A C Compressor Not Cycling Off

My A/C has suddenly stopped cooling. Given a 900 sq/ft. Experiments were done for a typical residential a/c system for run time fractions from 0. The compressor and fan controls can wear out, especially when the air conditioner turns on and off frequently, as is common when a system is oversized. Pressure is good, no leaks, air is ice cold. Fan speed setting is irrelevant. What else could it be? Could it be the clutch has gone bad? Any help would be appreciated. When a single-stage compressor starts, it produces a constant amount of heating or cooling until the compressor shuts off. When I'm driving and come to a stop light I feel cycling on and off. Even when the button that controls the fan speed is not pushed. Compressor not pumping internally 3. The a/c compressor should cycle on and off, the "freeze switch" in the hvac unit controls the cycling when the system is running. Now it runs constantly without clutch disengaging. I noticed my A/C compressor stays engaged when I turn the A/C on. “If the compressor is cycled off and on too quickly, an imbalance is created. See how to remove the compressor starting components to replace a 3-in-1. The A/C high-pressure cut-out switch and pressure cycling switch must also be closed. is low enough. Only blows warm air. Thus, there is no need to add any additional oil to your system. The owner also deserves a system that is the most reliable and the least costly to operate. When the low side is high, and the high side is low, the compressor is the not functioning properly, whether it is a CCOT (cycling clutch orifice tube), or a TXV (thermostatic expansion valve) system. The air is cold and works fine its just that the compressor is constatnly on and hurting my gas mileage and performance. This is a full explanation of how the system works. The problem is the A/C is running all the time. The pressure drop across the orifice tube is proportional to the pressure into the orifice tube. What Causes an HVAC Compressor to Burn Out & How Much Does it Cost to Replace? May 10, 2017 By [email protected] 6 sec on and about 6-8 off. The AC compressor does not cycle like would expect it to. This switch is connected to the suction side of the compressor and is actuated by pressure changes in the suction line. Jeep Cherokee 1997-2001: Why is the A/C Not Working? The air conditioning system in your Jeep Cherokee is quite advanced, but it doesn't have to be very complicated to find out what is wrong when it is malfunctioning. An air compressor is a specific type of gas compressor. The symptoms you mention seem to be similar. Your air conditioner's fan may remain on to circulate cool air to keep your home comfortable. Liquid Slugging is when the compressor tries to compress a liquid; liquid refrigerant, oil, or both; in the compressor’s cylinders. The SDL uses a Nippondenso 10P15c. It's normal for the compressor to not cycle on warm days - say anything much above 85 degrees. The low-pressure cutout switch is also known as a suction pressure control switch. Some cars cycle the compressor on and off to control flow and pressure of refrigerant. If that stops the cycling, the thermostat is the problem. As far as the AC compressor is concerned, it's either on, or off. Defective fan clutch or fan clutch. New 2012 Tacoma, 4x4 SR5 Double Cab. Now it keeps freezing up and the compressor won't shut off. It is commonly expressed in percentage format: Compressor on time ÷ (on time + off time) = Duty Cycle %. Since it's getting warmer we decided to drain the whole system and recharge it making sure we were at the proper levels and pressure. Cycling your AC compressor on and off like this unfortunately adds a lot of wear and tear. Once I turn it on the clutch stays engaged until I turn off the car. Go ahead and clean your condenser coils, replace or wash your filters and make sure the supply vents are clear of blockages. This imbalance will lead to a shortage of oil inside the compressor and bearing failure 1. Possibly the pressure switch may be defective. I got all the numbers off of the A/C compressor and no local parts place could find it listed anywhere. It has been 90 with high humidity so I turned it off for the night. It also causes it to. During the defrost cycle the BANK is protection against floodback. The fix is to bring the vehicle to the dealer to have the latest software installed into the vehicle. Marie Gauthier -- Wednesday, 14 August 2002, at 1:51 p. I took the car to a nearby dealership and they were not able to find a solution. A technician will test out the following parts to determine what to do when your HVAC compressor won't turn on: Capacitor; Start. Signs of a failing A/C pressure switch include your A/C being unable to cool your cabin, the compressor not turning on, or your A/C system cycling on and off faster than normal. Once I turn it on the clutch stays engaged until I turn off the car. it is mounted in the PDC (power distribution center) the location of the relay is discribed on the back of the cover. Usually I think first of an overheating motor. and even on the freeway it isnt cold by any means. it's not as simple as that.  