Gen 1 AC Refrigerant Refill Tips

Another potential indicator of a needed charge - if the A/C doesn't get used very frequently, there can develop leakage around the seals. I have a convertible in which I rarely use the A/C, and I have to remember to run it for about 10 minutes here and there, even if the top is down, just to keep things lubricated.

 

So that’s very interesting. While I do often run it on hot summer So Cal days when I’m out, the AC has never been what it was when the car was new. So there’s that.

Let me ask you this, if it’s not the 5O amp fuse...
Could I simply by an R134a canister with a hose and gauge and check the existing pressure once it’s hooked up and ready to load. I’ve watched one how-to video somewhere and it seems simple enough. I’ve located 3 canisters of R134a on Amazon. I believe this is the correct product, if not I’ll remove the image forthwith. I wouldn’t want anyone acquiring the wrong product for a 2002 Prius.

https://smile.amazon.com/gp/aw/d/B07QKNLQJQ/ref=ox_sc_act_image_1?smid=A1OYBDZNBHG2RG&psc=1

I’ve previously replaced the water pump on this car so I imagine this job is doable....

Thanks for all your help this morning.

 

Yes. Check to make sure that's the correct refrigerant for your model.

You may find that an HVAC shop can check your charge fairly quickly and recharge for not a lot of money. Worth a call.

 

Well, I took the plastic cover off the 50A #36 fuse, and it’s definitely blown.

 

Fuses are cheap enough to replace, but something caused it to blow. I would put in a new one and see if that resolves your problem.

 

You mention dashboard error codes, so that reminds me, have you checked for any HVAC codes yet? I don't think you've mentioned it.

Start with the car OFF and the heater fan switch OFF. Turn the car key to ON (not START, just ON) and, within 5 seconds, press the A/C button 3 times, then turn the fan switch to AUTO.

All the HVAC button lights should blink four times slowly. Then watch the A/C button light for further blinks. If it just does a steady fast blink, it isn't reporting any codes. Otherwise, it will blink out two-digit numbers, like "blink blink (short pause) blink (longer pause)" would be 21. You can write down all the codes you get; when it circles back around to the first one you wrote down, you know you have them all. Whatever you get (codes or just the fast steady blink), you can report here, it'll help.

You'll very likely have at least code 21 if it is at all dark or shady when you do this. That's normal; 21 is for the solar sensor.

As for fuses, there are several involved with the HVAC system. The wiring diagram calls them out by their names (like HTR NO. 3 in your owner's manual picture above), not by the owner's manual numbers like #36. So I'll use the names and ratings.

• 10 amp "HTR" (top right on the instrument panel fuse box, behind the panel you can see with the driver's door open). This is the source to all the controls, and to the relays sourced by the other larger fuses. If this one goes, none of the HVAC system will do anything.
• 50 amp "HTR" (top right in the underhood fuse box on the driver's side). This supplies the fan in the cabin. If this one goes, no air will blow in the cabin.
• 30 amp "HTR 1" and "HTR 2" (both small format 30 amp fuses) and 50 amp "HTR 3" (larger size), all 3 in the underhood fuse box on the passenger side. All three of these are for the supplementary electric heat that comes on in cold weather before the engine is warmed up. Nothing to do with the air conditioning,
• 30 amp "RDI" and 30 amp "CDS FAN" (both in the underhood, driver-side box in the rightmost column, both 30 amp, but RDI is a big 30 amp fuse and CDS is a small one). These supply the two big fans under the hood, needed for the A/C to cool.

From your photo of the "HTR 3" fuse, it is very hard for me to guess if it is blown or not; the glare in the photo is right where I would need to be able to see. Even the cheapest electrical test meter you could find at Home Depot, etc., would let you check it. (Edit: this post crossed with yours saying it's definitely blown.) But it's (edit: still) a red herring anyway, as it's just for the supplemental heat.

Some more observations would be good. Do both of the underhood fans run when you have the A/C turned on? Have you looked at the A/C compressor pulley when the engine is running and the A/C is on, to see if the center portion pulls in and turns along with the pulley when the A/C kicks in? As covered in #14, just eyeballing that won't tell you everything. But every observation helps build the picture.

