Ac Compressor Clutch Turns On And Off

Like I said first take it off and start up the rig and see if the ac cones on if so then its not the controls enough the compressor clutch is still engaged. A/C compressor clutch not engaging switch rigged up to directly turn the compressor on, just to make sure everything works, and I'm having no problems with any. After compressor installation, turn the compressor shaft a minimum of 10 revolutions to remove excess lubricant from the compressor. The AirCon can switch itself on and off intermitantly when you have a faulty resistor pack/thermostat, faulty track on your Accelerator position switch, faulty Hot-Cold control, faulty system pressure switches, compressor clutch, or associated relays and wiring. Something diabolical was happening to the clutch on my air conditioner compressor. If it still has 12v then the clutch coil is bad and the circuit is opening as the coil warms up from being on. The AC compressor will normally cycle on and off while it's in use, depending on the demand for cool air. While this may seem like a death sentence—especially in the height of summer—replacing AC compressors isn't the most complicated task. On these settings, compressors turns on and off every 10 seconds approximately. If #3 is the case, try manually engaging the clutch. Ford How to: Fix Air Conditioning Clutch (Air Gap) - YouTube You can also check to see if the voltage on the coil wire is turning on and off too,just remove the connector again an start the engine,turn on the A/C,and check to see if the voltage to the coil is steady,if the A/C compressor is switching on & off,it could be a bad pressure switch. Both the pulley and the clutch should be spinning. (vehicle, sensor, clutch, 2004) on either the compressor clutch or the pressure switch loose. If it is not, check if the power wire to the compressor clutch is getting power. The Auto Air Conditioner Controller puts another switch in after that, one that turns off the compressor at high throttle angles. Is that because it can't fill if the compressor doesn't kick on?. Cycling is part of the normal process through which your HVAC operates. power to activate the relay). In those cases, you would require an immediate change service of the same. Ok I'm fully aware that most if not all cars turn on the AC compressor when you switch the hvac controls to defrost. 1997 Ford Ranger AC Compressor kicking on and off every 10 Turning When System Is Off, Noisy. You wouldn't want to replace the clutch, only to have the compressor itself fail catastrophically a few weeks later, shooting metal debris into the system. The way to go is an AirCon system scan to isolate the electrical fault(s). This is the wire that is normally connected to the A/C switch on the vehicle, and controls the clutch/pulley assembly. How long it stays engaged is determined by pressure switches in the refrigerant lines. The compressor clutch is the electro-mechanical device that turns your AC compressor on and off. Would really appreciate help on this. She recently ran her air conditioner and it never got cold with it being about 80 degrees outside. According to the instructions, it should be between 35-45psi so I got another can. Anyway, the ac has always worked great, but this year when it started warming, it was just blowing warm. Then look at the front of the compressor clutch. But first, know some facts about an AC clutch compressor. Hello Again Lisa. Replacing The AC Compressor Clutch. So I just got ac in my car again and bought a new belt and recharge the ac. The compressor clutch solenoid is shot. as the pressure comes back up the clutch will cycle back on. how can i test the clutch cycling. I just replaced the timing belt and now the AC compressor cycles on and off every few seconds. A/C-HEATER SYSTEM 1995 Chevrolet Tahoe 1995 AIR CONDITIONING & HEAT General Motors Corp. vw tdi compressors don't cycle on and off. It will be turned off by the Thermistor to prevent the Evaporator from Freezing. Automotive Air Conditioning Information Forum (Archives) 2001 Suburban just replaced compressor turn on rear AC and compressor turns off. 2) It is most definitely the AC compressor clutch. turn on the air. The clutch on the compressor stays on when switching from low ac to max. The coil can open on occasion and once the wire breaks internally, its done until the clutch is replaced. Typical Subaru Air conditioning Problems explained. AC Compressor Clutch turns on and off - posted in Virtual Mechanic: Any ideas on why it would act this way? I filled it up to about 20psi and it was working ok but not quite cold enough (just cool). What does this mean and how can I fix it? Oh, the blower works fine and both the inlet and outlet pipes to the accumulator are about equally cold. IT IS A BAD PRACTICE IRRESPECTIVE OF THE KIND OR MAKE OF AUTOMOBILE. Once the switch turns the compressor off the pressures wil begin to equalize. Compressor Clutch Basics. A/c was clicking so took it in for some work. However, now when I turn on the AC (normal or max) the compressor seems to kick in only for about 2 seconds then turns off. If I select AC on either of my vehicles, it will run no matter where the temp selector is set. (4) bad compressor clutch. Tried it again and same noise and also