2001 Prius - A/C light blinks

Nice thread - and timely for us, as this just occurred for the first time in my daughter's 2001, affectionately known around here by several names, including "Bluey Fuse". Our AC flashing light also appeared directly on the heels of a simple LOF service and a 'courtesy safety check' of the car at the local Toyota dealership - they gave the car an A+ report card, no issues, and the flashing AC showed up four hours later. Odd, that.

Chap - As you appear to be the font of all knowledge for these First Gen Prius models, I'd appreciate your take on things. I personally suspect a slipping drive belt based on a visual inspection only, but I'll give your code hack a run. What codes should I be keyed on?

We have a Gen II Prius, too - and codes there can be reached on the touch screen. No go for that diagnostic path on the Gen 1?

 

Right, you don't get the codes on the touch screen in Gen 1, you get them by counting blinks of the A/C light when you put it in test mode - there are a bunch of threads here with the steps. It seems to forget codes quickly, so the best results seem to be with asking for the codes right after it signals a problem. Maybe there are still some times you don't get codes; other people keep posting "my A/C stopped working and no codes, no codes."

If you suspect slippage, you can check the belt, but I would definitely measure the clutch gap ... your car is certainly old enough to be worn there, and it's an even easier cheaper fix than replacing the belt.

Often, a slipping belt will make a hideous squealing noise.

Any codes you read you can post here, or look up in the service manual volume 1.

-Chap

 

I was at the dealer to pick something up, and I had them take a physical look at things - and the diagnosis was a failing A/C compressor clutch, with a total estimate of $818 to replace the clutch, the relay, evacuate and recharge the system. Just after leaving the light flashed again, and I was able to catch the code this time: 21. From a quick search that seems to be related to the light issue, so a false reading of some sort (and I did this while parked with the car outside in bright sunlight). Ideas?

 

So, what did they think the problem was, the clutch, the relay, or the refrigerant charge?? Amazing, somebody must have a boat payment due.

It would be perfectly reasonable for you to check the clutch. Measure how far the plate pulls in, it's supposed to be 0.35 to 0.65 mm, if it's much bigger than that it's probably slipping. That costs a buck to fix, it's covered in a bunch of threads here.

I wouldn't ever replace the whole clutch for that unless there was evidence the whole clutch needed replacement. The only other clutch part that can wear out is the pulley bearing. There have been a couple recent posts about that, so if you're feeling cautious, stick a mechanic's stethoscope on it with the engine running and see how it sounds. (While you're at it you can touch the water pump and idler pulley bearings too; I recently did that on mine and they all sounded ok except the idler is getting loud). Or, while you're checking out the clutch, loosen and slip off the belt and give the pulley a spin by hand. If it isn't quiet and smooth, or it sounded bad in the stethoscope, then you might elect to replace the whole clutch instead of only adjusting it. That should be $200 - $300.

Anybody who thinks you need to evacuate and recharge the system to replace the clutch needs to pay you for putting up with BS.

About your codes, yes, there is one for the solar sensor (21 sounds right, but I don't keep them memorized, it's better to look in the manual) and it's normal to get that one whenever light isn't shining on the sensor under the windshield (or something is covering the sensor). If you think it should have seen light then maybe you do have a problem there, but it wouldn't be your main problem, and maybe you just didn't catch the code for the main thing. If it cut out and blinked the A/C light, you are probably in the right neighborhood if you're checking the belt condition and especially the clutch gap.

-Chap

 

all! I still see a code 21, when testing the A/C in my PI. The original belt is still installed. By inspection, it seems to be ok. No sqeakin‘ sound or anything like that.
Can you provide a picture and/or drawing on how to inspect the compressor clutch? I have no idea, where to look, really.
When starting the cold engine, I hear the compressor to cut in. But I am not sure about this, after the engine has warmed up.

 

Look, I realize I don't really know what I am talking about, so if I am totally off-base here, just ignore me.

But, I had the ac light flash in my Camry and it turned out to be a simple "replace $13 relay" in the fuse box. Probably not applicable here, but just thought I would throw it out -- now you can throw me out....

Also Found this, which I do not understand in the least...which mentions something else. Good luck!

2001 Toyota Prius Blinking A/C Light: Air Conditioning Problem ...

 

No problem ... people at all levels on PriusChat.

Now, if you're interested in how to grow on that dimension, the next idea is to pay attention to the trouble code that was reported in the post you were replying to. There are lots of different issues that can make the light blink; you don't know which one it's blinking for until you read the code(s). The A/C codes in a Prius are super easy to read, you don't need any kind of special tool; a quick search on PriusChat turns up lots of threads that echo the instructions from the repair manual on how to do it.

