I got bored and decided to tear apart an AC compressor just for the heck of it. This is the newer generation V5 compressors from the ~90+ish engines 3.4DOHC etc. Just thought people might find it interesting. Clutch assy off:
The housing open
Heres this little wobbling plate dealy, not sure how yet but it spins and pushes down on the piece below it, pushing and pulling the pistons
Apparently this is what happens when you rev the engine to 7k with the clutch locked on and no lines on the back of the compressor. This and the gernaded bearings you see all around in all the pics
Heres the actual workings of the compressor, it has 5 pistons attatched to a wheel that wobbles to push them up and down.
You can see the valve plate at the bottom left. Its a flat plate with holes in it sandwiched between 2 thinner flexible plates, which bend to allow the valving action, the top is the exaust, the bottom the intake
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11:17 PM
PFF
System Bot
Jun 5th, 2005
The Funkmaster Member
Posts: 1541 From: Chilliwack, B.C., Canada Registered: Oct 2004
Very cool. Still don't know *how* it works precisely, I always had a hard time with those weird a/c gasses/fluids, but thats real cool anyhow... Thanks!
Hm cool. V5 = 5 cylinders eh? Isn't the V5 one of those nifty variable stroke AC compressors? I know the DA6/HR6 compressors cycle the clutch to keep the pressure where it's supposed to be, but I read somewhere that the V5 actually changes its compression stroke to keep pressure in check. Looking at those pictures, I could see how it does it - the "wobbly plate" thing can be made to "wobble" more or less to change how much the pistons move, therefore changing pumping capacity as needed. That's pretty slick.
Yes... V5 and V7 are variable displacement units. DA/H/HR 6 is a fixed displacement clutch slapper.
V and the older series units are similar in operation EXCEPT that the V series has a pressure valve/device that adjusts the pitch of the swash plate that drives the pistons.
The variable displacement feature means that you do not have to cycle the clutch to control line pressure. These units won't cause the surging often felt with older compressors especially on smaller engines. The V units also use less engine HP when they are running since they are rarely running at full displacement.
To run correctly... V series units must have the right control valve for the refrigerant used. Many people get away with dropping R134 on a V configured for R12 but to get the best cooling from the system the control valve needs to be changed to the one for R134. This is required for the same reason you have to adjust the clutch cycle switch on the fixed units... The R134 runs properly at different pressures than R12.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurasic Park)
I'm in the AC biz.. and feel this overpowering need to explain basic refrigeration theory. But I won't! Simply put, refrigerants (freon the most common) compress into liquid and expand into gas. the compressor improves on this and the refrigerant expands picking up heat, when compressed gives up heat. The evaporator and condensor are the exhange to the air that is being cooled and heated inside and outside the car/room/freezer/refrigerator/and.. don't forget the Keg cooler!
------------------ Denise, SE PA Black 86 SE, Jasper 2.8, 5spd iszsu (Carlise 1st place winner stock highmile notchback 2yrs! ) 86 SE stock 2.8, Ttop, 4spd muncie, restored, Yellow
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02:32 PM
LoW_KeY Member
Posts: 8081 From: Hastings, MI Registered: Oct 2001
Lol it just dawned on me that the carnage inside the compressor might have had something to do with all the problems I had keeping the belt on, I thought it was allignment. Im still not sure how it got locked on, especialy since now I cant get it to turn on lol. Prolly a bad relay
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04:02 PM
jscott1 Member
Posts: 21676 From: Houston, TX , USA Registered: Dec 2001
I'm in the AC biz.. and feel this overpowering need to explain basic refrigeration theory.
I wish someone in the biz would design a system sized for south Texas. Car a/c is barely adaquate for Houston Climate. Not just crappy old Fiero systems, I'm talking about new cars. And don't tell me about how they test them in Arizona...that's a dry heat. When I get in my car at work and it's 100F and 90% RH outside and 140F inside the car it's just miserable. I'm halfway home before it's comfortable inside the car. And this is a new car.
Then you take a 17 year old system and convert it to R134a it's hopeless. What I want is a car that has liquid nitrogen circulating thoughout the body and snow coming out of the vents.
if you have sunroof or Ttops the glass acts like a magnafier i know that! I have the shade for my black car.. need to make em for my T-top car i guess.
If you have a sunroof or T tops get a couple of the vinyl cling on sheets you see on the side of many cars to protect kids from sun. I have two on my sunroof and they make a huge difference but I can still see up thru them. (I have Axiom brand and they have lasted several years now. I leave them up there year round.) These sheets don't interfere with opening removing or storing the panel(s).
You also want one of the highly reflective winshield screens. I have one of those opnes made like Bubble Wrap. It keeps the sun off most of the interior. Combinded with the shades on the Sunroof, the car stays far cooler when parked and thus takes far less time to cool off when you spin up the AC.
On AC performance and Conversion...
Proper conversions are actually allot of work. R134 is not a drop in no matter what some people claim. Other Refrigerants that claim to be drop in are often illegal for use in Motor Vehicle systems.
The fixed displacement systems will require changes to work right. So will the V5 or V7 based systems.
Even when you don't convert an old fixed displacement system, using a Variable Orifice is supposed to help R12 performance as much as it helps R134. (Some old fixed displacement compressors ARE NOT compatible with R134 and should not be converted unless you plan on also upgrading the compressor along with the other required changes.)
When you convert a V series you must change the displacment control in the compressor or the system will not work right, especially in high demand environments.
On the dead compressor.... When you spin a compressor with no plumbing and oil, that sort of thing will happen.
Assuming the clutch bearing didn't fail and jam, the only way it could turn on the magnet is if there is some sort of control failure. The pressure switches should have kept the compressor in freewheel no matter what the AC controls are doing. A failed clutch relay is a possibility. A bad ECM or shorted wiring could also energize the relay.
Apparently this is what happens when you rev the engine to 7k with the clutch locked on and no lines on the back of the compressor. This and the gernaded bearings you see all around in all the pics
Apparently this is what happens when you rev the engine to 7k with the clutch locked on and no lines on the back of the compressor. This and the gernaded bearings you see all around in all the pics
Well hell, at least if you were going to trash it, you did it right!
not sure what models.
