2001 Prius - A/C light blinks

This makes sense; I am surprised that the turtle light did not come on.

 

The green light within the A/C button? If I recall correctly, the manual says that light will blink if the A/C compressor isn't spinning at the speed the ECU expects. The ECU knows the engine RPM and the compressor RPM (there's a sensor), and the two speeds should be what you'd expect from the relative pulley sizes. If the compressor RPMs are lower than that, the ECU decides the belt (or magnetic clutch?) is slipping, and blinks the light.

I think the ECU also does normally disengage the A/C when you're asking for strong acceleration, but I haven't noticed it blinking the light for that. You might want to check the belt tension.

You can get the diagnostic code out of the A/C ECU without any special tools. IIRC the dance is: IG ON (with fan switch set to off), push A/C 3 times, turn fan switch to auto. Then count the blinks of the lights. Steady fast blinking means no diagnostics. Otherwise you get a 2 digit code like "blink blink blink (pause) blink blink" for 32. There can be more than one code, and the whole sequence will repeat in case you don't copy one down the first time (which means you know you've seen the whole sequence as soon as you see the first code repeated).

-Chap

p.s. one of the diagnostic codes is for the solar sensor, and you will always get that one if you activate the diagnostic mode when it's dark out. Don't pay it any mind unless you also get it in sunlight.

 

My best guess is it was too much for the AC to handle, so it shut off. Our AC compressor in a 2001 slowly died. It started with blinking once in a while on really hot days... shut off the AC, turn it back on two minutes later and it was fine.

Then it became more frequent. Now it will even occasionally happen in the winter with the defog on.

 

Hi Nikfish,

Are you saying you still have the 2001 and this still happens?

Why not read off the trouble codes (can be done without any special tool, see above for how) and post them here?

There's a variety of possible explanations other than "compressor died." Some could be easy to fix.

-Chap

 

when the a/c light blinks the a/c compressor shut off for some reason, for me this happened when my a/c compressor seized due to a tiny oil leak from a crash. This also happens if the clutch does not engage for the a/c compressor. This could be for a variety of reasons, the magnetic thing doesnt pull the clutch in, or the line pressure is low.

i would suggest u turn on the car and turn on the a/c and listen to the compressor as it "clicks" on if it sounds loud or grinding kinda, its due to the lack of refrigerant oil

 

BTW I had the blinking green ac light in my '02. I tried the diagnostic test mentioned in these posts with nothing from that. Knew system was charged with no strange noises. Finally took it in (wife wouldn't drive in the heat) for diagnostic at dealer. Ended being (not the sensor as I had been thinking but) the compressor clutch - pricey part and labor. Total of $1000.

 

I can't imagine ever wanting to do that unless you absolutely know the compressor has failed. It's a highly invasive job. At the very least, you have the compressor itself, which is fairly pricey. You have to evacuate and reclaim the old refrigerant. In addition to the compressor itself you have to replace the drier. (I haven't rechecked the book to see if the drier's available separately or combined with something else, the way the condenser's combined with the radiator.) If you're doing the job because the compressor really did fail, you've got failure debris all through the system and need at least a flushing rig and chemicals to clean it out, and maybe replacement of other components. (And if you're not doing it because the compressor failed, why are you doing it?) Then you need to put it all back together, hold it at deep vacuum with a pump rated in microns (check prices on those babies!) long enough to boil out moisture, and then you can stick in your can of 134a.

If you're getting the code 22, you might be looking at a ten-minute, $1.21 fix with a shim kit, or at worst a replacement of the compressor clutch which is maybe ~ $200 and doesn't involve opening the system. See here. Don't even do that much if you don't know what code you're getting. Pull the code! For the A/C you don't even need any kind of scantool to read it.

Cheers,
-Chap

 

Depending on how much you want to spend you can do it for less than $500 including the price of the compressor and having a shop refill it with refrigerant (which I would recommend for a compressor replacement). *This is what I would do and not what a reputable shop would do.*

On ebay search (2001 prius ac compressor remanufactured), they start at about $135 with shipping, search (2001 prius ac o rings) about $15. Use a small pointed tool, like an awl, and push down on the schrader valves to release any pressure in the system. Make sure everything is clean around the lines at the connection points before disconnecting. With clean dry hands remove the old compressor and reinstall the reman with new o-rings at the connection points. Put it back together and take it to the ac shop.

If it's just out of refrigerant you might want to add the pound you have lying around in order to see if the compressor is the problem first. Then if it leaks slowly out again you may want to buy anorher can with dye in it and then replace the o-rings where you see the dy leaking. If it leaks rapidly you will probably find the problem clearly unless it is under the dash, at which point I wouldn't bothere with the compressor.