So drbojo posted about getting code 21. Now if getting the most reliable information in the shortest time is important to you, the best place to look up such codes is the repair manual on techinfo.toyota.com, but you can often do almost as well with a Google search on the PriusChat site, as long as you understand you will, often pull up posts with mixed up or wrong information so you're on your own to figure out what information you can and can't rely on.

For code 21 that situation isn't too bad. Pretty much all the posts on PriusChat you would find in that search all agree that it means low light is detected by the solar sensor, and that it is a normal code to have any time you check codes at night, or in shade, or at any time there isn't sunlight shining right on the sensor. Code 21 doesn't mean you have any problem at all, unless it doesn't go away even in direct sunlight.

Right, code 21 would never mean that.

Annnnd, it would never mean that either, but that makes a really good example of how far off in the weeds you can send yourself by just blindly searching the internet without starting with what codes you've got. That post was from somebody who (a) was troubleshooting a different code (one about clutch slippage) and (b) was in the really rare situation where the code didn't straight up mean what it said, but there was a problem in the sensor that detects the slippage. (So it's also an example of another risk when just searching random internet posts, sometimes posts about really unlikely explanations come up ahead of the likely ones. If you're getting a clutch-slip code, almost every time it is going to mean your clutch is slipping. Can it ever mean there's something wrong with the sensor circuit? Sure, yeah, there's that post you found, and one other case I've seen on PriusChat, where a collision had cut the wires to the sensor. But those are the coin-lands-on-edge cases. In general, whatever trouble code you get, you start by looking for exactly what the code is telling you to look for. You don't start thinking you've won the lottery for weird until you've checked carefully for the obvious cause and you're really sure that's not it.

In drbojo's case, if no code is showing up other than 21, and it goes away in the sun, and the A/C is otherwise working and drbojo just pulled codes out of curiosity and wondered what the 21 meant, the A/C is probably fine.

-Chap

 

Chap:

Thanks for the detailed response!

I appreciate the tips.

Right now I am gearing up to load the Mini-VCI software on an old laptop and then try to figure out how to use that (I bought a few weeks ago off EBay) -- and then try to pull the code that my Prius threw a few weeks ago....Just a generic "check engine," that disappeared after a couple of days, so I do not expect anything too wild.

Again, thanks,
steve

 

Ever think of checking the AC clutch relay? This was a common issue with the 2000-2002 Camrys and was a $7.00 fix - some kind soul found a non-Toyota relay that worked like a charm.

 

Not only do people think of checking the clutch relay, you're the second person to suggest it in this very thread, which hasn't had any activity for a year except drbojo's questions about a code 21, which is a solar sensor code and nothing to do with the clutch.

Now, for the benefit of any future reader who is actually getting a clutch code, sure, it makes sense to check the relay. You have to check the clutch travel anyway and the easiest way to check is to pull the clutch relay and put a remote-start switch across the socket terminals, then rest a dial indicator on the clutch face and watch how far it pulls in when the remote-start switch is pushed. So in the course of doing that, you would naturally be looking at the relay anyway.

However, that's still not the most likely case. If you are getting the clutch code on a high mileage Gen 1, the most likely explanation really is plain old wear of the clutch. When you measure the travel it will come out higher than the 0.65 mm maximum, and you'll fix it with the shim kit that costs about a buck (even less than the relay!) and ten minutes of your time.

But once again, just for the record, drbojo is getting a code 21, which is a solar sensor code, not a clutch code. (It is also a normal code to get when sun is not shining on the sensor, so it isn't even a sign of any problem at all, unless the code is still there in direct sunlight.)

-Chap

 

I had no code and decided to tackle replacing the clutch. Thanks to your posts, turned out to be a very easy fix.
$198 plus ship. Im retired and having a lift in garage does help
Thanks for your input and help
Don Maw

 

Glad to hear it! What did you find that swayed you to replace the whole clutch instead of just reshimming it?

-Chap

 

Hello, Chap. Thank you for the careful explanation on these boards of how to fix the problem with the clutch. I've found it very helpful in educating myself, and appreciate the detailed explanation and the tutorial. I own a low mileage (108,000) 2001 Gen 1 Prius.

Today I tried to get codes,. Not much sun. I shined an LED flashlight onto the solar sensor from outside, positioning it on the windhshield. After following the procedure in Stationtostation's post what I got for codes was ... 2 Blinks, Followed by a Pause and Then a single Blink. So .... Blink Blink ... Pause ... Blink ... .and then the pattern repeated.

The situation with the car last summer was:

· The A/C light would blink and the air would stop blowing cold.
· Turning the A/C off and on would sometimes bring back the cold air. The hotter and more humid it was the harder it was to do.
· You could hear something which sounded like it was spinning or turning off, which I guess may have been the clutch.
· This was most noteable in hot weather as it could blow cold in cooler temperatures.
· The A/C was recharged and pressure tested and the pressure checked out.
Freon was put at the right level.
· The relays were changed, first with a regular relay ,then with Toyota factory relays. The first guy who took one of them out had a hard time because they were stuck, and he broke one but got it out.

