Short on-off cycling of air conditioner or heat pump compressor/condenser unit diagnosis: What causes the A/C or heat pump fan condenser unit to keep cycling on and off rapidly and how do we fix it? Here we explain the common causes of compressor unit short cycling. This article series explains how to diagnose an air conditioner or heat pump that is not cooling: this article explains how to diagnose and correct air conditioning problems like lost or reduced air conditioner cooling capacity, reduced or no cool air flow, reduced or no actual lowering of the air temperature, or an air conditioner that won't start. Joe said: short cycling air conditioner compressor diagnosis: I have the same problem as Mathew: my A/C compressor cycles on and of every ~10 seconds. I is about 5yr old. What can we do to fix this system. Matthew said: short cycling air conditioner problems: Our air conditioning compressor cycles on and of every few seconds or minutes. What can we do to fix this systems not even a year old

This was an interesting article. My central AC works perfectly during the night, but short cycles 5 seconds on, half second off on hot days. Any thoughts as to what would be causing this? 2016/09/12 Linda Jackson said: Our Trane Ac unit keeps cycling on and off about every 10 seconds. York 3 ton heat pump. Heatpump kick on and right back off? Super heat is perfect!! I'm lost plz help! Unit is jumped and and cools great great pressures, but kicks off as soon as it kicks in when wired properly? (mod) said to Joe and Matthew, Mike, Linda and others (re questions just above): An air conditioner or heat pump that is cycling off and immediately back on or cycling off/on every 10 seconds is abnormal and is likely to damage the equipment. I would turn the system OFF while waiting for repair, as I worry that more components will be damaged. I suspect this is a control board or relay problem, possibly related to operating temperature or pressure but that's as far as I can get.

Short-cycling on and off of an A/C compressor unit every few minutes (say 1-5 minutes) sounds to me like a diagnosis and repair are needed. A second sort of "short cycling" of the compressor also suggests that diagnosis and repair are needed: if an air conditioner or heat pump compressor runs for a very long time (i.e. the cooling system is not able to reach the indoor set point on the thermostat) and the the compressor shuts off for just a few minutes, then re-starts, I suspect trouble. diy portable ac unitCauses include lost refrigerant, ice-blocked cooling coils, thermostat not working properly (blocked, in sun, in airflow, dust-crud clogged).window ac unit ratings But if someone is turning the system on and off quickly, the compressor may have a hard time re-starting against the pressure on its outlet side. ac units for low income

A starter capacitor addition or replacement might fix the problem. If your A/C compressor is showing this symptom but works OK if you leave it shut off for 30 minutes or longer, that may be the trouble. We have also see or a damaged compressor internal refrigerant valve causing high head pressures; In sum, you need a service call from a professional to correctly diagnose and repair the problem. Ask the service tech what she/he found and let us know - what you find will help other readers. Overall: I'd like to see a compressor/condenser unit ON cycle time of 10-20 minutes. The length of time before the next ON cycle of the compressor/condenser unit isn't standard but it ought to be more than 5 minutes, perhaps 10 or more. The rate of heat gain, air leakage and other factors determine how quickly a cooled space heats-up again once the cool air flow stops. If an A/C or heat pump compressor/condenser unit is on about half-time and is cycling on/off say 3 times in an hour in hot weather while cooling a residential building with typical insulation, air leakage rate, and heat gain rates for its climate, that's probably normal.

In very hot weather an air conditioner or heat pump system may run continuously or nearly continuously as long as the indoor thermostat is calling for cooling. It's possible for a residential air conditioning system to be operating normally when a compressor shuts off, then turns back on depending on the system's controls. That's so if the "off" period is long - perhaps 10-15 minutes depending on weather conditions and system capacity. In moderate heat, 10 minutes on and 10 minutes off would not be abnormal but in my OPINION it's close to the edge. A compressor motor that is cycling on and off rapidly is going to be damaged by that condition and depending on the system design, it may also ultimately have trouble re-starting against high head pressure in the system. I think most HVAC techs (more expert than I) will agree that if we get down to 5 minutes or less on and off there is definitely a serious operating problem to be found and fixed. In any event, 5 Minute on-off cycling or more rapid on-off cycling of an air conditioner or heat pump is very likely an indicator of trouble.

The article above suggests common explanations for on-off or short-cycling of an A/C compressor unit. Usually I think first of an overheating motor. That in turn can be due to a motor that's failing or to another cause such as low voltage; a bad control board or contactor are less-likely candidates but then your onsite tech may find something else. If your air conditioner or heat pump has the opposite problem, staying on too long, see LONG-ON CYCLING AC COMPRESSOR. Continue reading at COMPRESSOR / CONDENSER DIAGNOSTICS or select a topic from the More Reading links or topic ARTICLE INDEX shown below. Or see REPAIR GUIDES A/C / HEAT PUMP 300 posts, read 688,560 times 284 posts, read 1,119,417 times 3,702 posts, read 13,835,465 times 20,793 posts, read 43,207,769 times 14,718 posts, read 15,190,421 times 13,664 posts, read 13,229,960 times Originally Posted by NeilVA I'd have to disagree with that assessment as a low charge would likely result in long run times.