Check the switch in the furnace or air handler, and the outdoor compressor. Also make sure no one has shut off the compressor’s 240-volt disconnect, typically in a metal box mounted near the compressor. You can turn off the A/C switch to stop the compressor, let it set for a about 10 seconds, turn switch back on, sounds fine, then after about 5 seconds, the rattling starts. My A/C compressor is cyclying on and off with an evenly distributed 6-second period (3 seconds on, 3 seconds off, repeat; estimated not timed). What do you all see?. It could be that your bearings inside the clutch have gone out though. I seem to remember that the system does blow cold air for a short time then nothing but hot air comes out. I tried the A/C diagnostic, but it didn't turn up any codes (it was just a steady blinking light). When you switch on the air conditioning, the capacitor supplies the required electricity for running the compressor and the A/C fan. * Compressor problem- Your a/c compressor is the engine of the refrigerant cycle. Choose top quality brands Denso, Four Seasons, GPD, Spectra Premium, UAC. If clutch engages, check wide-open throttle cut-out switch and A/C compressor cut-off switch. If the capacitor has failed it is a rather inexpensive repair. After taking my car to the dealer 3 times for this problem, the A/C compressor was replaced on 1/2/09; the sad part is that the new one makes just as much noise as the old one. You now just narrowed it down to either low refrigerant or a bad pressure switch. Defective thermostat or clutch cycling switch. This is a full explanation of how the system works. and it takes the humidity out of the cabin air when it cycles. The unit cooling the home quickly causes it to turn on and off rapidly (short cycle) since cooling is achieved quickly. A full cycle is determined by adding the compressor run time to its rest time. I would not do that with a $80 unit. If there's not enough pressure in the A/C system (indicates low refrigerant), the pressure switch will cut the compressor off until enough pressure builds back in the system for the compressor to cut on again, hence the cycling. All is good. com Bottom of Page. On a three phase system there are probably three capacitors, one for each phase. Liquid will be in the bottom. Okay i have checked all over this forum if i over looked a previous post i apologize in advance. With this Fujitsu C7. A compressor operating at lower output consumes less electricity. It will shut off by itself with excessive pressure or low pressures which mean two things - it's cold enough or low on charge. The unit cooling the home quickly causes it to turn on and off rapidly (short cycle) since cooling is achieved quickly. Grant it-Now i have ice cold A/C but from what i see, The comporessor doesnt cycle at all anymore. Only ran the truck yesterday, but, so far it hasn't frozen up. Louver outlet air flow decreases gradually, when blower is 'ON' and A/C is 'OFF', much drain water comes out Evaporator coil icing, thermistor is not cooled, or compressor clutch can be cut off when louver outlet air temp. com founder on our Forum or. From what we could figure out the only reason the compressor was cycling was because of overload switch. it is mounted in the PDC (power distribution center) the location of the relay is discribed on the back of the cover. * Compressor problem- Your a/c compressor is the engine of the refrigerant cycle. There is no "set" run time. Question: What is Duty Cycle? Answer: A compressor’s duty cycle determines the percentage of run time in a full cycle. If the clutch is not engaging, use a voltmeter to check for voltage getting to the compressor. Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. By the way, this is normal A/C system operation. The switch senses system pressure and rapidly cycles the compressor on and off when the refrigerant is low. compressor clutch cycling switch Low Low Poor cooling, hot receiver drier Expansion valve plugged, defective High Low Pressure guage readings are opposite of what they should be Air conditioning system will not turn on High Low Poor to no cooling system pressure equalizes very quickly when system is turned off Defective compressor or worn out. I hear my compressor turn on when I turn the A/C on, but that is all I hear. IMO and with some experience: Don't worry about a non cylcling compressor when you watch it at idle speeds. Now it runs constantly without clutch disengaging. old style ac compressors in cars were clutch cycling, but that is not what you have definitely not in a 2000 or later vehicle. The SDL uses a Nippondenso 10P15c. I can switch the climate control to heat, vent and even off but the compressor stays engaged. March 9, 2009 3:19 AM Subscribe. if my a/c turned off my car runs fine. You now just narrowed it down to either low refrigerant or a bad pressure switch. Start the engine and turn on the A/C. 5) compressor dying and i should drive car off of a cliff. It is the wierdest thing because I just let it run for like 20 minutes and the A/C worked great the entire time. By looking at the compressor, I see the clutch is not engaging. Checked the pressure with one of the freon filler hoses and it's dead center in the green. This causes the compressor to have to start while the refrigerant tubes have not had their pressure equalized. The on-off cycle should he minimal. After the desired