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Discussion Starter #1
:confused::confused::confused::confused::confused::confused:

I am 67, used to working on my Buick. I am trying to help my daughter; who drives an elderly woman to the Doctor frequently in her 2007 SXT.

Last spring, her first with the car, I had to buy the large refrigerant recharge kit and recharge the system. It worked great for the rest of the year. Now it is beginning to get really humid and on sunny days the car will get too hot. The air is just blowing unmodified. I made the mistake of assuming it had leaked out over the winter & I bought another recharge kit. After I hooked it up I can see it shows high pressure, definitely not leaked out. I then thought it might be a fuse for the compressor; but I don't see that listed anywhere.

In the Buick, the AC compressor is at the top of the engine. I can physically see if the compressor is kicking in. It has high and low pressure valves, right there. On the Caliber I feel lost. I can't see the compressor, I can't tell if it's trying to cycle or not. I think it's down by the front passenger tire compartment. I am told the compressor is always on and has no fused clutch. Is that correct?

I am looking for a guide or steps to diagnose why it is not seeming to come on. I have the Service Manual, but it is over my head and offers no "Start Here" flow chart that I can follow. I am a good old-school mechanic; but I really need your help.

I appreciate your help and I will reply.
 

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From the manual page 24-54, it says:

Both the manual temperature control (MTC) heating-A/C system and the heater-only system are blend-air type systems. In a blend-air system, a blend-air door controls the amount of conditioned air that is allowed to flow through, or around, the heater core. The temperature control determines the discharge air temperature by operating the blend door cable, which moves the blend-air door. This design allows almost immediate control of output air temperature.

So you could have a compressor that is not turning and compressing, or a blend door that is not positioning itself to bring in AC air. It is easier to see if the compressor clutch is coming in first, even though it is hard to find, I would start there.

It may be possible to see if the tubes going in and out of the compressor are a different temperature, if so the compressor is doing something, and you might investigate the blend-door control they break easily, but are way up in under the dash and are horrible to replace.
 

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The 5SE12C A/C compressor is a variable displacement compressor (VDC) which is driven by the engine through a drive hub (1) and pulley (2). This A/C compressor does not require the use of an electromagnetic clutch, as the compressor uses an integral control solenoid (3) to reduce or increase the stroke of the five pistons (4) within the compressor by automatically adjusting the angle of the swashplate (5).

So it isn't like what us old guys are used to (I'm 77) the compressor is always turning, but the pistons inside are modulated to make it compress or not.

The A/C compressor is controlled by the powertrain control module (PCM) or engine control module (ECM), depending on engine application. The PCM/ECM calculates compressor displacement required by A/C system load and demand by monitoring vehicle speed, A/C high side pressure, engine speed, evaporator temperature, accelerator pedal position, ambient temperature and A/C-heater request signals. The PCM/ECM then sends a pulse width modulated (PWM) signal to the A/C compressor control solenoid to increase or decrease refrigerant flow through an orifice located within the compressor housing. The amount of refrigerant allowed to pass through the orifice in the compressor determines the head pressure which controls the angle of the swashplate, which in turn, determines the amount of compressor displacement. When there is no demand for A/C, the swashplate is adjusted to nearly a zero degree angle, which removes compressor torque drag from the engine.

Another thing:
The three bridges (1) located on compressor drive hub (2) are designed to break away in the event of compressor seizure. This action prevents damage to the serpentine accessory drive belt
The drawing in the manual shows a drive pulley made like a three spoke wheel, and describes these spokes could shear, disabling the compressor.
 

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Discussion Starter #5
So you could have a compressor that is not turning and compressing, or a blend door that is not positioning itself to bring in AC air. It is easier to see if the compressor clutch is coming in first, even though it is hard to find, I would start there.
Thank you for replying, you obviously have a depth of knowledge I lack. I apologize, I have read through both posts multiple times, but I need some clarity to overcome my lack of understanding.

I should mention I replaced the blend door actuator assembly a couple years ago when the air would not switch outlets. It is moving at this time; the air will change normally to all outlets. The air can be warmed to full heat and will cool back to the incoming / air circulating temperature. I replaced the serpentine belt in late fall when it broke. It had been making a screeching noise that would go away after a several seconds (if I remember correctly). I do not know if that was compressor related, we didn't try any AC after I replaced the belt in November. The new belt is much quieter, but Kate says she gets a short squeal sound occasionally on starting.

I do not know what you mean when you advise me to "see if the compressor clutch is coming in". I thought there was no clutch action to be observed? I know where the compressor is and I can remove the wheel and shrouds if it will help. Please advise me how to identify what I am looking for to verify compressor action. I will reply and hopefully be able to help my daughter.