For a lot of people, observing feels like "not doing something", while changing parts or squirting in refrigerant feels like "doing something". But sometimes the urge for "doing something" gets in the way of identifying the problem.

 

I feel pretty dumb. I don’t know how to get my vehicle in diagnostic mode. There’s nothing in the user manual about it and I can’t seem to find anything in Prius Chat for the Gen 1. While I did find an AC system check re the blinking, nothing happened, but I was not in Diagnose mode.

The clutch seems to be spinning and working fine. I can’t find any any fans inside the engine compartment to ascertain. All the fuses do appear functional on closer examination.

I’ve only relied on the dummy codes on the dashboard and an occasional neighbor with an OBDII device that actual read the Prius for a water pump issue.

I’m perplexed at this point. It doesn’t seem I’ll be able to resolve this myself unless I simply try to fill it with some R134 I guess. I just hate taking it to the dealer or some local shop that just doesn’t understand hybrids. I’m not at my local residence right now.

 

Did you see I gave step-by-step instructions for that in the 2nd, 3rd, 4th paragraphs of #26?

There should be two with big visible white plastic blades right at the front of the engine compartment, right behind the front grille.

Anybody would be perplexed with so little information to go on, but you're in the best position of anybody to get the information that's missing. You could give the blink codes another try, that's easy, and check for the fans spinning again, that's easy. (If they're really not there in the engine compartment, that's a problem! )

If you say the compressor clutch (center portion) does seem to be spinning along (have you made sure you can tell the difference between what it does when the A/C is on and when it's off?), what do you see in the sight glass when it is running? (On Gen 1, the sight glass is over near the driver's side headlight IIRC.)

I understand not wanting to take the car to some unknown local shop, but then, the usual concern is they might do something blindly without being sure what's going on first. On the other hand, it kind of sounds like that's what you're tempted to do yourself, so six of one....

 

Okay. So where am I supposed to be looking for these codes? If it’s on my center console where my usual display is, nothing happens when I go through the procedure outlined in #26. I’ve done this per your instructions. I’ve tried several times. I get no blinking from the AC button, no codes. Nada.

I found a YouTube video on getting the 02 Prius in Diagnostic Mode and mine just won’t go there. It ignores me.

I’ve looked for the fans, I have none on my ‘02. I purchased mine in early 2001, maybe mine was not fitted with them.

Re the clutch, it operates the same with the engine running and with the AC on. No visible differences to my eyes. All the clutch talk above is really beyond me.

While the car was parked I revved the motor as much as I could, and I detected an ever slight hint of faint cool air... I could be imagining things.

It’s still hot here. If I take it to an AC shop and he tells me it’s the clutch, what can I expect to pay for a reasonable repair and recharge???

Many thanks.

 

It depends where you are. Some areas are more pricey than others. If it's the clutch, less than an hour to remove it and shim it properly. A recharge is about $100 where I live, assuming R134A. The older R12 is quite expensive now.

I would call around for quotes on hourly rates and charges to recharge the system. Avoid the dealer, lots of overhead. A good independent shop that does HVAC is probably your best bet.

 

No. You have a Gen 1. The HVAC codes will only be blinked out for you on the A/C button light. Don't look for anything on the display.

Nothing at all? You start with the car off, fan switch off. In a five second period: (1) car key ON, (2) A/C button pressed 3 times, (3) fan switch to AUTO.

Do you get the four slow blinks of all the heat control button lights, but then no blinks on the A/C button? Or not even the four slow blinks?

Do any of the lights on any of your heat/A/C buttons ever light up ever, when you are normally using the car and you press them?

What most people call "Diagnostic Mode" is either a way to get pull up some screens on the center display that are only for troubleshooting the radio and infotainment, or a way to keep the engine from turning off or inhibit the traction control. Since you never include links to the youtube vids you're watching, I can't tell which one you're trying to do, but either way, it's a red herring that won't tell you anything about the heat or A/C.

You definitely have them. They look like this:

When you looked at the clutch, you were looking at the round thing in the lower right of this photo, right? It's taken looking past the passenger side front tire, and has a plastic cover removed so the engine and A/C clutch are visible.



The round thing in the middle is the engine crank pulley, and the one further to the right and down, with the triangular pattern, is the A/C pulley and clutch.