You may find the ac experts on this forum balking at my suggestion here but I've done it and it worked and has saved alot of money.

Good luck

 

What was the outcome of this issue guys?


iPhone ?

 

This thread wasn't about 'an issue', it was about five different issues for five different PC members starting seven years ago. They all had a similar symptom (not cold enough, A/C light blinks), some because of the clutch, some because of a leak, some in the aftermath of a crash. Only one person in this seven-year thread reported even bothering to read the codes from the system, even though that requires no tools, no special scanner, and takes less than a minute to do. The one person who tried didn't succeed in getting the codes, didn't come to PriusChat to ask why or seek help, and ended up spending $1000 for the replacement of a clutch you can buy for $200 that is not that hard to replace, though there's a good chance it needed nothing more than the shim kit for a measly buck and ten minutes of easy work.

Others went further and changed out the whole compressor, much more invasive and requiring evac and recharge, and to be fair maybe that's what some of them needed.

The moral of the thread is, as long as you've got money to burn, never, ever, bother to find out what problem you're having before you start throwing parts at it.

-Chap

 

Hi Chap,

Thanks for the info. The A/C light in my 01 Prius is sporadically blinking with the A/C no longer blowing cold air. Turning the A/C off and then back on solves the problem for various lengths of time. This just started when it got very hot. I ran the diagnostic test several times in the sunlight and it is not displaying a code. Do you have a recommendation for next steps? Thanks!

 

I'm kind of puzzled by several reports now of people seeing the A/C disengage and blink the light (meaning it definitely knows there's a problem), but not give any code when asked for codes. Some people do get the codes, and I don't know if it comes down to doing the code query soon enough after the problem was signalled? I don't know how long the HVAC controller retains the codes ... it seems to forget them faster than I'd want it to.

You didn't say exactly, but did you try pulling over to do a code query right after it had blinked a problem, or only later when you got where you were going?

Two easy checks if you can't get codes:

First needs no tools at all, just start the car, blower on high, A/C and MAX and RECIRC all on, temp knob all the way to the left, what do you see in the sight glass (located in the liquid line, narrow aluminum tube near the driver side headlight)?

Second, some basic tools (just to drop the right-side, passenger end of the engine under-cover), plus a dial indicator with a magnet base, and a way of switching power to the A/C clutch.

The way I do it uses a "remote start button" tool I've had for years, nothing but a big fist-sized button with a long zip cord and two alligator clips. Pull the "CLR MG" relay out of the "engine room junction box", stick two tab terminals (or similar metal bits) into the two wide slots (3 and 5) of the socket, alligator clip the start-button tool to those. Now, with the car key ON (not READY, only ON), you should be able to click the compressor clutch in and out with just your thumb on this button.

Clamp your dial indicator base to something metal and stationary near the compressor pulley, and set it so the indicator tip rests on the clutch pressure plate and measures how far the clutch pulls in when you click the button. It should be one half (0.5) mm. Anywhere between 0.35 and 0.65 mm is ok. Yours might be worn to a much bigger distance than that, in which case you've got a likely culprit (which will cost you one dollar to fix).

Note: if you were checking a brand new clutch, an alternative to the dial indicator would be a simple feeler gauge you could stick between the pressure plate and pulley. But your clutch isn't new and the wear pattern is never flat, so the feeler gauge will give you a false reading on a used one, where the dial indicator won't fail. There are pretty reasonable ones at Harbor Freight, etc.

-Chap

 

Chap,

I haven't checked the diagnostics directly after it starts blinking. I'll do this next and see if anything comes up.

If the distance the clutch pulls is greater than .65mm, what would be the dollar fix?

Thanks!

 

1. Order the 88335-14020 shim kit. It cost me $1.21 a couple years ago, but recently I've seen it at online dealers for an even buck.
2. Undo the center bolt and slide your pressure plate off. Be careful not to lose the shim(s) already behind it. It/they might come away with the pressure plate, down in the recess where it sits on the shaft, and have to be picked out.
3. Measure the total thickness of old shim(s) you took out.
4. Add 0.5 mm.
5. Subtract the exact measurement you just made of the clutch travel.
6. This is the shim thickness you want. Find a combination of shims that you have that will add up to as near as you can get to this thickness. The three you got in the kit are 0.1, 0.3, and 0.5 mm thick. You want to get within 0.15 mm either side of the target. Usually there will be two combinations that would work, one on the tighter side and one on the looser.
7. Put that combination of shims behind the pressure plate and reassemble.

