A/C compressor clutch.

[greenvan]

My A/C compressor clutch is working erratic. It goes on and off and the compressor is not working right. It was new 6 years ago. Could this be a bad clutch relay or a bad compressor clutch?

 

[seems fishy]

Just a question,what year is your truck?I am asking because you said the compressor was new 6years ago.Is this your 99,Ram Van?If it is your HVAC is 27years old. Was it(compressor TRS105 that is not a variable displacement model) OEM or aftermarket,or rebuilt,used(sometimes people say new when they mean new added to the truck,but it was sourced from another vehicle),or something else even ,creating a Frankenstein HVAC system.
When you changed the old compressor was it done professionally.Usually if a compressor goes it can contaminate (clog the system with bits of metal)the system and often the system should be cleared with a chemical flush and after nitrogen being blown through (the system).
When you are saying erratic does it cut in and out without out going full cycle?I don't think we are talking about,a variable displacement compressor given the age,unless it was put in place of the OEM.That behaves differently.
Can't say for sure unless details are more clear.I will make a stab in the dark with the post you made and say your low on freon,as that is first suspect when the compressor isn't behaving normally,and the system is geriatric.Unless you can clarify what ...not working right means.The TRS105 is supposed to go on and off(that is what cycling is).The time between cycles is important but is meaningless with out a set of manifold gauges,to give length of cycles and pressures.,Is it blowing cold air?Is your system still using r134a or been changed to r1234yf...when the system was worked on six years ago.You can't mix the two.They have different valves and fittings.They use two different PAG oils.Mixing will contaminate the system and be corrosive.
To be honest and realistic without more detail your issue can be any thing,especially if it's 27y/o.Can you give some more detail?I am sure lots has happened to this system over the years.It is terrific it was working this long.In a few more years this will be a historic vehicle.

 

[greenvan]

It is my 99 Dodge van. Compressor was bought at Auto Zone and replaced at an A/C shop. Over the past 6 years, I had several leaks and had to replace several parts. One, a fin sensing cycling switch I had to get from a junk yard because Chrysler is not making this type anymore. I started charging it myself because of all the leaks. I bought a set of gauges from Harbor Freight but they don't seem to be high quality. Using R134a. One interesting thing is that the gauge hoses are very hot. The high pressure line is very hot. Low pressure around 35. High pressure around 50. I have the factory service manual. It says one possible cause is a restricted expansion valve. I checked all the low and high pressure switches and others and they all work. Then I let out some freon and the clutch started working for a longer time.(5 min.) It is now blowing cool air, but not real cold air. Also the clutch seems noisier than it was before. This all started when I added a can of freon because the air was only blowing mild, not warm , but not cold. By the way, the expansion valve was replaced 6 years ago. This is a confusing situation. Why does It blow cooler air after I let some freon out?

 

[alpinegreenneon]

Rapid cycling of the AC compressor is usually low refrigerant.

 

[seems fishy]

IT BLOWS A LITTLE COOLER BECAUSE INITIALLY YOU OVERFILLED IT.When you let some freon out the total amount was closer to the proper amount of freon.More is not better with freon.Exact amount only .I am guessing you likely did not pull a vacuum when you've added freon on your own(not sure) but if you topped it up in the past with those small diy kits(adding to the low side with the vehicle running),then you have moisture ,and when that mixes with freon it becomes corrosive.Personally,it is time to bring it in for a professional service to have your system evacuated,and they can pull a vacuum ,check for leaks,dry your system and recharge it.They can put in the proper amount of freon and oil back in . The proper amounts are critical as overcharging can blow your compressor.If it is now noisy maybe the reeds are blown or damaged,from overfilling.[Those little diy cans can cause more issues than you know.Worse if they contain a stop leak additive.Stops the leak and also plugs everything up].That is why when you let some out things improved.Also you should capture the freon when you let it out because of CFC's.The total amount the system takes is somewhere under the hood on a sticker.Usually 2pounds average.When you add some from a can you are guessing what the total amount is.So if you were not pulling a vacuum before bring it in to get a pro HVAC service to get that corrosive freon out ,because there is air/moisture in the system.It will never blow cold and does damage.GOOD LUCK

 

[greenvan]