temperature has been reached, the compressor can afford to rest a little and the on periods will be shorter. Again, most common reason for an A/C compressor not engaging is a lack of refrigerant (check that first). The job of the compressor is to move liquid refrigerant around in a pipe. Some cars run the compressor continually and use an expansion valve to control the flow and pressure of the refrigerant in the system. Ground compressor clutch circuit. is low enough. Run the engine with doors closed, windows up, and A/C on recirculate, low fan speed. Since the mid-1990s, most cars equipped with air conditioning have also been outfitted with electronic modules that tell your car’s AC compressor to cycle on and off. With our AC Cycling program, we send a wireless signal to a switch that we install on the side of your home or directly on the air conditioner's compressor panel. I am afraid its going to burn up my new compressor. Still no A/C. Verify good ground to pin T14/6 (brown/black). With a digital temp gauge in the center vent a reading of 42f is present and the freon gauge is reading about 28/240, this condition existed for 15 min. But I think this may be not the case. * Compressor problem- Your a/c compressor is the engine of the refrigerant cycle. K by gauge for tool to add canne. I don't believe the A/C compressors in my '93 Saturn and my '95 Saturn ever cycle off, regardless of ambient temp. Air Compressor Sprinter RV's & Conversions Talk. If there is voltage - the clutch may be bad. A refrigerator compressor is the center of the refrigeration cycle. this sensor is for frost control but is not cycling comp. The compressor pumps, or forces, the liquid from the. 2) A/C Clutch acting up. The clutch cycling switch cycles the compressor according to the pressure in the accumulator. I noticed my A/C compressor stays engaged when I turn the A/C on. If you rev it while idling, the compressor again cycles. An air compressor is a specific type of gas compressor. I just need to find out why Thank you all for the responses. A/C running constantly, does not shut off when set temp reached. But then, it started cycling off/on, and the gauge was near the max line, 50psi or so. You can use a R134a recharge kit to recharge your system if the A/C compressor is not working. This also happens when you go to defrost mode back to vent ( no a/c requested) the compressor will start cycling on and off and never stop. 0 liter, standard transmission So yea on really hot days my AC compressor cycles on and off continously. Because it functions in a continuous cycle on and off, it is subject to wear every time the AC is turned on. It turns compressor off when freon - pressure is low. All is good. [SOLVED] A/C compressor Cycling on/off. The A/C Compressor clutch cycles on and off constantly. bungalow with a 1. Dometic rooftop a/c compressor will not shut off. Compressor is old and i know its on its way out. It is the control that causes the compressor to go on or off as required for normal operation of the refrigeration plant. I want to take a guess for fun. With our AC Cycling program, we send a wireless signal to a switch that we install on the side of your home or directly on the air conditioner's compressor panel. When the engine is first started, The a/c will cool normally for about 5 minutes in "recirc" mode, probably twice that long on "fresh" intake mode. Question: Does a compressor that has 100% Duty Cycle mean that I can run the compressor all the time? Can I run my compressor 24 hours a day?. Still no cold air. The a/c compressor will cycle back and forth if the system. After that, it squeezes the gaseous refrigerant into a condenser. If it runs steady when the system is on could be low on charge or a stuck freeze switch, if it runs when the system is turned off it most likely a stuck relay in the pd box. An AC compressor cycling can be caused by just being low on R-134a. It's the low pressure switch. As in the case of the clutch, the compressor is usually not the culprit for the failure. 1 Year Warranty: We warrant all automotive parts provided by us to be free from defects in material and workmanship for a period of 1 year from date of purchase, when installed per our warranty policy. Sometimes it will stay cycled on for a little bit longer, but still no cold air. By looking at the compressor, I see the clutch is not engaging. There are also low pressure cut-out switches and engine overheat cut of switches. That’s normal operation when the AC or the defroster is on. Then, it started cycling on every 10, 15, 20 minutes, if at all. When your A/C is not working how long does it stay off before it comes back on? I have a 2005 2. The blower is working. Engine RPM (which changes compressor speed) is a contributing variable, too. its blowing plenty cold out of the vents and its cooling itself so well, it has to cycle off to keep from freezing up the compressor, even then that cycle on/off should be turning off a few seconds every minute or so. A/C now blows okay, but lately I noticed that the compressor is not cycling on and off. If your car has what's known as a CCOT (cycling clutch orifice tube) system the clutch is supposed to cycle off depending on cooling demand, usually around 21-23 psi depending on car make. If the cycles are very rapid the refrigerant level may be low, but the compressor is not designed to run full time when the AC is on. 