Thanks again, I look forward to your reply.
 

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You are right, there is no compressor clutch, I didn't realize this until I read the service manual. BTW I am no expert, I just fix everything myself for cost and convenience.

I had a serpentine belt that would squeal like this on my 96 Chevy van. It was due to pulley misalignment, and caused the flat side of the belt to skid across the surface by 1/8" as it went around the fan pulley. It never hurt anything but was annoying. I ended up spacing the crankshaft driven pulley out 1/8" . This is something that should have never made it out of the GM engine design group...

However, it might indicate low tension on the belt, but it sounds like you would have looked into that too.

The AC compressor pulley is made to "break away" when it gets overloaded. Since you have added Freon, it is possible this could have happened. In my first post, I show page 24-131 from the Caliber service manual, showing the break-away points. It is such an unusual concept that I had to read it a few times to believe it. The manual goes on to show how to replace it if this is the case. I have never had to try to view this, but I can imagine it is difficult, perhaps an inspection mirror would help. I hope you can determine this without running it.

The manual warns not to run the engine without Freon, as the compressor will get destroyed, presumably from lack of lubrication, so don't let all the Freon out as part of your test.
If you find the breakpoints have sheared, I will read and copy more of the manual for you.

If it has not sheared then maybe there is a fault in the system that positions the swashplate that makes it compress when needed, more reading, more copying from the manual, so get back to me and I will pursue this for you.
 

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Discussion Starter #7
Thanks again for you help in trying to figure this out. Here is a summary of all I have gone over; I am pretty much back at square 1.

1: The fan operates properly at all speeds.
2: The air vent selector cable works; air comes out properly at all dash & floor openings.
3: The temperature control knob (a manual blend system - not digital) works properly, the air heats up and cools down; except no AC.
4: The serpentine belt is turning correctly. From under the car, the compressor is clearly turning.
5: The AC compressor is not cycling, there is no cooling.
6: Pressure on AC gauge hose to supply valve shows high pressure; normally would drop if the compressor were cycling.

I am still trying to find out where I go from here. I need guidance to make any more progress.

Thanks for all replies.
 

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I hate to ask you this, but is the center hub of the compressor pulley turning? Although I have never seen it, the manual says there is a break-away action between the hub and the pulley it is on. The pulley would still run true, because it has its own set of bearings. Here is a difficult to follow video, at the end you see the broken pulley on the old compressor, side-by-side with the new one.

Dodge Caliber AC Compressor - Bing video

Hope that helps.
 

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Hoping to hear how you are doing on this. Your promise of response is what motivated me to try and help, and my access to the factory manual is what made me think I could be of assistance.
 

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Discussion Starter #10
I was hoping to shoot a short phone video, but I didn't get home soon enough. In the linked video, the compressor on the left has no pulley or anything to rotate. Kate's compressor looks normal as it spins, it just doesn't put out cold air. I sort of duplicated this post on two similar Caliber forums. No one seems to have any clue how to tell what has failed or how to test a Dodge compressor. Two guys have basically said just buy a replacement compressor & put it on. On a Buick that would require also replacing the evaporator and the drier, plus evacuating all the air to refill the system. Neither of the guys touched on anything, other than a basic get a new compressor. So I am still stuck. Thanks for the interest, I am still searching.
 

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The Hyundai manual stated the breakaway bits in the compressor pulley are to insure the serpentine belt doesn't get ruined, so I would guess that the pulley stays in place after this happens, and would appear to be running normally.

I have replaced a few compressors, and only about half of them got new driers, I think that is a little but overrated. In many cases the drier is so cheap that you might as well replace it, because it collects a lot of junk you don't want to circulate through the new compressor. But in a few of my cases it was impossible to remove the compressor without twisting some of the lines, such as the last one I did, my Wife's 2000 Hyundai, so I just completed the job with the old drier in place. I felt safe, because the failure was the clutch coil, which was not replaceable at the back yard DIY level. It worked fine.

The main thing is to not leave the system open for very long, like a couple hours, and to have a way of pumping down the system to remove all the air and moisture. Harbor Freight has a great vacuum pump that I use. The next important thing is to accurately replace all the lost oil, some components claim they come with proper oil in them, but I have poured it out into a measuring cup, and they didn't come near. Some oil may stay in the system, so you have to look up ways to guess at the amount needed, I have been lucky. Too much could wreck the compressor if it caused a hydraulic lock, too little could wreck the pump too. That is probably another good reason to replace the dryer, because that is where most of the oil stays and reduces the guesswork.