The A/C shop that changed the compressor vacuumed the system before charging. But it did not seem to blow as cold air as when I bought it. The reason the compressor had to be changed was that it was making a noise. I went back to the shop and they got in and turned on the A/C and said it was blowing cold air. I disagreed , but they started arguing with me so I left. That was in 2020. Since then I have been living with the A/C blowing mild air. At least it took the humidity out. With this big heat wave we are having in Florida right now I tried to put a can of freon in with one of those single hose lines with a gauge. The label under the hood says the charge is 2.13 lbs. for the front unit. One of those cans is 12 oz. This van used to have "rear air". I never used it and developed several leaks. So I disconnected all the lines and had a TIG welder weld all the aluminum lines shut. Now I only have front air. That is when I started charging it myself. I bought a vacuum pump and those Harbor Freight gauges. I bought a leak detector off E-bay and found a small leak at the low pressure port. I just pushed on the schrader valve for a second and it seated properly and that fixed the leak. I added a can of freon and that is when this problem with the compressor clutch started. I am sure the problem is with the correct amount of freon charge, like Seems Fishy says. These factory service manuals are worth their weight in gold. That A/C shop charged me $1000 to install the compressor and add freon.

 

[Ritchie_Rich]

Sounds like low pressure switch cycling due the low refrigerant. Most likely you have another leak.

 

[seems fishy]

29"hg is the prescribed vacuum to pull,nothing less.Leave the vacuum on for at least 20 minutes to dry your lines,but this alone can cause leaks ,where they may not exist currently.My one new question is DID THE FREON PRODUCT you used contain a SEALER TO STOP LEAKS? Many do since the rationale is you have a leak and you are adding freon so they add it to stop the leak.YOU mentioned about issues,after using the can of refrigerent.
Make sure the system holds the vacuum after removing the vacuum pump for at least 15minutes
Your h valve is suspect if you inadvertantly added a sealant with the freon because it has the part that meters freon before the evaporator,and the smallest opening of the system and it may have become clogged.Your compressor is working if your hvac still removes humidity from the truck.Are you replacing the proper PAG oil(it may be Ester ,I do not recall for your truck).You have removed,(evacuated) the oil with the freon before you previously pulled a vacuum .The little top up cans will do nothing correctly if your systems oil is down.You have to replace the oil,you removed.As with freon the exact amount,not more not less.
Since disconnecting the rear evaporator lines the amount of freon will be less for the system obviously but by how much I do not know.ARE YOU SAYING the sticker on the truck indicates different amounts of freon based on the rear being not included,with the front A/C ( "the front only being 2.13 lbs"?)The amount sounds okay BUT,The system should be ONE AMOUNT, it is one closed system .Sounds odd to me based on design that it says front only amount.It will not be more than that amount,and my guess is less now the rear evaporator is disconnected.That said it is a bit of trial and error unfortunately.,as the rear is disconnected,but could have caused you to add too much freon.


You also have replaced the Fin cycling switch with a used one years back.It may be not working.You can test it by removing it and jumping the terminals in the plug.I suggest you read up on that on the internet for troubleshooting that item.It is also a reason for warm air.You can still buy them new on the internet for cheap.

Check the CONDENSOR for freon oily patchy areas revealing leaks at the fittings... Obstructions like bugs leaves etc. clogging the fins, since nothing gets cold if that is not getting air through it,to cool the gas as it returns to liquid state. Do you have a aftermarket,RECEIVER DRYER .It may have been replaced at some point.[I can't imagine a 27year OEM receiver dryer still working effectively]. OEM receiver dryers do not have sight glass,but older vehicles did use them.IF there are bubbles in the sight glass,it meant a low charge of freon.If you can buy a sight glass the amount of freon could be accurately worked out.When viewing it have the freon level JUST AT THE POINT where bubbles do not exist.You can buy this diagnotic tool online for 50dollars.Just saying because presently it is a guess how much freon you need as the rear evaporator is disconnected.
The HVAC shop you used sure charged a premium price but it depends on the parts and hours spent.They probably flushed your system and then blew out everything with nitrogen.That is done often when replacing a compressor.That costs extra...
I get ridiculously high bills when I bring my pets to a vet...
That said sometime if they are sick you still have to bring them in,and it is costly.More than a grand with diagnostic tests.
As mentioned before if it doesn't blow cold air for you and you have tried everything,bring it in to a licenced HVAC technician.I haven't been to Florida in 50years,but I do remember it gets real hot.I know you love your truck and want the A/C to work.Again,good luck.