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. Sounds like the bearing or clutches are gone in it. I've NEVER had a seconds problem with the AC. Some of these were used with the same arrangement as above using evaporator thermostat control but others used a pressure switch to cycle the compressor alternately off and on to obtain acceptable temperature control. Prevents compressor clutch from slipping due to low voltage. won't stay engaged 1 can of the stuff it still kept up the cycling (on for 2secs. The compressor clutch is controlled by several components: heater- A/C mode control switch,the low/high pressure cut off switch,the fin sensing cycling clutch switch, and the compressor clutch relay. It is the wierdest thing because I just let it run for like 20 minutes and the A/C worked great the entire time. Furthermore, the only visible working parts on the compressor are the electrical connections and the copper discharge and suction lines. The fan in the unit shuts off when the temperture at the thermostate is reached and the air coming out is cold. 97' VW Jetta, 4 cylinder, 2. This cycle of processes keeps the passenger compartment cool until the AC is turned off. We suggest every 15. Energy Savings. Electolux. Good luck, Keith _____. Nineteen eight-six through 1988 4-cylinder Fieros have a variable displacement, constant run A/C compressor. Actually there are good reasons for monitoring both low and high pressure when filling refrigerant, low pressure side may not be a good indicator of whether the system is full or not depending on the health of the system as a whole. [SOLVED] A/C compressor Cycling on/off. The blower is working. Because it functions in a continuous cycle on and off, it is subject to wear every time the AC is turned on. If a unit is left On the compressor will cool down and kick back On, going into a bad cycle of running for a short while, over heating and kicking off. Just to add the fan and A/C on/off switch works okay. From what you are stating it does not sound like it is a compressor problem but a sensor or wiring problem. If you're here, chances are you've tried to recharge your AC system and found a compressor clutch not engaging issue. If the power coming into the supply side of the switch is cycling on and off as well, then your problem is the supply power to the air compressor, not with the air compressor at all. If I have it on defrost/floor with the a/c light OFF, the compressor still runs as if the a/c light was on. Usually I think first of an overheating motor. My A/C system seems to have a intermittent issue such that the compressor cuts off after a few minutes and will not come back on until I leave it or the car off for some time. On for 15, off for 15 and so on. The Denso SES air conditioner compressor with variable crankcase suction valve technology is not. It's a very good little compressor, but it has two modes - on and off. Low airflow or dirty filter would cause freeze up of the coil after running for a while, not 5 seconds. The AC compressor is powered by your cars engine via a belt. Because corrosion of wire and terminals is also a problem in many systems, electrical connections and contacts should be checked during a professional service call. That's normal operation when the AC or the defroster is on. 4) A/C system actually freezing up. I do not see any DTC codes except a couple of irrelevant ones. 2) A/C Clutch acting up. What do you all see?. Can someone shed some light on this and tell me which switch it is?. If your AC won't turn off, you might not notice the irony of the situation right away. This information is the exclusive property of DENSO Corporation. Bearing maintenance shall not be required until 5,000 run hours. This would not only cause a refrigerant leak, but the oil could cause the compressor clutch to slip. Please note that the pulley itself will always spin while the center of the clutch may not. A scroll compressor uses an oscillating motion to compress the low-pressure vapor into high-pressure vapor. Overcharge system. 4) A/C system actually freezing up. Again, most common reason for an A/C compressor not engaging is a lack of refrigerant (check that first). These link to the most popular products in that category, and may not necessarily fit your compressor. The only time a R134a system should NOT be at 27PSI on the low side (or close to it) is if it is underworked, i. Defective thermostat or clutch cycling switch. refrigerant migration to the compressor during the off-cycle, all units have a pumpdown cycle. In other words, the ECU is not instructing the compressor to turn on. Download this information as pdf file; All DENSO A/C Compressors are delivered as complete assemblies, pre-filled with the correct type of compressor oil. 5 that is doing something very similar. old style ac compressors in cars were clutch cycling, but that is not what you have definitely not in a 2000 or later vehicle. A scroll compressor does not have any up-down motion like a reciprocating compressor. More often than not, the fan motor in the condenser outside has quit working properly. There are three large wires going into one