Gen 1 AC Refrigerant Refill Tips

Getting back to this ...

OK, if the fans were actually working all along, then it seems like we're back to the few questions identified earlier:

1. The cooling seems weak or spotty
2. The car is 17 years old, by which point the compressor clutch is almost certainly worn beyond spec. It is also possible to be low on refrigerant by this age (some cars will be, some won't).
3. The A/C control won't go into check mode when commanded
4. The HTR 3 fuse appears to be blown.

I think my advice at this point would be to take up questions 1 to 3 with any decent friendly local A/C shoppe. They can easily check your refrigerant charge and top off if that is appropriate. They will have the right tools, including a refrigerant scale, because the Prius's correct charge is determined by weight (100 grams more refrigerant added past the disappearance of sight glass bubbles, under specified conditions). Beware that the specified conditions do not include 105°F; at that ambient temp, some bubbles may be normal, throwing off the procedure. Maybe they can get you an early morning appointment when it's not that hot. If it is low, they also have ways of finding a leak.

You can let them know that (whetever they've heard) you do not need the special ND-11 oil needed for later Prii; in fact, it's wrong for your car. The later Prii have high-voltage electric compressors, you do not. Ordinary ND-8 oil is fine for you. The techs don't need to worry about letting the magic smoke out.

As you'll be there anyway, you should ask them to at least measure the clutch travel and give you the number. You probably don't own a dial indicator yourself, but they do, and it's a very quick measurement when you have the tool. It's possible you'll have to ask for this, and they might not be familiar with the procedure, because so many techs these days only think of compressors and clutches as disposable, which is silly. You can show them the procedure in #31.

If they give you a number that's within 0.35 to 0.65 mm (0.014 to 0.026 inch), that'll be a clean bill of health for the clutch (but very unlikely at 17 years). If it comes back over 0.65 mm, you'll know to start saving pennies for that horrible one dollar, ten minute adjustment job. You could even have them do it for you then and there.

If the number comes back crazy small, like way under 0.35 mm (I've seen this happen!), it can mean the clutch is actually so worn that the plate is too far from the magnet and not pulling all the way in. They can give it a little finger nudge and it'll go CLACK! and pull in the rest of the way, and then the dial indicator will show the right reading (which will be way larger than spec).

Finally, it would be worthwhile to get their take on issue 3: show them the instructions for getting into the A/C check mode, and see what sense they can make of what's going on. If it really can't go into check mode, the ECU may be bad, or some of the control inputs; that could mean that some other HVAC functions won't work right either, and the shop can run through them all and see.

You can ask them about #4 also. It sounds like you don't have a meter to easily confirm that fuse is blown. They will have one, and they can. If it isn't blown, then #4 is a non-issue and you're done. If it is blown, then it's important to find out why it blew, but you could have them do that any time between now and when it gets cold enough to want the supplemental heat.

If it's blown, make sure nobody puts a new 50 amp fuse in there before figuring out what blew it.

 

She can get a freeby multimeter that's "good enough" free at Harbor Freight. If you install their app, there're all sorts of wonderful e-coupons.

 

Well yeah, none of this stuff is expensive. A Harbor Freight dial indicator set is no more than $20, and she'd have it around for all kinds of future brake work and such, as well as for clutch checking. A refrigerant scale isn't an arm and a leg either. And it seems she can get the repair manual cheap on CD if she's serious about more DIY.

I'm just thinking that, pragmatically, for this particular issue, that's a list of several different things that she could easily have but doesn't yet, and there's a certain amount of hassle involved in shopping for them, and at some point it saves time and hassle to just visit a place that has the tools already and the experience using them, and move on to life's next project.

 

If you have to, replacing the clutch is not hard. The key is you do not have to replace the pulley as that's steel and doesn't really wear. The clutch plate is what wears and if I recall it was a simple take out the bolt pull off the old clutch put on the new one, put in bolt, be happy. Don't need to replace the magnet either, it's probably ok.

The symptom of it slipping was that the AC light on the AC switch would come on, then after a bit start blinking (that's the fault).

 

Well this is good news. I’m not getting any blinking, which I’ve notated previously.