 

[alpinegreenneon]

I do my own AC and when I replace anything that was leaking, I like to vacuum the lines at least overnight, sometimes even longer, to boil off any moisture. I don't think 10 minutes is enough, especially if it was leaking for long enough to lose most of the refrigerant. Refrigerant and getting AC serviced seems to be more expensive every year. While it's tempting to do yourself, if you don't have at least a vacuum pump and a good gauge set, maybe get it professionally serviced.

 

[seems fishy]

. I don't think 10 minutes is enough, especially if it was leaking for long enough to lose most of the refrigerant.

I AGREE,my post was changed after reading this.I now say 20min. minimum in my post but the longer the better,and overnight if you choose.That will leave no doubt it has been dried.His system is 27years old and I am afraid it is frail to begin with.In my first post I called it GERIATRIC for a hvac system and I don't want to push his luck,as at this point,anything is still suspect.27year old orings are very brittle.I prefer he takes it in somewhere for service.Dodge in 99' and many other of the big3 manufactures were cost cutting back then on their A/C units and having premature failures.I am surprised this one is still,around and that is rare.

 

[JW2 Innovations]

I'd check with a good set of pressure gauges if you know how to do that. Like others are saying here cycling due to low refrigerant.

I also do my own A/C work and have the right tools, but once I had an A/C clutch slipping on an F250 and did the remove the shim trick to get some additional life out of it - 189,000 miles on original compressor. Worked for a bit, but then when I tried to replace the clutch later it was money just blown in the wind. Ended up replacing the entire compressor anyways due to the compressor eating itself/worn out. Moving fwd, I'll never put another clutch on but rather just bite the bullet and replace the entire compressor unit that includes the clutch.

 

[crash68]

29"hg is the prescribed vacuum to pull,nothing less.Leave the vacuum on for at least 20 minutes to dry your lines,but this alone can cause leaks ,

in/hg is a course vacuum measurement for refrigeration work, that's why micron gauges are used.
Don't think I've even caused a leak by pulling too much of a vacuum, I've had many systems under 100 microns. If I remember correctly a new vehicle being charged on the assembly line would have to get under 500 before the system would charge the vehicle. There's 25400 microns in 1"hg
The fun part is determining if you have a leak, moisture, or refrigerant boiling off.

 

[seems fishy]

I agree but this system is 27years old.I don't think he will necessarily get this going again properly without professional assistance.I am not certain if Recover, Recycle Replace,the 3r's,has actually taken place,at all,from what has been said,and as you know everything is done a certain way.I am not sure if he has any refrigerant oil circuIating ,or how much.I prefer he doesn't do to much more as this isn't the best system for anyone to learn on. ALSO,good,HVAC repair shops have great equipment(like Snap On machines,which measured vacuum in hg format)like I used to use,which makes everything so much easier, and precise,compared to what is available here,and they do not use tiny cans of refrigerant(which I am not a fan of)...I do not think he could purchase a larger bottle of freon unless he had a CFC licence.A little expertise goes a long way,as well.I don't do HVAC anymore professionally,I retired,and if I did I couldn't guarantee the outcome for certain.It would be nice to at least start by ensuring everything is done properly,AND there is a bonus if you can actually give advice with the vehicle in front of you,and you can put your hands on it.I saw a lot of newer systems come in and get tagged at 10years old,that required as much intervention but people could not afford it.I am fairly sure there is more than one issue with this.

 

[Ritchie_Rich]

29"hg is the prescribed vacuum to pull,nothing less.Leave the vacuum on for at least 20 minutes to dry your lines,but this alone can cause leaks ,where they may not exist currently.My one new question is DID the FREON product you used contain a sealer to stop leaks? Many do since the rationale is you have a leak and you are adding freon so they add it to stop the leak.YOU mentioned about issues,after using the can of refrigerent.
Make sure the system holds the vacuum after removing the vacuum pump for at least 15minutes
Your h valve is suspect if you inadvertantly added a sealant with the freon because it has the part that meters freon before the evaporator,and the smallest opening of the system and it may have become clogged.Your compressor is working if your hvac still removes humidity from the truck.Are you replacing the proper PAG oil(it may be Ester ,I do not recall for your truck).You have removed,(evacuated) the oil with the freon before you previously pulled a vacuum .The little top up cans will do nothing correctly if your systems oil is down.You have to replace the oil,you removed.As with freon the exact amount,not more not less.
Since disconnecting the rear evaporator lines the amount of freon will be less for the system obviously but by how much I do not know.ARE YOU SAYING the sticker on the truck indicates different amounts of freon based on the rear being not included,with the front A/C ( "the front only being 2.13 lbs"?)The amount sounds okay BUT,The system should be ONE AMOUNT, it is one closed system .Sounds odd to me based on design that it says front only amount.It will not be more than that amount,and my guess is less now the rear evaporator is disconnected.That said it is a bit of trial and error unfortunately.,as the rear is disconnected,but could have caused you to add too much freon.