The person who took that photo jacked up the car, removed the passenger front tire, and took the plastic cover completely off, but that was way more work than is needed. It is easy to see the clutch just by parking on a nice clean spot, turning the steering all the way to the right, and taking about three screws out of the plastic cover to let it hang out of the way.

Whenever the engine runs, that pulley on the A/C also turns (because of the belt), but if the A/C is off, the center part you see there, with the triangles, does not turn.

When you turn the A/C on, that center part should make a nice audible clack and start spinning along with the pulley it's part of. When the A/C turns off, it releases again and stops turning, even though the pulley around it still turns.

If he says it's the clutch, there should be no recharge cost: the clutch is completely repairable without opening the system or losing any refrigerant or needing anything recharged.

But it's amazing how few mechanics any more understand that the clutch is adjustable. Many will propose to replace the clutch instead (roughly $200 parts, hour or so labor). Some will even propose to replace the whole compressor just for a clutch issue (insane, several hundred dollars parts, labor quadrupled or so, full evacuation and recharge of the refrigerant necessary).

So the mechanic needs to know that Toyota sells this adjustment kit for about one dollar:



The kit is nothing but three little round shims of different thickness (0.1, 0.3, and 0.5 mm). The actual adjustment is dead simple for any mechanic with basic tools. You might not have a dial indicator yourself, but you can give a mechanic these instructions.

As before, there's no need even to lift the car (in a shop they might, just because they can, but access is easy enough on the ground). Turn the steering all the way to the right, reach past the tire, take a few screws out of the plastic cover so it hangs out of the way and you can see the clutch.

With the car turned only ON (no READY light on the dash!), clamp the dial indicator to something so its plunger rests on the rim of that central round part of the clutch (the part with the triangle shapes, that doesn't always turn, but the plunger shouldn't be on the triangle shapes, only the rim of the round plate).

Pull the "CLR MG" relay out of the underhood fusebox on the driver's side, and get a jumper wire to put between terminals "3" and "5" of the socket where that relay plugs in.

Watch the clutch while bridging and not-bridging those terminals (can do with two people, or one person and long wires). Confirm that the plate pulls inward when the terminals are bridged, and pops back out when they're not.


(The manual shows connecting a battery straight to the terminals on the clutch. I just pull the CLR MG relay in the fuse box and bridge those terminals because it's easier to reach and less grimy, and I don't bend all the ways I used to. Either way works.)

Write down the dial indicator readings both ways, and subtract, to get how far the plate pulled in. Write that down.

If it is between 0.35 mm and 0.65 mm, the clutch is ok. If it is way over 0.65 mm (and whose isn't, on a 17 year old car?), get a wrench the size of the center bolt on that clutch, loosen and remove the bolt, and slide that center plate toward you to remove it. Be sure to catch whatever existing shims were behind it; sometimes they'll stick on the end of the shaft, or sometimes be down in the hole in the plate. Collect them, anyway.

Use a caliper to measure the total thickness of whatever existing shims came out. To that number, add 0.5 mm.

From that result, subtract what the dial indicator told you about how far the plate moved. The number you now have is the thickness of new shims you need.

The shims in the bag from Toyota are 0.1, 0.3, and 0.5 mm thick (they're all tiny, but different enough you can feel which is which). Pick any combination of: no shim, any one of the shims, any two of the shims, or all three of the shims, that add up close to the required thickness you just worked out. It's ok to come out as much as 0.15 mm on either side of it. Usually, you can find two different combinations that qualify, one on the low side, one on the high.

I generally try the combo on the low side first. Put that combo of shims in the hole in the center of the plate, slide it back on the shaft, and put the bolt back in (9 foot pounds). Plug the CLR MG relay back in, start the engine and watch the clutch. You want to see both that it locks in and spins around when the A/C is on, and that it completely releases when the A/C is off and sits perfectly still, not being dragged around at all by the pulley.

If it seems to get dragged a little, turn the car off, undo the bolt and remove the plate again, take out the slightly tight shim combo you put in, and reassemble with the other combo that would be slightly on the loose side. (9 foot pounds on the bolt again.) Confirm that works properly if you want. Put the plastic cover back in place with the few screws you took out.

That's the whole job. One dollar in parts, maybe 30 minutes if they've never done it before. Save whatever shims you don't use, you can use them to make the next correct combination in another 100k or 200k miles.

