The AC compressor drive belt rotates the compressor pulley at all times when the engine is running. During drive time from dealer to home 70km, I was feeling the engine is getting less power randomly. I'm strictly speaking of the compressor's magnetic clutch here. It worked! Well, I checked the static pressure after the car sat for a bit and the reading was over 100 psi – note that this is on the low-pressure side. Got home and began to slowly put the R-134a into the car air conditioner system with the AC turned on and the temperature set fully to cold and the blower fully on. 99. Great post: very informative. When the A/C is activated, the compressor clutch transfers power from the engine’s crankshaft to the pulley mounted on the A/C compressor. When the switch goes bad, it will no longer be able to measure pressure and will leave the clutch engaged the entire time. after three weeks of frustration trying to figure my system out ,I happened across this post and bingo. So, back to the hoses. Turns out there is a second belt – an accessory belt – that controls the A/C compressor. the techniques described about letting some refrigerant out of system was spot on. Get a great deal on a quality A/C Clutch kit.A/C Clutch Kit.A/C Compressor Clutch Kits include the compressor clutch, which engages and disengages the compressor when the A/C is switched ON and Off, and other related components. Unusual cycles, such as when the compressor runs for a long time without stopping, shuts down briefly, then runs again for a long time, call for air conditioner repair. After reading this last night while searching for solutions on my ’07 Civic, I went out today and bought an inexpensive gauge set at a local auto parts store, and low and behold, my high side was reading in the mid-400 psi range. When its on, the air is very cool, but when its off, don't know how long will it change its mind again. I had a cheap single-gauge kit that only showed the low side pressure. Lastly, if you’re ever going to service your AC system yourself, after my experience, I highly recommend getting a gauge set for both the high and the low side. Thanks a lot for your info. Tags: AC cycling too often, damage cycling switch, Poor A/C performance, Copyright © 2021, All Rights Reserved, Auto A/C Repair LLC. BTW. If the compressor clutch is not engaging, there are many possibilities. Like the thermostatic switch, the turning on and off of the pressure cycling switch controls the operation of the compressor. Get it as soon as Mon, Jan 11. Then, I attempted to turn on the air conditioner on in the car last week and again – very bad squelching noise coming from the car when the AC was on. But, he did tell me that my AC was cycling on and off and it needed to be charged. With recirculating the air and the outside temperature around 80 degrees, the car was putting out about 44 degree air from the A/C vents. You can rent one at Auto Zone free. I only took out a lil bit at a time so is that a bad compressor?? !We were going to do 500 in repairs until we realized its also over charged!!! 1. Thank you for posting your comment. This is an otherwise well running 1998 Taurus. Bleeding some pressure from the high end did the trick. This is part of the programming that is built into the electronic system that takes all extra systems that might rob power from an engine under acceleration and redirects it to the engine itself. I then called a co-worker that had a full set of hoses that can be used to check both high and low pressure. If you begin to notice that the AC system is no longer functioning as it used to, and you suspect that the clutch cycling switch may have a problem, consider having the switch tested and replaced if necessary. Catch me. I then got my temp prob out and found the temp to 55.3F. Then, when your compressor is off, the pressure will rise again and it will turn back on. i have an 05′ ford & i did the “do it yourself” freon thing & had the same thing happen & was dreading a $1k fix..thanks so much for posting.. Had a new trane unit installed in my house. A/C cycling switch range of operation. Didn’t even make it very far and the compressor started kicking on and off again! Solution: Refrigerant leaks can be dangerous, call a local HVAC company to find and fix the leak. AC Clutch kits are in-stock and available for all makes. My AC is always spending even if the AC is off does the AC always going to be running because I never had a clutch engage is this supposed to work that way with the AC compressor always running can you please give me a little bit inside on what's really going on because that the air is not circulating would be cold . The OP is the best I’ve seen for person-splaining conditions and ramifications for vehicular AC compromisation. My AC was recharged on my 09 Accord and the air stopped blowing cold as well as the compressor started cycling on and off repeatedly. I only intend on bleeding off a small amount to see if it will help! Stephen . That's why the ECU can cut off power to the compressor's clutch coil so that it disengages the compressor whenever it feels it's necessary. I am having similar problem with my 2000 Avalon, and would like some specific help. The power to run the compressor clutch coil goes from the battery, to the AC Clutch Relay, somewere in the engine compartment fuse box, then it goes to the positive side of the AC compressor clutch coil; goes thru the coil, activating the compressor, and then goes to complete the circuit through another switch (high pressure protection switch) in the back of the AC compressor and finally reaching negative or … Called up my mechanic and he basically told me the same thing – he said that if the compressor was rapidly turning on and off, it was because it was undercharged. Probably you have the fix by now but maybe someone else….? We’re just a meagar few backyard mechanics. I added a reply to you but not in the proper spot. Be careful what you post online. Again, this is normal operation.If you do find that your car’s air conditioner compressor i… You should never guess with refrigerant, you should have evacuated the system from the beginnng, and then weighed in the correct amount. Once again, many thanks for the owner for the post! A 12-ounce can would be just more than half of it’s capacity. Does this sound reasonable??? Wouldn’t you know, it actually was reading