tried to turn on air conditioner with same results and car choked out and quit. It is low on freon and that is the reason for the cycling. There are temps where the AC won't run, the pressure switches and sensors will take care of that and turn off the compressor if the system is in danger of. If the care is high milage (110,000+), I usually recommend a whole compressor because I hate doing a clutch and the compressor go out shortly after. This switch is located on the metal canister next to the compressor. The temperature of the unit is controlled by the clutch cycling and that switch is what cycles the clutch. Where to Start AC Clutch Diagnosis. Would really appreciate help on this. If I had the whole compressor replaced It would have cost at least 1,000. An A/C compressor bypass pulley is a quick fix to quiet a car or truck’s noisy A/C compressor. When power is applied to the clutch it engages to turn the compressor. Anyone got a clue? How to Diagnose and Adjust an A/C Compressor Clutch in Car Truck. my old ac compressor starting clicking on and off every few seconds then it would stop for a while then repeat the cycle,when i turn the selector to floor it would stop,i guess this keeps it off. Nope -- I could see the compressor was not turning (center portion was stationary). Sorry for waiting. So then the question is if the AC compressor is short cycling and causing the fan to cycle. Increasing the air quantity above that level turns off both the compressor and blower. A 1999 Silverodo has its own drive belt, and a top off for the system. Repairing a Jeep JK AC Compressor Clutch. Before making any final decisions, you need to perform a little troubleshooting […]. When power is applied to the clutch it engages to turn the compressor. I would welcome any ideas and suggestions. When you turn your air conditioning on, the A/C compressor clutch is the first part to move. An air conditioning problem has reared its ugly head with the warm weather coming. It's not the fact that your air conditioning system is cycling that is a problem, but the frequency that indicates problems. The AC compressor runs all of the time after you turn it "on" and then "off". If it's not, continue reading in the following sections to uncover some common causes of a car AC clutch that won't engage. Faulty Compressor Clutch. I have a 1997 Saturn SC2. The pulley bearing slips over a sleeve outside the shaft, so the pulley moves freely. If the pressure switch detects pressure and has power and has not failed, the clutch will engage. While the clutch pulley turns whenever the engine is on, the compressor only activates when AC (and in some cases defrost) is in use. What does this mean and how can I fix it? Oh, the blower works fine and both the inlet and outlet pipes to the accumulator are about equally cold. This can typically be fixed by turning off the air conditioning unit and letting the ice melt, then checking the air filters, cleaning or replacing dirty ones. The compressor should turn off at about 24 psi to 29 psi (depending on calibration of cycling switch). Connect a test light between compressor clutch battery feed circuit (Dark Green wire) and compressor clutch ground circuit (Black wire). I would make sure the AC compressor is coming on and the compressor clutch is engaged and turning the compressor. Bruce P Dodge Dakota 12/06/2001 20:08:22: RE: A/C clutch on/off IP: Logged Message: The operation of the AC compressor is clearly documented in the service manual. The compressor has a pulley and clutch assembly on the front to allow the belt to always be attached to the engine, and to also allow the compressor to engage and disengage with the clutch. The compressor will not cycle off when the A/C is on. The pressure switch looks new like it was replaced and the system tubes etc. Clutch does not engage and just makes chattering and scraping sounds. Compressor turns on and stays on when I turn the A. My 96 s10 is pissin me off. The car runs fine, but when I turn the AC on, I hear a loud squeal when under low RPMs (such as when idling at a light) which lasts for a second or two, stops for a second or two, and repeats. as the pressure comes back up the clutch will cycle back on. A faulty compressor clutch can be replaced but it is generally recommended to replace the whole compressor to save time and additional cost. 5 50k the compressor not engaging when i turn on the ac. So depends on outside ambient temp how long compressor runs. The AC compressor will normally cycle on and off while it's in use, depending on the demand for cool air. All cars run the AC compressor when the defroster is on. AC was always good, until recently. AC has always worked fine until now. i then checked the pressure with the car off and it was at about 100 psi. When it's not driving the compressor, the clutch pulley turns on a double row of ball bearings. I've done all my research and am fairly certain the problem is the air gap maintenance on the AC compressor clutch (let me know if I'm wrong). if the clutch is bad, replace the whole AC compressor. When it's not driving the compressor, the clutch pulley turns on a double row of ball bearings. Last night the ac started blowing cold and was this morning then started back on the compressor turning on then off. AC