The car continued to have the same problem even after these $300 worth of fixes at a mechanic and Toyota.

This year, anticipating the hot weather, I tried to find a mechanic to fix the issue. I explained what is listed above. Four shops all were encouraging me to change the compressor. One shop tried to diagnose. They hooked it up to what looked like a fairly robust scan tool. Later they told me that although the freon was bit low, they did not find leaks, and that they recommended compressor change. They quoted me $655 for a new Denso compressor, $330 Used, and wanted $390 for labor (including recharge). They also told me the Serp belt was cracked (it is, but i am fairly certain it wasn't a few months ago, or last summer).

I found the new Denso for $360 online, but got it local for $446 after tax. I picked up a serp belt for $20. receiver drier filter ($15).

I found another shop willing to put in my compressor for $360. So the cost parts and labor would be: $840.

I am concerned about having them do it because they say I don't need to change the receiver drier, and while they seem honest and relatively competent, I wonder how much they really understand about this repair. I think they may just stick in the new compressor, recharge, and not check other things. I did print out your article and brought it to them, but I don't know if they read it. And they say the labor is more to fix the clutch than put in the new compressor.

One other shop that I went to is supposed to do a diagnostic on Monday for $50. I brought your article (and my desc. of the prob.) to the mechanic who I know, and even showed him the new Denso and explained the issue. He too thinks putting in the new compressor is better than the clutch fix, although he wants to do a diagnostic before fixing anything.

My concern is that I'll have someone put in the new compressor but that it won't fix the problem. I'm also concerned I might be dealing with an electrical issue, for example, something coming from the wiring harness. And it seems no one is telling me the whole story.

Although it may not be related, one strange thing about my vehicle is that the locks on the driver side door and the three others don't seem to operate in unison. It has made me wonder about a short somewhere. (i.e. when you lock the front passenger side door, only 3 locks lock, not the driver side). The fob stopped working long ago.

So far I haven't gotten a lot of help in figuring this out, and your comments have been the most useful

Some questions I have are:

1) If I replace the compressor and it doesn't fix the problem what do i do next?
2) Is it riskier/safer to put in a used compressor and spend less, or a new compressor to try to rule out any parts problem?
3) Could my problem be in the wiring harness? If so, is there a way to know this before I put in the new compressor?
4) How does a mechanic check if the problem is in the Temp Sensor? Amplifier?
5) I've read that on the Gen 2 the AC compressor getting cut off intermittently is a symptom of a failed inverter pump? Could that be an issue for me? Could I have a problem with the hybrid system? (at one point when the mechanic changed the relay I did get a weird exclamation point kind of code and message on the vehicles' screen, but he got that to go away.)
6) Does the receiver drier have to be changed when you change the compressor? Is it just the filter? Or the body as well?
7) Does the orifice tube need to be changed? Expansion valve?
8) How many hours does it take to put in a new compressor and serp belt and recharge? What is a reasonable labor rate?
9 Can I recharge myself using one of those cans from the auto parts store?
10) What can I say to the mechanic that may be helpful in helping him find the root of the problem?

I would like to keep the vehicle, but if this is going to reach a couple thousand dollars to fix the A/C, then it could make the car too costly to keep, as it needs some other mechanical repairs and I might be better off getting something else, rather than paying thousands to hunt down an A/C issue.

I don't have tools to fix it myself, and it seems difficult to find a mechanic who will do the fix you suggest. Should I keep looking for mechanics? No one seems to know how to do this, nor seems to want to unless it is big money. I've talked to about 5 different ones so far.

Thanks again for all the insights, and the help!

 

Oh my gosh, Nat, did I just read through that 1,100 word post and see that nowhere in that entire story has the clutch travel been checked?

The clutch is mechanical. It wears. The travel gets larger than the 0.35 to 0.65 millimeters it's supposed to be. Eventually (when it gets to be 2 to 3 times that!) it starts slipping. That's fixed with a one dollar shim kit from Toyota and about ten minutes of time. You can easily do it yourself. Every behavior you have described is the exact behavior you'd see with that issue, and yet it looks like no mechanic you've talked to has ever checked it.

Could something else be the problem? Sure ... other possibilities could be checked, if the clutch travel is checked and proves to be within spec (unlikely for a 2001, unless you've hardly ever used the A/C), or the one dollar clutch adjustment is made, and some problem still persists. But again, those are coin-lands-on-edge cases. If you see a 2001 where the A/C cuts out, bet on clutch wear. After winning that bet, bet the same way on the next one, and the next one, and the next. It's the winning bet.

Now, if you insist on having the replacement compressor put in, because you've bought it and all, the good news is, it will probably solve the clutch slipping, just because it comes with a new clutch on it. (You did get one with a clutch on it, right? There's a pulley on the front?)