I’ve ordered a relay for this item which I understand to operate the AC clutch just to be sure, an extra fuse or two. Plan to recharge the AC soon.

 

There is virtually never any need to replace any part of the clutch whatsoever (other than the adjustment shims, which is what they're there for).

An exception is if the pulley bearing becomes noisy. That's part of the clutch, so if it goes bad, that would be about the one convincing reason to ever replace the clutch.

Otherwise, wear of the clutch plate is compensated by buying the one dollar adjustment shim kit from Toyota, measuring how far the plate moves, taking the plate off (one bolt), removing the old shim(s), selecting the right shim(s) to put back, and re-installing the plate (one bolt).

This will typically be needed every 100,000 to 200,000 miles or so, and you can save the shims you didn't use the first time so you don't spend another dollar when you do it again at 400,000 or 600,000 miles.

If you ever do replace any more of the clutch than that, replacing only the plate or only the pulley is not a great idea. If you ever look at old ones, you'll see they wear in a peculiar way, sort of alternating concentric grooves. As long as you keep the same two parts and simply adjust the shims when needed, they always fit perfectly, because the two parts wore each other into that pattern. But if you ever change only one of the two, now the new part is flat and the old part is grooved, and you only get fractional contact.

That wear pattern also explains why a dial indicator is the right instrument to measure the travel of the clutch. With brand new parts, you could also use a feeler gauge. But after the parts are used and have the typical wear pattern, feeler gauge is no good. Dial indicator will directly indicate exactly what you need to know.

If Sandy doesn't have a dial indicator or the personal interest in making this quick measurement, I would still recommend a visit to a shop that has the tool and will do it. Instructions are already available at #61.

 

The clutch is very difficult to get too, and I don’t have tools here to do any measurements.
I appreciate all your helpful comments.

 

Brian, I purchased what I thought was a standard AC pressure manifold gauge on Amazon. I’m attaching the photos. I went to check the pressure on my 2002 Prius and it appears the low and high side pressure has a threaded inlet. The manifold gauge I acquired doesn’t have a male threaded end. It will not attach to the inlets.

These extra fittings were also included in the package but there’s nothing about them in the product description or instructions.
https://smile.amazon.com/gp/aw/d/B07411T9NG?psc=1&ref=ppx_pop_mob_b_asin_title


Does the AC inlet on the Prius require a special adapter? What am I missing here?? The manifold gauge does not just snap on like I observe in several Youtube videos.

 

You need a quick connect kind of stuff to attached to one of the ends of the hoses going to the L side.

PS: do you know how to know what the required pressures are on both H and L ports of the AC system?
@ChapmanF might be of help here.

 

Yes, I’m ready to do this, I believe I have the how-to under control, with pure R134a in hand. Just need the right connectors. My user manual doesn’t give me any of this level of detail and I don’t have a service manual.

Is that a 1/4” connector for the low side?
What does the high side take?

 

Looks to me like the manifold kit you got is missing parts. Amazon shows red and blue adapters in the picture of the kit. The blue is the low side adapter and is the one you'll use to put R134a in. The red one is High side, and I never suggest that a newbie mess with this connection. I have a manifold, vac. pump, and all that stuff, it's way more than I need. I mostly use a kit that is functionally like this one:

The trigger valve on mine holds refrigerant gas really well, so that the contents of the can don't leak away. Basically for putting R134a into your car this is all you need.

 

Brian,
There are additional parts, see the attached uploaded photos here. I got it all attached.

The Amazon product you posted contains additives, so it would not be appropriate for a generation 1 Prius. I have been unable to find pure 134a in a canister of this type by your own advice.

I’ve got them attached, I was able to check low side pressure and it was a bit low. I was able to fill it to about 55 on regular idle. The trouble I’m having at this point is the right side does not appear to be registering any pressure, O, nada, when I open up the right side valve. I checked it before filling and afterwards.

Still no AC cold air blowing, but the fan works great.

I replaced the AC Relay with a new one and the car seemed to not like it and it threw a P3106 code. I put the old relay back in, cleared the code, and it’s fine. I do note that my car does go into hybrid mode while the AC system is on with recirculate and MAX on. I’m using a FasLink OBDII device which I suspect isn’t very reliable.