I recommend trying the tighter combination first, but then start the engine and watch what happens when the clutch is disengaged. It should be fully disengaged and not getting dragged around at all. If it drags a bit, reassemble with the looser shim combo. After running that way for a while, the friction faces may fit each other better, allowing you to go back to the tighter shim combo with no drag. That will give you the most capacity for wear before it all has to be done again around your 400,000 mile service or so.

-Chap

 

Osiris12, I'm on my 5th Gen I Prius, maybe we should request a fleet discount...

Elder Gen I Prii A/C clutches are prone to slippage (and subsequent blinking A/C LED) due to (a) worn serpentine belt and (b) buildup of rust/debris between plates of the magnetic clutch.

So first: replace the serpentine belt. A new serpentine belt is less than $20 at most auto parts stores. Toyota wants $100 to replace it.

Requires removal of passenger front tire, removal of inner plastic splash shroud, and maybe 90 minutes in the driveway.

Secondly: partial disassemble the A/C magnetic clutch and clean the plates with isopropyl alcohol on a cloth (or more enthusiastically, with a bronze wire brush and Dremel tool) using procedure described in the instructions from THIS link:

Station's AutoBlog: Gen 1 Prius A/C Clutch Diagnostics and Replacement

This blogger describes a replacement procedure; I happen to disagree that the "grooves" in the clutch plate are wear marks. They looked machined to me, so I cleaned my clutch and EGADS! my previously intermittant A/C now works gangbusters!

ChapmanF recommends measure and set the factory spec clutch plate spacing; doing what the factory says is usually a good idea.... a new set of spacers is less than $10 but you need a micrometer to tell the spacers apart . He discusses it earlier in this thread...

If you are satisfied that the serpentine belt is NOT slipping and the clutch plates are clean and giving good mechanical connection, then it's time to suspect either the compressor itself or something else in the A/C system.

But read the linked blog entry in any case. It's an excellent DIY project.

 

No need to take off the passenger tire—just steer to the right, plenty of access to the compressor.

The groove business is a distraction, if you're looking at it thinking "oh, it's got grooves, but maybe the original had grooves, so it isn't worn, right?"

There's an excellent photo of a new pressure plate in station2station's blog post already linked. Scroll down to the big one that shows the old and new parts side by side. The new pressure plate is in the lower right corner. You can see that it is divided into two separate friction surfaces, with a gap between them that maybe you're calling a "groove", but except for that they are machined absolutely flat. And that's not what the worn one looks like. It never is.

And even though the surfaces wear grooves, you're right in a sense that the grooves don't matter. The two pieces still fit perfectly, because they wore the grooves into each other. The only thing that matters as they wear is the overall distance they have to travel to meet. That gap starts out at one-half millimeter from the factory. By the time it gets to be twice or three times the gap it should have, you're likely to see slippage.

When that happens, you spend ten minutes with the one dollar shim kit, restore the correct gap, and go on to solve other world problems.

BTW, you don't need a micrometer to tell the three shims in the kit apart. They're all thin, yes, but 0.5 mm is still five times as thick as 0.1 mm, right?, and 0.3 mm is right in the middle, and you can feel and see the difference if you know to look for it. I only posted the micrometer photo in reply to another post that did PriusChat readers a disservice by saying they were all one size.

If you don't want to trial-and-error it, you should have a way to measure the old shims that come out with the pressure plate. Your most beat-up cheap caliper is adequate for that.

The one tool that does contribute a lot to success is a dial indicator. The reason is that new (flat!) clutch gap can be measured with a dial indicator or a simple feeler gauge, but on an old clutch the feeler gauge will read false and the dial indicator will always be right. I used to think of dial indicators as expensive, but there are indicators on eBay under $10 and sets with a mounting base around $20, and they'll do everything a DIYer needs for this job and a ton of others around the car (like checking brake rotor runout).

Honestly, I've never checked how much more time you'd get out of a worn clutch by putting in the same effort as to fix the excess gap (pressure plate off, pressure plate back on), but without fixing it, instead putting in more work of solvent washing and/or Dremeling. It's useful to know that did something for you, and it may help another person who is sweating in the boondocks with no access to a shim kit, at least long enough to get to civilization and get one.

But honestly, there's nothing special about the Prius Gen 1 magnetic clutch, such things go back to 1954 Pontiacs. That would be sixty years for your repair idea here to have become widely known and practiced, and I'm not aware that it has. If the gap's too big and it slips, make the gap not too big, and it won't.

-Chap