there something I might check without having HVAC exp.? So…if the unit does not run, is there refrigerant to be removed or can we simply take the unit apart? Of course I checked the transformer at the connector that plugs in to the board. In refrigerator which of the following is compressed: The absolute pressure of a gas at constant temperature varies _______ as its volume: _____ is an instrument used to measure relative humidity. Between red and black would be 220 to 245 volts and between red to white and black to white would be 120 volts. Here’s what I found out. Problem 2. If not you might have a low voltage transformer that is out or a blown fuse. Do I have a bad defrost control board? Steve. On the Thermostat side I have the following: C Blue O White Rh Red Rc Jumpered to Rh Y1 Yellow G Green W1 Jumpered to Y1. Most of the time when an AC short cycles it is caused by an AC system that is sized too big for the home. Use our online practice test to help you study for the general knowledge HVAC certification exams. This sounds like a thermostat problem or some thermostat wires that could be shorting out and causing the unit to start on its own. I hope you can easily find and fix the problem. (6) O (orange) goes to the reversing valve on the out door unit. Steve. Sorry to disappoint you. I would suggest making sure all connections to the board are good and tight. I just can’t imagine using wood instead of concrete block. The mass flow rate of water to the cooling tower is 590 gpm Solution for HVAC Question #2. Please make sure if your thermostat has batteries that the batteries are good. Thank you for any help! can I jump the sequencer to test it,? Steve. I live in Southwest Missouri and for the most part our winters are fairly mild. I’m from Portland OR where the humidity is fairly high in the winter…, Bryant Carrier 3 Wire Pilot Burner Problem Resolved. If the installer installed a blower that is too large for the duct work that you have then this will be noisy. I also noticed after turning on the AC that after the cooling cycle is over and the compressor shuts off the blower continues to run for a minute or so…like the heater should do after the heating cycle is complete. Therefore, what else could have been compromised on the unit and could there be other integrity issues to consider on my 11 year old HVAC unit. With this small of a motor I would not think that you could have more than a 2 ton air conditioner installed with this furnace. The duct work inspected by two companies which both said it was fine. There is a hole next to the vent screw that an adapter screws into and the flex tube fits into the adapter, the other end goes into the pressure switch. Starting AC equipment is hard on the system because it jumps the amperage/electrical usage up each time when AC equipment starts. If this problem just started then I would think that this problem sounds like you either have a thermostat problem or you have a short in your thermostat wires or control (control board, sequencer, relay) in your furnace. I would suggest checking your low voltage at the control board. What Is Air Conditioners? We have a troubleshooting flow chart that I hope will help you out on the following page: https://arnoldservice.com/furnace-trouble-shooting-flow-chart/ I hope you can easily find and fix the problem. What do you recommend in order to find the source of power if it may be hidden somewhere behind existing structures… we are not in a position to pay an arm and a leg for someone to come by and get into an involved project if it’s not necessary. My question is I replaced the PCB in my air handler because it was burnt up. If I leave the system on it just continues this cycle. Steve, I recently had my HVAC unit replaced. Thank you so very much for telling us how you solved the problem! I can hear The compressor running one minute and then it just shuts off. Was ready to buy a new gas valve but decided to give the whole log set a good cleaning so out it came . What could be the problem? everything is now NEW.. still no low voltage to outside… noticed that one of the wires on the double stack sequencer was a little dark, the thermostat still is working, fan cycles on heat, cool, and emergency, elements are heating, just still no compressor, or heat pump.. could a sequencer be my problem?? Steve. Every person (all professionals) told me “Your problem is a direct result of their install. I have a Rheem RBHP-24J18S air handler that has me pulling my hair out. Sorry to hear that you are having this problem with fitting the air handler into your attic. thanks. I would suggest that you test between the yellow wire and C (com) with a meter set to “volts AC” with the thermostat calling for heating or cooling. Most fuses as you probably know are rated by amps. I’ve checked the breakers, the float valve, and everything seems fine. If you hear your contactor chatter then please find out what is causing the low voltage problem soon, because this chatter will cause a contactor to fail soon. I hope you can easily find and fix the problem. I checked both sides the transformer and getting 24V and 240V and getting 24V going to the control board. I would suggest turning off the power to the furnace and check the blower wheel with a mirror to make sure it is clean and there is nothing stuck in the wheel. This could also be caused by a filter that is too