has always worked fine until now. I took mine into the dealer for this problem, they said it was normal, but didn't have any more details to offer. Left as is, this would burn out my new compressor. That's why it wasn't turning on. the 9th gen has had alot of problems with the ac the ac clutch goes out in most 03-04, and my wifes 04 the ac relay blew, the clutch is the noise you hear it is turning on and off, if your ac blows cold, then sometimes warm the clutch is bad. I've NEVER had a seconds problem with the AC. I first checked all of the fuses and all of them were fine. Turn the air conditioning controls to MAX AC and start the engine. ) and when the clutch engages it overloads the engine. Turn on your AC even if it isn't working, and go to the front of your car to listen to the compressor. When the evaporator coil or cooling coil of the unit gets covered in ice or frost, it can cause the unit to malfunction by turning on and off in short bursts. With the truck off I can reach down in there and move the clutch around a couple inches. Ford How to: Fix Air Conditioning Clutch (Air Gap) - YouTube You can also check to see if the voltage on the coil wire is turning on and off too,just remove the connector again an start the engine,turn on the A/C,and check to see if the voltage to the coil is steady,if the A/C compressor is switching on & off,it could be a bad pressure switch. So what is needed is enough extra heat or residual heat to vaporize all the liquid refrigerant before it leaves the evaporator. When the low-side pressure rises to about 45 PSI, the low-pressure switch closes and enables the clutch. Marquis had a compressor clutch that wouldn't engage. It allows the pulley that's driving your compressor to be disconnected from your compressor, effectively turning your compressor off. Near the rotor is an electromagnet--a coil of wire which produces a magnetic field when current is run through it. Find great deals on eBay for chevy 5. Will low refrigerant level cause the AC compressor clutch to not engage 15 Answers. The compressor turns on then cuts off as if its low on freon but its not. The pulley should spin freely and not turn anything in the compressor itself. Electrical Load shouldn't be immediately applied to any automobile when turning it's engine on. 16) Check for poor connections at compressor clutch. 3) There are three reasons the air conditioning compressor clutch will not engage or turn on. I mean a little like maybe 1/4 a can. Clutch on compressor is not turning. A compressor that frequently turns on and off might be a cause for concern. 1) Dealerships will, or SHOULD, replace the clutch by itself pending on the mileage. AC Low side reading 110 psi with compressor offwhat? VW MKIV-A4 TDIs (VE and PD) but if you have 110psi at system off, then system will turn on for sure. All of these switches were fine and there was 12v on the wire going back to the ECU. Today, I go to turn it on and it's just blowing warm air. If you do find that your car’s air conditioner compressor is cycling on and off too quickly, then it likely indicates that your vehicle’s electronic module is failing. Noticed the compressor cycles. The compressor clutch regulates when the AC compressor should turn on and off. my old ac compressor starting clicking on and off every few seconds then it would stop for a while then repeat the cycle,when i turn the selector to floor it would stop,i guess this keeps it off. Subject: AC clutch help. I am no expert on this, but from my experience, when the the compressor is off, the pressure in the system equalizes. If I select AC on either of my vehicles, it will run no matter where the temp selector is set. The way to go is an AirCon system scan to isolate the electrical fault(s). The compressor will continue to be on unless WOT is reached or the pressure cycling switch opens. Is there anything else I can check or miss with before I know I have to replace it, could it possibly be a different problem than the A/C compressor. It may just be internal corrosion if the compressor was not sealed at the ports. And it was. as the pressure comes back up the clutch will cycle back on. Have the guy out to replace the compressor/dryer/r134 etc. But then when I hit the ac button the compressor engages and you hear this loud and i mean LOOOOUDDDDDD squeal/skreetch!!!. It is engaged and disengaged as needed by an electro magnetic clutch. Replied by wysetech on topic Air conditioner Compressor Cycles ON/OFF That car has a cycling compressor clutch switch (CCOT) type system. if the clutch is bad, replace the whole AC compressor. However When I went to take a look the AC clutch kept engaging for a few seconds, and then would turn off for a few, and kept going in a cycle. The AC compressor is powered by your cars engine via a belt. Is this normal? Seems to be working. Did not want to charge the system if there is refrigerant at the correct level. I know this will happen if you put too much refrigerant in it but I have tested the pressures and everything is fine with that. When the problem starts to show itself, cooling will stop during warm weather after running for a while. IF the clutch does not engage, I would first guess yoru compressor is locked up. Dear all experience people, I have 2003 Lincoln