terminal block on the side of the compressor normally. The holdback valve protects against overloading the compressor motor by regulating the inlet pressure to the compressor. The minimum value for this field is 0. I'm just trying to understand the physics behind why compressors in properly functioning and serviced systems cycle on and off. March 9, 2009 3:19 AM Subscribe. Had a bearing lock up on a friends last week and you couldn't even turn the motor over it locked up so tight. Some of these were used with the same arrangement as above using evaporator thermostat control but others used a pressure switch to cycle the compressor alternately off and on to obtain acceptable temperature control. New 2012 Tacoma, 4x4 SR5 Double Cab. The compressor is not cycling- it is on the entire time. In other words, the ECU is not instructing the compressor to turn on. Then, it started cycling on every 10, 15, 20 minutes, if at all. System has charge. The fan comes on, then the compressor kicks in as it should, but will shut off again in less than 10-15sec. it is a fail safe for those who don't run their AC in the summer to keep the compressor properly lubricated. data stream on evap tempt. There is no "set" run time. REFRIGERANT. the pressure tranducer is using a 5 volt supply, a signal and a ground, this is no go. I bought of can of R134a to recharge--it would only take a little in, but the gauge shows almost zero pressure on the low side. Fan speed setting is irrelevant. I think it might have been doing it before but I didn't notice it; now a fan turns on and off with the compressor so it's real noticeable. An oversized air conditioner will cool your home quickly but not reduce humidity and will short cycle. PROBLEM POSSIBLE CAUSES * Restriction in Receiver Drier or Liquid Line resulting in a starved. You can tell if your compressor is cycling on and off by looking at the clutch (or belt pulley) at the front of the compressor. Since I bought the car (from a private owner), the A/C has not given any indications of cooling. My air conditioner compressor cycles on and off constantly with outside temperatures between 45 and 75 degrees. The compressor will not cycle off when the A/C is on. (1 to 2 seconds on, 1 to 2 seconds off) is "short" cycling. Dometic rooftop a/c compressor will not shut off. By looking at the compressor, I see the clutch is not engaging. Louver outlet air flow decreases gradually, when blower is 'ON' and A/C is 'OFF', much drain water comes out Evaporator coil icing, thermistor is not cooled, or compressor clutch can be cut off when louver outlet air temp. Don't mess around with this yourself. COMPRESSOR FAILURES & CAUSES The following are the most frequent types of compressor failures. If I manually shut it off when driving, the difference is obvious so I am sure the clutch is still engaged the other times. After describing the problem to them and the possibility of needing a new compressor sooner or later, they just opted to get it fixed right now. Clutch stays engaged when turned on. '); } --> A/C COMPRESSOR KIT Kit contains a NEW compressor with clutch, receiver / drier, orifice tube, premium PAG oil, and o'ring kit. * Start delay, compressor lubrication cycle. Factory-direct at Power Equipment Direct. I was going to add some refrigerant, but that was before I checked all the other stuff. Wiki User 03/28/2011. The compressor pressurizes low-pressure vapor into high-pressure vapor, but it also causes the temperature of the gas to increase. Make sure this fits by entering your model number. If there's not enough pressure in the A/C system (indicates low refrigerant), the pressure switch will cut the compressor off until enough pressure builds back in the system for the compressor to cut on again, hence the cycling. Here is info that I can provide now: 1. If the compressor clutch is engaged and both pressure readings are the same, the compressor has failed. The fix is to bring the vehicle to the dealer to have the latest software installed into the vehicle. bungalow with a 1. 43KG of 134a and same result. The compressor began to cycle on and off, repeatedly. A/C works good but A/C compressor clutch will only disengage when system turned off. when commanded on the ac compressor should constantly run, if it clicks off it is because of a sensor indicating a problem. Factory-direct at Power Equipment Direct. My rooftop AC wants to cycle on and off unless I keep the thermostat at its coldest setting. Also, read the latest reviews for the First Air FAS4T 5-HP 53-Gallon Rotary Screw Air Compressor (460V 3-Phase 150PSI). Start the engine and turn on the A/C. The ac on my 2007 MKZ is cooling, but the compressor is cycling on and off about every 20 seconds--so it is not staying on long enough to cool the car adequately. I hear my compressor turn on when I turn the A/C on, but that is all I hear. Now it runs constantly without clutch disengaging. A/C now blows okay, but lately I noticed that the compressor is not cycling on and off. cycle off temp from evap sensor. Hex Auto Parts Common AC Compressor Problems Cool But Not Cold If the air conditioning is set to max cool and fans on high, but is only blowing moderately cool air: 1. If the power coming into the supply side of the switch is cycling on and off as