Now, if the mechanic you go to decides it really is low on refrigerant, that'll be a different, separate estimate.

 

Wow Chapman - What a great post - so much info I am going to print it out

I just added a can of r134a to my wife's 2001 today - instant cold air - don't know if it has a slow leak or not but if this happens again I will come back to this thread

 

Well, Rod(?), some cars will get leaky; if yours benefited from adding refrigerant, then that's the situation for your car, and a future order of business would be finding the leak.

But some cars won't get leaky much. I sold my 2001 at around 23x,000 miles with working A/C and had not added any refrigerant, though I had needed clutch shims around 205,000.

I sold a 1984 Ford last year with the A/C working, but I had done clutch shims once in the time I had it.

That one got the refrigerant topped up once while I owned it, sort of proactively, when I noticed some of the tubes looked very rusty. I got replacements, and had the system recovered so I could replace the tubes and o-rings, then recharged. It used R12, which by then was banned and scarce and expensive, so I found a shop that would weigh what they recovered, then only charge me for the extra top-up amount when they put it back in.

 

Is there a standard procedure for recharging gen2 AC system pls?
Care to share your experiences?

 

Well, this is a thread about Gen 1, in the Gen 1 forum.

There are important differences between the Gen 1 A/C and the later generations. Gen 1 was the only Prius generation with a mechanically driven compressor; all the later ones are electric, don't have clutches to check or adjust, and require a completely different lubricating oil.

So, any discussion of Gen 2 recharge procedures in a Gen 1 thread would have very high risk of confusing later readers of the Gen 1 thread.

It would be perfectly well suited to the Gen 2 forum (and should even already be discussed in a lot of threads there).

 

Sandy that fuse appears to be blown. You can try another, they aren't too expensive, but it may just blow again. I've learned a lot since my previous post on this thread, for one, always listen to Chap. But also, it's a very conventional a/c system. Take it to an a/c shop, or the likes of Midas if changing the fuse doesn't work.

 

Agreed - we have two Priuses - a 2001 and 2002 - my 2002 AC is running strong - just passed 241000 miles - I am going to monitor my wife's - if it leaks then probably need to have a leak test - everything around the AC system appears to be in great shape. So fingers crossed - this high mileage r134a is supposed to have a product that helps seal up the system so we will see

 

Ok, I woke up this morning and started scouring YouTube to identify how AC clutches work to have a better visible understanding. I observed mine last night with the car engine running and with the AC on. It seems to be working just fine as far as spinning but however after watching the YouTube videos I got a better understanding of the clutch mechanism.

Now since I’m up early the ambient temperature is not as hot. The car is also parked with the front end in a bit of shade. I again had an opportunity to observe the clutch in action with both just the engine and then with the AC on. To Mayeye it appears to function in both the same manner. The car simply wants to shut down with the AC on since it is in a park position. The highbred motor just does it. And I am a single person here with no one here to help me keep the motor idling.

I do have fans and they are not working.... why not?

But some good news I suspect. I turned on the recirculating button and the AC and Max. The car is blowing some cool air. Hallelujah. It is definitely somewhat cool. I’m not currently sitting in the car that’s been sitting in the sunlight all day in 105° temperature like I was yesterday.

I put my hands on the AC supply lines while running the AC. The low side is mildly cool while the high side is warm to hot. The ambient temp is now 105.

I also located the AC site gauge this morning, finally. And with the AC running for several minutes it shows me that there are tiny bubbles traveling through the site gauge. I do not observe a clear stream. From my understanding this indicates that the AC Freon is low. The AC system has never been worked on in this car. It is a 17 year old car, and I am the original owner.

Read all the above comments and the AC diagnosis check, I have conducted procedure as indicated. And I do not get any blinking on the AC buttons.

Now, should I go to AutoZone and simply buy a can of Freon 134A and a pressure manifold gauge and get to it?. What do you think now that you’ve got this information? Depending upon the gauge readings, I could proceed.

 

I would do that. Not a lot of investment, and it will likely improve your cooling.

 

Does gen 1 need the special oil (mixed in with AC recharge gas)? If so, get oil-free.

My 2 cents: dealership will do an evacuate, test and recharge for around $150, maybe spring for that.