So, chances are very good it will solve the problem. It's just that solving the problem that way instead of spending ten minutes and a buck is like having all your teeth pulled and replaced with dental implants because there was a little piece of broccoli between two of them, and nobody suggested a toothpick.

Here's a post that describes the adjustment process, in case that helps.

-Chap

Edit: by the way, I suspect the failure of the driver's door to unlock electrically only means that lock motor has worn out. I had to replace mine somewhere around the fourteenth year; those things just wear out too. There are threads on PC about replacing it. You can find them on eBay for a fraction of the dealer cost, but many of those are quality-control rejects from the supplier, so if you go with an eBay one, look for the thread that describes how to test them on the bench before going to the trouble of opening the door up.

As for the fob not working ... have you changed the battery in the fob?

It doesn't sound like you have a car that's falling apart ... it sounds like you have maybe three trivial issues.

 

Thanks, Chap. I appreciate it. I think you're right, and if I had the tools, I would do it to find out for sure. No one else has been willing to. I did buy the Denso with a clutch. I can return it for 30 days. Should I ask them to change the receiver drier if they put in the new compressor? Or anything else?

 

Goodness gracious, man, shim the clutch first, before you run out of your 30 days to send the compressor back! If the clutch adjustment doesn't solve it, you'll still have the compressor. If it does, return that puppy, unused, and get your $400 back.

Borrow the tools if you have to. Or borrow a friend who has the tools.

-Chap

 

Hello, Chap. Hope this note finds you well. Today I got a photo of the clutch. https://priuschat.com/media/ac-clutch-rusted.16783/full

Also a video of it moving (but I can't figure out yet how to load that to the site). It looks pretty rusted. And I was wondering if you thought that the shim would still work or if replacement might be better given the condition?

It's 82 degrees here and sure enough it failed intermittently! But getting closer! And thanks for the great articles and help. Nathan

 

Hard to see much detail in a picture of a spinning clutch. But does it have holes rusted through it or something? The color of the clutch doesn't affect its function.

Is the clutch bearing noisy? That's about the only thing that could warrant clutch replacement. If you don't have an automotive stethoscope, you can just put one end of a long screwdriver or the like on the front of the compressor near the clutch, and press your ear to the other end. (Most comfortable when you use the pointy end on the compressor.) Careful not to let it catch in spinning belt. Listen whether it makes a reasonable whirr or a horrifying scraping rumble. The A/C doesn't have to be on (the clutch bearing is in the pulley part, always spinning whenever the engine runs.)

If the bearing sounds shot, that could be an argument for replacing the entire clutch instead of just readjusting it with the shim kit. That requires more tools and more time than the simple wrench and ten minutes to do the adjustment.

But even a clutch replacement is way less invasive than a needless compressor replacement (which will call for refrigerant evacuation, doing the work, oil and drier replacement, air evacuation, and refrigerant recharge, and presents you with a smorgasbord of opportunities for failure).

Again, it pretty much seems like your clutch slips. The clutch slips when it has worn and needs adjustment. Adjust it.

-Chap

 

I'm having the same problem in my 2003 Prius, although it doesn't even have to be an insanely hot of a day or a steep hill involved (This morning it's in the low 80s, 60% humidity FYI). The a/c starts working but pretty quickly turns off, and the green light blinks. This happened last summer, too, but rarely (and it was mid-pandemic, so I barely drove the car anywhere!), and now it happens every time I'm driving.
I checked the code myself, but it did not give me a 2-digit code. Lights blinked 4 times (no pause), followed by steady fast blinking that did not stop. Any ideas? I don't know how/where to look up what the code numbers even mean.

 

The steady fast blink means it had no codes for you at that moment.

The blink-the-code mode that you entered also includes a check mode, where different things happen when you twist the "temperature" knob to different positions. Checking the compressor requires the car to be in READY (not just ON).

So, you can do that by:

• start with the car OFF, blower switch OFF.
• make the car READY (like starting it normally).
• within 5 seconds, press A/C button three times, then turn blower switch to Auto.
• wait for the four slow blinks.
• note any blinked codes (or that there aren't any, if it's just a fast blink).
• twist the "temperature" knob all the way to the left.
• under the hood, the compressor clutch should click. Watch the lights for any new codes to get blinked.

If a 22 gets blinked then, that would indicate a compressor clutch issue, which is what I suspect anyway. Has that clutch ever been adjusted before in the life of your 2003? It's 18 years old now, and it simply gets worn. The adjustment kit costs about a buck, it's about ten minutes' worth of work; maybe triple that for someone who's never done it before.

If you get some other code, or still no code, then report back what you get, and whatever you observed the compressor doing, and maybe something else is going on, but for now my money is on the simple clutch adjustment.