Buying the pump is cheaper than having it done (by a few pennies), and leaves you with a nice addition to your tool box.

Make sure you get the right oil, I could reference the manual for you if you are going this far.
 

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Addition to my (above) response, "replace the evaporator"? I am not sure about that, but there are two components to the evaporator; the "orifice" and the heat exchanger in the people compartment. I have replaced the orifice on my Son-in-Law' GMC van and that was cheap and easy, but the heat exchanger part - no way, it is too buried in the HVAC system. I can't imagine anything getting past the orifice from a damaged compressor, so I think I would leave that part alone.
A neat thing with S-I-L's GMC van, the new orifice was an optional type that modulates its restriction, according to flow to achieve the best drop in temperature at all times. That really worked well.
 

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Discussion Starter #13
I am not opposed to replacing the compressor and other parts; I just have no way to confirm what parts are bad. I'm not a part changer, I would be more than upset if I spent hundreds on parts and found out it was a cheap, simple fix. Or worse, do all the work and it doesn't help. So I appreciate your help, but I am flummoxed at the lack of response by regular Dodge owners & mechanics. In another Caliber forum I alluded to, about 115 people have viewed my post without a single response.

So, to further speculate with your assistance, if you'd like, comment on some possible choices. My home AC also needs service, so I am considering buying an AC vacuum pump. I have switched from HF to Amazon for lower to mid-end tools because there are many more choices. If I look carefully I usually find a model with way longer than a 90 day warranty.

I like the overall price of these two kits. They don't specify warranty, but they are returnable within the 30 days if not satisfied. The more expensive kit also has a leak detector; which if it works could be really helpful. Please look at these and give me your opinion. By the way, Amazon's search function sucks big time. If you try to change to order of the listings from "Featured" to any other order it screws up the list horribly, eliminating lots of choices. What I find works best is like this: AV Vacuum Pump (search), then I would select the best department, like tools or ac. Then I select free shipping to narrow the pool; lastly I click "4 Stars and Up" to aim for the good stuff.



In terms of parts, how would you choose what to buy? Compressors go from $160 re-manufactured to $475, most at least $250. Here is an interesting ad on Amazon that claims to be just about everything you could need except a possible condenser or the evaporator coils. Can you look at this ad and tell me what the part is that looks like long tubing & hoses? Again, I have no idea what parts the car needs.


Like you said, I don't even know if I can get at all the parts.

Don't feel you have to put a lot of time in on my behalf. I appreciate the input, but I still only have the symptoms; the root disease is unknown.
 

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As far as fixing the car, it is hard to lay out a whole repair plan without knowing exactly what is broken. So I think you need to do more investigation before you buy a lot of stuff. Once you reach the point that you open the system, now you need the Vacuum pump.

So a test you can do before crossing this point is to remove the serpentine belt and feel the way the pulley turns to see if you can determine if the compressor "feels" normal.

Like a doctor diagnosing a problem, the more skill and experience you have, the better you can pinpoint the problem before invasive steps are taken. However it takes a lot of fixing, part changing, etc to get to this level, so it is hard to just suddenly be at this level. I am not, but I am confident that if you change enough parts you could be at that level for this particular problem. The value in that is minimal if this is not your normal profession.

I also would like to know exactly what the problem is before buying parts, tearing into the system, etc, but with AC, I find that it is not too easy. The pros get paid big money to do this, but I bet a lot of money gets spent in the learning process. To be able to advance to that level without investment seems difficult.

I believe it will cost you more to change your first compressor because of the price of the vacuum pump, than to have a dealer fix it. To me, it is worth it for many reasons, you will have to weigh that for yourself. My experiences with other people fixing my stuff is usually expensive and unpleasant, this is not the case with many of my family and friends, at least from their point of view. Sometimes I just have to bite my lip and not say anything, so that they can go on without feeling bad about their experience. In all cases it is more efficient for them to cover the cost by working in their own profession and that is is easier on them in the long run. You and I, however, will be more difficult to satisfy with a repair done by others, because we know too much about the details.

To summarize, I would check how the compressor "feels" when rotating it, if you can make an educated guess that it is bad, then spend the minimum to replace it with a HF pump, a rebuilt compressor, no drier, evaporator or anything else unless you suspect shrapnel has been produced by a destroyed pump. If you can't "feel" anything wrong (wish I knew what that felt like) then fully investigate to find the right repair shop that will fix it without any regrets. You are already too knowledgeable about what the repair should be like to be easily satisfied with the "run of the mlll" repair shop, and that is a hard cross to bear, sometimes beer helps.
 
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