You also have replaced the Fin cycling switch with a used one years back.It may be not working.You can test it by removing it and jumping the terminals in the plug.I suggest you read up on that on the internet for troubleshooting that item.It is also a reason for warm air.You can still buy them new on the internet for cheap.

Check the CONDENSOR for freon oily patchy areas revealing leaks at the fittings... Obstructions like bugs leaves etc. clogging the fins, since nothing gets cold if that is not getting air through it,to cool the gas as it returns to liquid state. Do you have a aftermarket,RECEIVER DRYER .It may have been replaced at some point.[I can't imagine a 27year OEM receiver dryer still working effectively]. OEM receiver dryers do not have sight glass,but older vehicles did use them.IF there are bubbles in the sight glass,it meant a low charge of freon.If you can buy a sight glass the amount of freon could be accurately worked out.When viewing it have the freon level JUST AT THE POINT where bubbles do not exist.You can buy this diagnotic tool online for 50dollars.Just saying because presently it is a guess how much freon you need as the rear evaporator is disconnected.
The HVAC shop you used sure charged a premium price but it depends on the parts and hours spent.They probably flushed your system and then blew out everything with nitrogen.That is done ofter when replacing a compressor.That costs extra...
I get ridiculously high bills when I bring my pets to a vet...
That said sometime if they are sick you still have to bring them in,and it is costly.More than a grand with diagnostic tests.
As mentioned before if it doesn't blow cold air for you and you have tried everything,bring it in to a licenced HVAC technician.I haven't been to Florida in 50years,but I do remember it gets real hot.I know you love your truck and want the A/C to work.Again,good luck.

Yeah, I was a professional mechanic for 25yrs and I never heard of or saw a leak caused by evacuating the system.

 

[seems fishy]

YES and I DID HVAC FOR 25YEARS TOO,as a licenced technician and had a CFC ticket.I am a licenced bodyman and replaced condensors practically everyday from cars that were in front end accidents.I never had a COME BACK..I have never worked on or seen a 27yo HVAC,that still worked, in that time.That is rare especially for mass produced vehicles from that era . I do not want to be the one to say something that will cause him more issues.I am not even sure he has used his vacuum pump,yet he hasn't said he did,if he did .He doesn't say if he evacuated the system,yet,and I do not think he did.He says he only ever added 1small can of freon,EVER ,and did not say if it had STOP LEAK which is too bad if he did .


He isn't sure how much freon to add as he disconnected the second evaporator.IMO he did not read the tag under the hood correctly for the factory amount of freon.If you have READ ALL the ENTRIES carefully and want to add anything,that is good,and in fact I appreciate it.THE WORST thing trying to help someone like this gentlemans 99Dodge is saying something,having them follow your directions,and then causing more issues.He will BLAME YOU.So NO,I am not going to tell him to pull a vacuum for a long time,as he has 27year old orings etc..This system probably needs a complete overhaul with new lines ,o rings and associated components which would be prohibitively expensive.I am trying to help but have no real idea if he is capable? Performing a proper repair requires understanding how it works in the first place,and he is asking for diagnostic help from people who are remote from the car.Feel free to pick up where I am leaving off.I spent really alot of time trying to help.I am sure you have read every thing I have written.I honestly have nothing else to add and will gladly pass the assistance to be given to all the other members who want to help him.I HAVE spent too much of my time on this already...I SUGGEST,he just bring it somewhere,but gave him lots of ideas where to trouble shoot.To be honest if using quality equipment 20minutes for a vacuum pull is not unheard of.I don't even know if there is any oil left in the system after all the things he did or didn't do.GOOD LUCK helping him but , don't question me.HE HAS NO EXPERIENCE .
BTW,there is a Tornado coming my way and I have to go PLEASE help this gentleman,the best you can .