higher than it did when the system was overcharged. it hit 350 – then 375 – then 400 – then just shortly after, the compressor popped and shut off. Ok, I knew that AC start is pulling down some Power, which is normal, but the “up and down movement” on the engine was not normal. I switched of the AC, and this time the engine was running fine. If you get that the air conditioning (AC) compressor clutch is not engaging in your car, you might need to get some answers. When the pressure increases to about 47 psi, the switch closes the circuit, causing the clutch to engage the compressor. Then it would pop and kick on again. After a few misses, I found your article and knew instantly what was wrong with mine. I think I overcharged my system but only have the means to remove the coolant from the low pressure side? So I took it down to a guy I know that works on cars for a very affordable price. When low-side pressure decreases to about 25 psi, the pressure cycling switch opens the clutch’s coil circuit to disengage it. Wow! Thanks! The rate of how fast it will cycle is determined by the outside temperature. The low-pressure switch tells the car that the clutch needs to engage and disengage and will shut off the A/C compressor. I popped off the connecter from the low side and began letting out a little refrigerant at a time, until the high gauge began to drop and the compressor began to stay on. Similarly, the AC Compressor Clutch engages and disengages the compressor of the air conditioner. Excellent ! After taking some out, the compressor stopped kicking on and off – and the high pressure then stayed fairly stable between 325 and 350 psi. A defective compressor clutch can be replaced, but it is generally recommended to replace the entire compressor to save time and additional costs. We will see, as this is just the first day and the a/c boys are still here. In this article, you will learn what you can do during such a situation. Show Less. The Honda Civics can hold up to 22 ounces of R-134a in them. If anyone is looking for the gauge set I used, it’s available from most of your big name chain parts stores. I checked the Freon level and it seems fine. Good and organized post, I noticed also if there is a low charge of gas, it will the same rapid cycling and I think this happens to avoid the compressor from being damaged.Thank you for sharing your post. My question is how do i go about bleeding it, does the engine need to be on or off, high side or low side? The compressor clutch regulates when the AC compressor should be switched on and off. How does an A/C Compressor Clutch Work? When the A/C clutch would turn off so did the radiator cooling fans. One side goes up and the other goes down while the AC is running. Low side system pressure is regulated by the cycling of the compressor to prevent evaporator freeze up. Several conditions cause short cycling, including a faulty or obstructed thermostat, leaking refrigerant, icy coils or an HVAC system that is too big for the building in which it is installed. I haven’t bled any of the R 134 off yet but I’m hoping this will be the fix to my problem since it seems like it’s been the solution to everyone else. I said – “Is it because I overfilled it?”  He agreed and thought that I may have overfilled it – but said he hasn’t ever noticed a car doing that before. Releasing freon into the air is illegal, as is most things these days. That is exactly what I was experiencing kick off on the high line air in the system bled it a little rpm it to 2700 noticed kicking stopped after several tries added compressor oil easy on the freon134a noticed air in the system than bled it a little until system was operating normal . After all, we aren’t factories and such. Lockout on Clutch Sensors: Most modern cars have their AC clutches turned ON and OFF using high pressure, low-pressure switches, and level of the compressor oil. Very good information for the DIY car guy/gal out here. Well i think he added too much and now my ac is cycling on and off and blowing warm air! S, now, when I finish my work today, I will try to find service to check the right amount of the gas. I believe now its over filled. 7. Thanks a ton, I will post results back to you all here. Onto Google I went. Compressor strongly cycles on and off and pressure fluctuates between 20 and 45, low side port tube is frosty but no freon will flow into system. I had the exact same issue, and Rob’s post pretty much mirrors my experience. & the AutoZone guy was being nice and helped me add it. Thank you so much, you saved me a ton of money with this fix! Maybe i've got an idle/crankshaft sensor problem and the AC compressor is trying to tell me that. Then get a scale and weigh in the exact amount of freon. We weren’t sure what it was and went on about the day. Vented the refrigerant and the problem seemed to go away. If the ac compressor is turning on when you have something on (floor, heat, vent) then this is normal. You will also notice air conditioner compressor cycling when your car is under hard acceleration, like when you are pulling onto a major freeway. The compressor was still clicking on-and-off so I kept bleeding the line until the compressor kicked on one last time and stayed on! So take your car to the mechanic right after you find the problem with the AC compressor. on off…every 5-7 second. But, I explained to him how it was working fine – and somewhat cooling – before putting any refrigerant in – then it started kicking on and off after adding 3/4 a can in. The car no longer cycled the compressor rapidly after taking some R-134a out of the system and it cools very well. General procedure to remove and reinstall a/c compressor clutches. it worked for me . Problem fixed – no more squeek! It is normal for a vehicles system to cycle the compressor to prevent the internal pressure from exceeding certain maximum pressures within the system. Or by pressing low side port schrader type valve with screwdriver, etc (keep hands away from any Freon) ? A hefty sum to replace the compressor recycling the RPMs get low.... Very cold out or was raining/wet, I requested the seller to check both high and low pressure expel freon. Be switched on and off, then I started to have him the... But she states at highway speed, it has educated me off switch of the air conditioning.... 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