Station's AutoBlog: Gen 1 Prius A/C Clutch Diagnostics and Replacement Hello, This is a instructional guide for diagnosing and replacing the A/C clutch for a Gen 1 Toyota Prius. (2001-2003) Does your a/c light blink and no longer blows cold in your Prius? Is the problem intermittent and difficult to explain to a Toyota service rep? Here is how you can determine what the issue is and if this guide can help you... The test car is my boss's 2002 Toyota Prius Gen 1. He complains that after driving sometimes that the a/c will shut off and the a/c light will blink. He resets it by turning the a/c off and then back on again to fix it. Step 1: Diagnostics To be sure you are having the common issue everyone else is having we first need to "catch" the problem in action by putting the car in "diagnostic mode" NOTE: This test should be done in open daylight or a flashlight needs to be flashed onto the solar sensor on the dash of the car.(photo coming soon) If this is not done, a false code will be shown. Do these steps in order in about 5 seconds. 1. With the car OFF, turn the AC fan knob to OFF. 2. Turn the car to ON position DO NOT START THE CAR YET 3. Press the A/C button 3 times. 4. Turn the A/C fan knob from OFF to AUTO. If you have done this correctly, the A/C and MAX buttons will blink together a few times. Followed by the A/C light blinking every half second. You are now in AC Diagnostic Mode. **For this guide we are looking for a "code 22" which will be 2 solid blinks followed by a pause.** BLINK_BLINK______BLINK_BLINK______BLINK_BLINK____BLINK_BLINK______ **If you get a "code 21", then you need to get into more sunlight or use a flashlight on the solar sensor. The solar sensor is shaded and is very likely NOT malfunctioning.** So what is a code 22? Code 22 suggests that there is a problem with the A/C Amplifier circuit OR that the the compressor is spinning at 500 RPMs LESS than the crank or more. So what does that mean? It means The clutch and/or belt is slipping on the a/c compressor. Now we need to recreate the error code to confirm. There is actually a definite way to do this. 5. While in Diagnostic Mode AND the A/C is OFF you will need to accelerate,in a safe area such as an on ramp, until the engine is at a high RPM. While the engine is revving high, quickly turn on the A/C. 6. Repeat until you have the trouble code blinking. It should blink twice<pause>twice<pause>. What we are trying to do is put a heavy load on the A/C to make it slip. The clutch should be able to engage while accelerating like this. If it does not, then the clutch or belt is worn out. You may have actually noticed your A/C cutting off after accelerating hard onto an interstate or while passing someone. Or it can be any random time when the engine may be idling high and the clutch cannot grab ahold soon enough. So if you have a "Code 22" you will need to proceed to step 2. I recommend checking your belt first. If it is torn you need to replace is first. Normal wear may or may not cause the Code 22. If it is the belt, you may also have overheating issues on the engine, however if you only have issues with the A/C continue ahead. Step 2: Dis-assembly and Inspection Tools you will need: 21mm lug wrench or factory supplied lug wrench in spare tool bag in trunk 10mm 12mm Ratchet and 1 foot extension or multiple smaller ones 14mm wrench 15mm socket 2-Claw Puller (available for rent at any auto parts store) C-Clip Pliers (also available at any auto parts store) Brake Parts cleaner Lock-tight (optional, but recommended) Flathead screwdriver Tools that help a lot: Impact Driver (not the same as Impact GUN, we want LOW torque if we have to) Swivel head for socket Rubber mallet Parts you will need: (at minimum) Serpentine belt - Part numbers vary from manufacturer. Pick one up at your local auto store. Item 5-Clutch Assembly Toyota Part #88410-47030 Item 9-Shim kit/Gasket Kit Toyota Part #88335-14020 Parts can be found HERE I would also recommend picking up ITEMS 6,7,9. They are really cheap and should you lose or break any of those parts it will be nice to have them there as the car is apart... don't want to be stranded... You should ALSO pickup a new serpentine belt at this time and be sure to order before you work. Your local store may have to order one. The parts should run you about a total of $220. (+/- Tools you may or may not have. ) HOWEVER, the alternative to replacing the clutch is the compressor. Which from the dealer ran upwards $700 + in parts alone. You would need special A/C tools and a new dryer,evaporator, and R134.... Considering all this.. $220 and about an hour and a half of your time... might be worth it to you... 1. Jack the passenger side of the car up and remove the wheel from the car. 2. Remove undercarriage covering the A/C compressor. (Found behind the brakes to the back right side.) It is held in by seven 10mm screws. 3. Remove the coolant overflow reservoir. It can be kind of tight, but it should just pull up and out. (picture coming soon) 4. Locate and loosen the 14mm tensioner locking nut. It is the top pulley to the right of the coolant overflow. It is easiest to use a wrench. Do not remove the nut, only loosen it.5. Locate the belt tensioner bolt. Loosen this bolt and push down on the pulley attached to it until the serpentine belt can be removed. Inspect the belt for cracks, worn grooves, or any abnormal wear. Replace if it is torn, if not, do not reinstall yet and continue ahead. 6. Remove the 10mm holding the clutch pressure plate. Be careful as you remove this part. There is a tiny washer behind the pressure plate that you need to REUSE. Sorry I did not get a picture of this it seems. 7. Use your C-Ring pliers to remove the C-Clip holding the pulley on the shaft. 8. You now need to attack the puller to the pulley. Put the 15mm socket, bolt side in and tighten the threaded rod to the back to the socket. It helps to have a extra set of hands to hold the puller while the other tightens it.*Note I used a 15mm socket. You may need to find a similar socket that fits. You want the socket to be deep enough to go to the compressor housing and not damage the shaft in the center. 9. Disconnect the black, two-wire plug going to the magnet. 