Town Car, it's been good with me since I had it brand new but last month the AC had problem and I already try the best to fix it but the compressor is still not engaging, if I connect directly pin 1 and pin 5 of the relay then the compressor was engaging and AC cold but I can't stop the compressor until turn off the engine. Vehicle Level Heating and Air Conditioning Compressor HVAC Compressor Clutch Service and Repair Service and Repair Notes DENSO A/C COMPRESSOR REMOVAL NOTE: The compressor clutch assembly can be serviced with the refrigerant system fully-charged. So next time that your air conditioner compressor rapidly turns on and off in your car, it may not be due to low freon levels – but because it is over-charged! Those cheap low-pressure testers that come with the charge kits only tell you part of the story. Turns off when turned off. Any help will be greatly appreciated. If there's no power, swap the ac compresor relay. I've tried to search the webz and see that it may be the clutch or it could be the compressor. The compressor should turn off at about 24 psi to 29 psi (depending on calibration of cycling switch). so my AC works, however It isn't super cold air. 2) Loosen idler pulley nut, relieve tension on belt and remove belt. My AC works for a while then suddenly gets humid, then full hot. And the clutch is what starts and stops it. I first checked all of the fuses and all of them were fine. Yes, it is easy to blame a mechanical system but your car’s compressor system is engaged by the clutch and that, in turn, is driven by the ECU (electronic control unit) for the air conditioner/heating system. My 1997 F150 4. Thought I try to put some 134 a in( or whatever we have decided to call it by now) lol. A quick way to confirm compressor clutch failure is to manually turn the AC on and off. The fact that it cycles on and off is either low pressure OR the trinary switch. turns on for like 3 seconds and then turns off for 3 seconds. 0 liter, standard transmission So yea on really hot days my AC compressor cycles on and off continously. Engaging the AC compressor clutch at home is not rocket science. To check the power, turn on the car and press the ac compressor switch. Gentle prying has not moved it. I've been reading for a week or so about how AC systems work and problems they could have. When the switch goes bad, it will no longer be able to measure pressure and will leave the clutch engaged the entire time. The clutch on the compressor is what allows the pulley to engage and disengage from engine power so that the compressor is only turning when it. Driving a 2009 G6 GT 3. Causes of Air Conditioner Compressor Problems. You also need to check ,the high pressure switch on the circut and you should also have a thermal switch at the back of the compressor. If it is turning, then the clutch wire or compressor piston may have broken. AC Compressor clutch. You can also use a jumper wire to jump the two terminals that pass electrical current onto the air conditioning compressor. The Nissan Path : View topic - Ac compressor question. The inner mechanism of the air conditioner compressor (clutch I presume) was not all on, or all off, but intermittently spinning and stopping. You said it goes from low to high. Turn off AC ,leave cab fan blower on. The compressor will not cycle off when the A/C is on. The following readings were taken using an OTC 500 meter and OTC current measuring clamp; they are off of a 1986 Le Baron: Clutch resistance: 5 ohms, as measured at the clutch connector. Turn on engine, open hood, turn on compressor and you should hear a click and see the compressor clutch start up and turn the compressor. Re: Freightliner wiring diagram ac compressor: richard lynch: 6-20-11 : AC compressor clutch not engaging. IT IS A BAD PRACTICE IRRESPECTIVE OF THE KIND OR MAKE OF AUTOMOBILE. corroded & slipping)? I'm thinking if it were a bearing, or an internal compressor failure, I'd hear the noise all the time, or only when the AC is on. Replied by wysetech on topic Air conditioner Compressor Cycles ON/OFF That car has a cycling compressor clutch switch (CCOT) type system. It was not. The compressor will continue to be on unless WOT is reached or the pressure cycling switch opens. It is basically a magnet a/c compressor clutch is the. If your AC won't turn off, you might not notice the irony of the situation right away. The clutch is not engadeing when I turn the ac on. I am no expert on this, but from my experience, when the the compressor is off, the pressure in the system equalizes. (3) bad A/C compressor relay (which you have already checked it seems). What could be causing this and how do I fix it?. Your AC should only run when it is either on the two AC settings or when it is on the Defrost only setting or the mix of defrost and heat to the lower vents. I have a 94 Ranger w/2. When your AC is switched off, or the compressor isn’t running, an electronic clutch is used to disengage the pulley from the compressor so the engine belt can still run. With AC on max, I popped the hood and checked to see if the clutch on the compressor was engaged. Faulty compressor clutches could be the result of an overcharged system. my old ac compressor starting clicking on and off every few seconds then it would stop for a while then repeat the cycle,when i turn the selector to floor it would stop,i guess this keeps it off. He did but didn't fix the problem. In my car I can turn the AC (compressor) on or off and choose where the air comes from as separate functions. If test light illuminates, go to next step. When you re-charged the air conditioner compressor you need to turn your fan motor on high , and it should be on its coldest. It's not the fact that your air conditioning system is cycling that is a problem, but the frequency that indicates problems. 