restrictive. Could I go ahead and use the gas valve without the flex hose or should I scrounge the internet for my original gas valve? The system supplies chilled water to a college campus with multiple buildings. No attic fan in the attic. If it is real hot then you need to call someone to find out what the problem is before it burns the compressor up. It made no difference. I hope someone will see your question and advise. I think I’m going to call in a professional at this point for some diagnosis. Hi Robert! Thanks, Steve. We discuss this problem on the following page: https://arnoldservice.com/problem-furnace-air-conditioner-heat-pump-will-not-come-on/ I hope you can easily find and fix this problem. I would start with the float switch, the door switch on the furnace blower door, the air handler or furnace control board testing between R and C (should have 24 to 28 volts AC). Thanks for the great question! (3) Y (yellow) wire going to the contactor of the outdoor heat pump unit. The wire shielding on these wires had worn away (Heat?/Vibration? Once he found a blown fuse, the last time this happened the fuse was good and he could not find the problem, do you have any suggestions what could cause this, thank you in advance? Thoughts? Your new unit should be under warranty for both parts and labor. I got a Carrier HVAC outside unit that keep burning the contactor It was working fine then, start switching off and on. A weak capacitor will also cause a fan motor to stop. A weak capacitor will cause a motor to not run. It looked like the blower kicking in was stealing enough of the pilot flame away from the strike heat sensing plate to cause it to cut in and out. Steve. Read: How to become an HVAC technician Who is the inventor of the modern air conditioner? Steve. I have some troubleshooting tips on the following page: I would start with testing the thermostat to make sure it is getting a constant 24 to 28 volts between the W and C (com) wires when calling for heat. Hi Jaron! If you have a unit that is a heat pump with gas as an auxiliary heat source then when a heat pump goes into defrost mode the outdoor fan will stop, the reversing valve will shift into cooling mode, auxiliary heat will come on and the ice which has accumulated on the outdoor coil will be melted off. This customer had installed a new 3 wire pilot burner, then decided to clean the old 3 wire pilot burner to see if he could get it working. I began to think it was the thermostat, but one repairmen claimed my thermostat is fine. I am sorry that I do not know the answer to your questions. They are probably concerned over their health and would rather come back in the morning when the attic is cooler. A compressor hard start booster might help this situation. Click here: Troubleshooting Heating Problems, Propane furnace not working when temperature got down below freezing. Sometimes I’ve noticed air coming out of registers as 65+ and not consistent through all vents. This sounds like the fan is cutting off during the cooling cycle which causes the unit to run high head pressure. Best of luck in finding and fixing the problem. Hi Steve, so my transformer is working correctly, I get 24 volts to the thermostat and also get 24 volts coming outside when I check the wires with my volt meter. We discuss this problem on the following page: https://arnoldservice.com/problem-your-fan-on-your-furnace-runs-all-the-time-and-will-not-shut-off/ I hope this helps you find and fix the problem. With temps during the day normally above freezing and dropping below at night. Hi Jerry! It has started short cycling. I paid one of them to change the transformer on the furnace to 24 volt. The air flow through the duct work will be noisy if the duct work is too small. recently I had AT&T installed AT&T digital life system. Steve, I have a hot water coil on my return side of my air handler unit that I use when burning wood. I would suggest turning the power off to the unit when it shuts down and lightly touch the top of the compressor. I hope I have answered your question. Tech did not have any idea what was causing the vibration. Listed below, are frequently asked questions related to Heating, Ventilation, and Air Conditioning. We bought a house last August and the air conditioning was working fine, though the unit is about 10 years old. Thanks again! Sorry, this can be time consuming. I hope you can easily find the problem. You might have a short to ground in one of your low voltage controls or thermostat wires. Sometimes the relays are contained in the electric heater product or model number. please, check if you have a condensate overflow switch on the unit. Yes, you are correct, in order to get the cool refrigerant gas coming back to the compressor from and evaporator on the 2nd floor, they might of had to over-charge the unit thus making the compressor have a hard time starting. First noticed the R22 was let out somewhere near the bottom of the.... This hot day a limit that is out or a loose connection at Angie s. Time is because the outside electrical box the reviews and see how you! To follow-up…figured out the problem in either the motor or capacitor this post wires…put the white on the exchanger... What size air conditioner that was installed what refrigerant the unit when it shuts down your AC refrigeration system furnace! 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