10. Remove the C-Clip holding the magnet to the shaft and remove the magnet. You may or may not need to persuade the magnet to come off. I used a mallet... As you can see, the clutch has worn so deep that it had developed large grooves.Compared to the new clutch...Step 3: Reassembly and Function Test 1. Using brake parts cleaner and a rag (I used a diaper) clean the oil off of the pressure plate and the pulley. DO NOT GET BRAKE PARTS CLEANER ON OR AROUND THE ORANGE SEAL. IT IS A BEARING AND IT WILL SEIZE! SPRAY ONTO RAG! The parts come shipped with a small coat of oil to keep the parts from rusting. Compressor<--Magnet<--Clip<--Pulley<--Clip<--Shims<--Pressure plate<--Bolt 2. Reinstall the magnet and C-clip in reverse order. (sorry I did not take any more pics of this as it would only look the same on camera) Do not forget to plug the magnet electrical harness back in! TIP: If you cannot get the C-clip to set, be sure to push magnet in as far as you can and use a flat-head screwdriver to carefully knock the clip into the grooves. 3. Reinstall pulley and C-Clip. 4. Put the bolt into the clutch pressure plate. Reuse the old shim washer plus the 3 new shims and slide them onto the bolt. You want the shims to be behind the pressure plate,on the bolt, and against the shaft on the compressor. The reason we shim the clutch is so that the clutch is not always engaged on the pulley. The shims space the pressure plate away from the pulley, so that the only way to engage the A/C is to pull it in with the magnet. (when you turn the A/C on it will turn on the magnet and pull the clutch to the pulley) 5. Reinstall the 10mm bolt. Holding down the pressure plate, tighten the bolt. Be sure not to over tighten it. German torque spec, Gudentyte. (Unfortunately I was unable to find the proper torque specs... otherwise I would MAKE you do it that way) *To make sure you are properly shimmed, spin the PULLEY. It should spin freely and the pressure plate SHOULD NOT SPIN.* If both the plate and pulley spin, you will need to shim the plate out some more. I used all three shims and it worked just fine. I do not believe you will need more than that. 6. Reinstall serpentine belt. 7. Tighten tensioner with 12mm. Be sure not to over tighten the belt. You want SOME slack in the belt, not tension. 8. Tighten the 14mm locknut. 9. Reinstall the coolant overflow by sliding the back side onto the bracket. 10. Reinstall the splash guard. 11. Reinstall the wheel. Do the same test you did earlier and you should never lose you A/C again. Well... it wont be because of the clutch anyway... It's too hot outside... Fix this... - William You're welcome... Now give the Gen I Prius section a better forum.
well done, we need more like this for the DIY and customers to be better informed. Keep up the good work.
Wow, what a great info share/write up. Especially for the Gen I guys (like me). I've done a post like this b4 so I can appreciate how much time and effort went into it. I've said it b4 n I'll say it again, the Prius is better supported online than the Ford Mustang. The Mustang has been dethroned!!!!!!! Thanks Station2Station
What a great write-up, Station2Station! It deserves the final polishing touch with the last few details you'll find in the service manual (either paperbound or on tis.toyota.com): You already recommended buying the C-clips and shims (items 6,7,9) just in case of breakage, but more than that, Toyota calls the C-clips nonreusable, so to be fully by-the-book you would always install the new ones. If the pressure plate is stubborn coming off, there's a special tool for it. From the diagram it looks like the center of the plate is threaded (for a larger diameter bolt than the one holding it to the shaft), so if the pressure plate won't pull off easily, you can just thread the correct-size larger bolt through and turn clockwise to drive the pressure plate off. If you look at the inner edge of the C-clips, both are beveled on one side. On installation, the beveled side has to be facing away from the compressor (out toward the wheel well). In other words, the clip's flat side always goes against the part (magnet or pulley) the clip is meant to hold in place. The "German torque spec gudentyte" is 13.2 newton-meters (9 or 10 foot-pounds), no more. That's not super-tight; it would be easy to overdo it. You really want to select the shim or shims that give you a pressure plate clearance of half a mm (plus or minus 0.15 mm). You don't want the clutch dragging when disengaged, but you don't want it slipping when engaged either (after all, that's why we're doing all this!). The idea is to clamp a dial gauge to a solid fixed point on the engine or compressor, with the point resting on the outer face of the pressure plate. Then apply 12 volts to the magnet coil. You want the dial gauge reading to change by 0.5 mm ideally. If the change is < 0.35 mm go with more shim, if > 0.65 mm then less shim. If you have a belt tension gauge then you want 110 pounds (plus or minus 11) if the belt is brand new. 67 pounds (plus or minus 10) if it's got more than 5 minutes of run time. Torque for that 14 mm tensioner pulley center lock nut is 40 newton-meters (30 foot-pounds) once you've got the belt tension right. Those are the only extra points I know of. Thanks for a really detailed write-up! -Chap
I searched EVERYWHERE FOR THE FSM O_O I have a MASSIVE collection on FSM's for all kinds of cars. I usually just modify other peoples cars for fun. Did JDM motor swaps and what not when I was a Sophmore in High School. Thank for you the info Chap, it is very appreciated! This is all excellent and important! It so ended up the magnet wasn't really tight. A good pull or another run with the puller would have sufficed. The specialty tool was hard to find without having to order one and I happen to have pullers on me. Torque specs. O_O Thank you! Yeah, it came off really easily so I only snugged it on for sure... The rest I tightened as I felt appropriate I researched everywhere on the shims. They were VERY VERY VERY thin and only came in one size. What I actually had done is assembled it trying all three washers. (1, then 2, etc.) Three was the magic number (as supplied) the other 2 would drag, yes. I then tested A/C on and off while driving. I need to get a belt tension gauge as I replace them constantly. 110lbs vs 65lbs sounds like an awful lot....