1) Raise vehicle on ramps & remove plastic shroud underneath AC compressor. The compressor looks like a small motor with a large wheel on the end. It was not. In fact,it ’ s very easy to test whether the ac clutch is bad or not. I observed the compressor clutch activity. ok at idle(600-700rpm) when you turn the ac on you can feel the truck somewhat shake, very minute, but almost like a slight misfire. I have a 94 Ranger w/2. Clutch does not engage and just makes chattering and scraping sounds. For whatever reason, he opened the loom at the compressor clutch and found a power diode. It is basically a magnet a/c compressor clutch is the. If #3 is the case, try manually engaging the clutch. Here's how it starts: you notice it's too hot in your space and the AC is not achieving the set temperature. The AC compressor will normally cycle on and off while it's in use, depending on the demand for cool. Excellent! The dealership told me the A/C compressor was not turning on and would be 1200 dollars to replace. An air conditioning problem has reared its ugly head with the warm weather coming. I don't even hear the compressor turn on or anything. What is an AC clutch compressor. The inner mechanism of the air conditioner compressor (clutch I presume) was not all on, or all off, but intermittently spinning and stopping. This is when the clutch bearing is active and would be heard if it were failing. ok at idle(600-700rpm) when you turn the ac on you can feel the truck somewhat shake, very minute, but almost like a slight misfire. All of these switches were fine and there was 12v on the wire going back to the ECU. Now it keeps freezing up and the compressor won't shut off. 35 is low but should be sufficient charge to run the compressor. When it come on it tries to cool but the compressor doesn't stay on long enough. Have the guy out to replace the compressor/dryer/r134 etc. It was not. If it is not, check if the power wire to the compressor clutch is getting power. Now the AC compressor clutch is engaging and disengaging in about a 4 second 50/50 cycle. In normal operation, the clutch cycles on and off regularly. Makes sense. In fact, it is generally recommended to simply replace the compressor rather than attempt even the simplest repairs. compressor drive shaft. AC was always good, until recently. There is a clutch at the end of the compressor. That style of compressor does create quite a bit more drag when running, but still would only run for a very short time in colder weather. by Bob O'Neill and Bob Lincoln. Checked the fuse and it is good. Also check the ac compressor relay and if questionable switch it out with a known good used one. The AC clutch is on the front of the compressor where the belt rides. The car runs fine, but when I turn the AC on, I hear a loud squeal when under low RPMs (such as when idling at a light) which lasts for a second or two, stops for a second or two, and repeats. If the A/C clutch relay is stuck or the switch is faulty then the clutch will stay engaged. A few days ago the AC just stopped blowing cold air. All settings are about user. the AC compressor clutch should engage when you turn on airconditioner if AC compressor dont come on and fuse okay compressor clutch is open or low on refrigerant you need check your AC refrigerant low pressure side and high pressure side need a manifold gauge set. With the truck off I can reach down in there and move the clutch around a couple inches. After the AC has run for 15-20 minutes it will turn off. If the compressor never cycles off and on, then there are two possibilities. ’ But if the Voltage Switch says: ‘Nope, the throttle angle is still too high’, the air con compressor will stay off. hi in my 2008 altima 2. After first long drive, ac slowly stopped putting out cold air. Now the air conditioning compressor wont come on. This allows the compressor to shut off even while the engine is running. the whole time i was filling it up the compressor kept cycling on and off, on for about half a second and off for 5 or 6 se. Last night the ac started blowing cold and was this morning then started back on the compressor turning on then off. With a blown fuse, the compressor obviously won’t turn on. When the compressor doesn't turn on at all, it can mean a couple different things. If it fixes it, replace the relay. And the clutch is what starts and stops it. There are basically three sections to the AC system; the sensors (high and low pressure sensors and the AC on/off switch), the command unit (the powertrain control module- PCM), and the "doing" components (the compressor clutch relay, compressor clutch, and the compressor). I believe it should shut off when in defrost mode when outside air gets cold, but I do