well, then your problem is the supply power to the air compressor, not with the air compressor at all. Price: (as of - Details) Providing 200PSI and a 100% duty cycle, VIAIR's 480C Dual Performance Value Pack is an ideal air source solution for any air suspension kit, industrial application, air horns or off-road pneumatic needs. Re: A/C not engaging G'day add some more charge with the comp running until you see 2-220 on the high side and see what happens you may have a blocked TX valve though Oh and jumping the pressure switch will tell you if the rest of the elecs including the thermostat is working correctly as the comp should cycle on and off as it gets to temp. Disconnect it and cross the terminals with a wire or paper clip. I just had my heat pump replaced with a new 13-SEER 2 Ton York. The fan and all other funtions operate properly from the thermostat. So it comes on and stays on for 15 seconds then shuts off for 15. If the clutch is not engaging, use a voltmeter to check for voltage getting to the compressor. Yeah the dealership replaced one hydraulic line, the valve (the one nearest the engine) and evacuated and recharged it. My 1993 GMC pickup A/C compressor cycles erratically. If this is not done. I have found that when you start the van up with the atc unit on no a/c requested at this point and the compressor will start to cycle on and off this will never stop. Also try to notice if the belt is actually slipping over the pulley or not, or how easily the pulley. The condenser fan motor is needed to cool off the liquid Freon and the compressor in your condensing unit. If that stops the cycling, the thermostat is the problem. it hunts for an idle at first i thought it was a IACV but i cleaned my throttle body as well as my IACV that didnt help the problem i have noticed that compressor is. If there is voltage - the clutch may be bad. old style ac compressors in cars were clutch cycling, but that is not what you have definitely not in a 2000 or later vehicle. Earlier you said, 'M is a N. My air conditioner compressor cycles on and off constantly with outside temperatures between 45 and 75 degrees.  Check the switch in the furnace or air handler, and the outdoor compressor. Only blows warm air. [*]Did the compressor do what it was supposed to do expelling the refrigerant, or is something damaged?[*]Why is the compressor not cycling off like before?[*]Do I risk burning something up/further damage to other parts by running the A/C in its current state?[*]Is the compressor toast? Thanks in advance for any thoughts you can provide!. The fan stayed on throughout. your problem is most likely low refrigerant in the system, you need it charged. If I have it on defrost/floor with the a/c light OFF, the compressor still runs as if the a/c light was on. The A/C Compressor is not powering on but according to 2 dealerships compressor is working fine but its not receiving signal to power on. The cycling switch should turn the compressor clutch on at a low-side pressure of 43 psi, and turn it off at 25 psi. 3 liter diesel engine came in with the complaint that the a/c works sometimes. This is a 15 amp fuse and will be in position # 34 and labeled condenser/fan. 09, I had to install a lug kit on this compressor about 3 years ago, it burnt the terminals off the wires. Does it cycle at night, when there's no heat load from the sun?. Low airflow or dirty filter would cause freeze up of the coil after running for a while, not 5 seconds. Either your high side is going too high, or low side is going to low and tripping a pressure switch. The internal design of the compressors is not addressed here, because the design of the rest of the system is independent of the compressor details. The a/c system cycles to control low side pressure. The A/C system is controlled through the ECU. There is a temperature probe on your evaporator that controls compressor cycling. My central A/C unit compressor runs for 5-10 seconds then shuts off for 15-20. I tried disconnecting/ bypassing the A/C Clutch Cycling Switch to see if that would make any difference with no luck. When your A/C is not working how long does it stay off before it comes back on? I have a 2005 2. 00 + How do I check the overload? With it disconnected check it for continuity. Compressor not turning on. it was working fine until my wife took it in to have it sereviced and they added more R134a. The article above suggests common explanations for on-off or short-cycling of an A/C compressor unit. One of my chief complaints of 7th gen V6 is how quiet the engine is in contrast to how loud the A/C compressor is when it kicks on. With the engine off, remove the serpentine belt from the AC compressor, pull the fuse, and spin the compressor pulley by hand. In other words, cumulative A/C efficiency credits for an A/C system - from the A/C efficiency regulations and those granted via the off-cycle regulations - must comply with the stated limits. Moisture is what fogs up the windows. I checked the control knobs and they were in the off position. evaporator was not under any heat load and quickly reached the compressor cut off cycling point. When the engine is first started, The a/c will cool normally for about 5 minutes in "recirc" mode, probably twice that long on "fresh" intake mode.