not know if this is true. There are temps where the AC won't run, the pressure switches and sensors will take care of that and turn off the compressor if the system is in danger of. Custom chasis on Itasca Horizon motorhome. This magnetises the clutch drive plate thus turning the compressor. Cycling is part of the normal process through which your HVAC operates. My 2002 Chevy S10 A/C unit goes on and off 5 Answers. To check the power, turn on the car and press the ac compressor switch. Immediately pulled off the road after turning the defroster off. Check clutch electrical circuit for proper voltage per OEM specifications. It is the part in the center of the pulley--the A/C clutch-- which engages when the A/C is turned on. The clutch would kick on and off until it started to blow hot air. I know they cycle repeatedly but this is too fast to cool. That’s because the clutch pulley is connected to a field coil which can be magnetized with electric current. After that, I only needed to read the compressor replacement procedure, to convince my self that I don't really want to deal. If the compressor never cycles off and on, then there are two possibilities. If the ac clutch does not engage during the ipdm test then most likely you have an electrical problem. And the clutch is what starts and stops it. Can not find a fuse for the clutch. The ECU then outputs a 12v signal to energize the compressor relay which in turn energizes the compressor clutch. The temperature of the unit is controlled by the clutch cycling and that switch is what cycles the clutch. The pulley should turn but the compressor should be off. If it still has 12v then the clutch coil is bad and the circuit is opening as the coil warms up from being on. Clutch control assemby - the electronic part of the end of the compressor (£500). This can be done several ways, but the. There is a clutch at the end of the compressor. Would really appreciate help on this. Once in a while, I want to turn off the AC but pressing the ECON button, and the compressor is still runningI am guessing a faulty sensor or a stuck compressor clutch. The clutch on the compressor is what allows the pulley to engage and disengage from engine power so that the compressor is only turning when it. I heard a "click" and could now see that the compressor was turning (center was spinning). Causes of Air Conditioner Compressor Problems. Discuss Possible AC compressor clutch pulley gone bad? in the alt. Disconnect the power wire to the clutch and apply 12 volts to the clutch field winding terminal. When the ac is blowing hot, turn the AC to max cold and check if the clutch is turning. The clutch is the center area. first thing check AC compressor fuse. When you turn your air conditioning on, the A/C compressor clutch is the first part to move. The clutch will not engage if insufficient A/C system pressure is not present. After compressor installation, turn the compressor shaft a minimum of 10 revolutions to remove excess lubricant from the compressor. Turn the air conditioning controls to MAX AC and start the engine. Run the engine at 1,500 to 2,500 RPM. Repairing a Dodge Ram Air Conditioning and TIPM. Since my coolant/thermostat has been fixed, my AC has never turned back on and now my Compressor clutch won't engage. Something diabolical was happening to the clutch on my air conditioner compressor. In those cases, you would require an immediate change service of the same. I diagnosed it as a shorted out ac compressor clutch. In simple terms, an A/C Compressor is a pump. In fact,it ’ s very easy to test whether the ac clutch is bad or not. If the compressor clutch engages and there is noise then most likely its internal. My AC compressor is turning with the serpentine belt, but when I actually turn on the AC the compressor clutch does not kick in so the AC does not actually activate- how can I get the compressor clutch to engage?. I am worried about damaging my compressor. com FREE DELIVERY possible on eligible purchases. Sometimes is sounds like the compressor tries to come on and cannot and then clicks off. Compressor doesn't turn on. Scope the A/C compressor rpm sensor on the white wire at terminal A13 (terminal 13 of connector A) at the ECM and look for a clean, consistent AC sine wave signal with the. Third, the A/C compressor relay is a $4 throwaway part, like the fuel pump relay. Have someone start the engine with the A/C off. Okay, I drove the truck until the A/C started acting up. I took mine into the dealer for this problem, they said it was normal, but didn't have any more details to offer. A compressor that frequently turns on and off might be a cause for concern. Inspect the clutch located at the front of the AC compressor and make sure the clutch rotates freely. The AC compressor will normally cycle on and off while it's in use, depending on the demand for cool air. Then look at the front of the compressor clutch. The compressor will not cycle off when the A/C is on. Once the AC clutch obviously disengages itself and begins blowing warm air, turn off the AC with the button on the center console. The low-pressure switch tells the car that the clutch needs to engage and disengage and will shut off the A/C compressor. After the AC has run for 15-20 minutes it will turn off.