Any more thoughts here?

 

I appreciate that everybody has comfort levels, and it's important to know what your own comfort levels are. I respect that.

For the record—more for any future readers of the thread—you get to the clutch by turning the steering all the way to the right, then taking out 2 or 3 screws that hold up a floppy plastic cover. Again, I'm not here to change your judgment of your own comfort zone, but just to make sure any future reader gets enough info to decide if it's in or out of his or her comfort zone.

If it's out of your comfort zone, heck, that's why shops exist. At a total of about 15 minutes for a competent shop to complete the measurement and the adjustment if the measurement calls for it, it's the kind of thing that won't cost any more than the shop's minimum billing increment. Not great at a shop that bills only whole hours, but if you find one that bills by quarter hours or so, that's all it should end up costing.

While it's totally appropriate to know your comfort zone and what tools you may or may not have, that isn't a way of deciding where the problem will or won't turn out to be. The old story about the guy hunting for his keys under the streetlight because the light's better there than where he dropped them is pretty much a parable about that.

P3106 is a code for the HV ECU not being able to communicate with the engine ECU. There's no AC relay involved there. Are you sure the relay you replaced was the one you thought it was? What was the reason for replacing it?

Well, it might be starting to look like you have a good appetite for a lot of kinds of DIY, and that's awesome, but maybe your own boundaries on your comfort zone just don't reach as far as the level of attention-to-detail that leads to successful air conditioning work. There's nothing wrong with that, and no shame in going to a shop to let them do stuff that they're geeky about and you're not. If it's possible you'll end up there eventually, maybe it might as well be soon, so you're not spending more of your own money and time on equipment they've already got and tasks they already can do.

 

Ok, I realized I may not have properly hooked up the high side AC port with these adapters to allow access. They need to be turned clockwise to open up the valve for a proper test, counter-clockwise to seal and pop-off, some of the YouTube how-to videos I saw missed that step so I didn’t get that.

Chapman, I’m not at my regular residence, I’m in an HOA community which prevents us from working on our vehicles so I’m not so keen on getting underneath the car here in 100 degree heat and angering the neighbors. I could be fined and I don’t have my tools. However, your instructions are encouraging. I’d be inclined to sort out the clutch when I return to Long Beach but I’m not there and won’t be for a couple of weeks. I’m quite patient, determined to resolve this with help, and don’t mind getting at it myself. I’m very curious and appreciate resolving things myself and am confident it will get fixed. My motto is....I can always take it to a repair shop. I’m an avid DIY’er in life — there’s much satisfaction in accomplishing your own tasks.

The relay I replaced runs the AC clutch, just thought I would check it. Interestingly, it’s the same relay part number above it. I previously swapped the two just for kicks to see if that might help my AC issue, and it threw my hybrid system into Triangle death mode. The Prius did not like the same relay. So I put them right back, and everything was normal again,

I changed out the 50amp #3 heater fuse today.

Later on I’ll retest the pressure to see what’s really going on and proceed from there.

 

P3106 is a code for the HV ECU not being able to communicate with the engine ECU. There's no AC relay involved there. Are you sure the relay you replaced was the one you thought it was? What was the reason for replacing it?

I cleared the code and could not get it to trip again.
I need a good OBDII scanner. Can you recommend one that you know in fact reads out codes on the Prius?

 

Good heavens. Did you find out why the old one blew first? If not, please stop reading this until you have removed that fuse again, until the reason it blew has been found and fixed.

Patient, determined, and confident are all good things, but 'reckless' is also a thing.

Most of the ink on PriusChat goes to an old beater laptop running Techstream with one of the available J2534 dongles that are a lot less money than the Toyota-endorsed Drew Technologies one. I've been quite happy with my Tactrix dongle, I've seen good reports about the VCX Nano, and just about everybody and their dog has a mini VCI (counterfeit of the original XHorse product by that name), which are dirt cheap, but sometimes flake out doing some things.

 

Hey Brian! What is the name of the oil you use normally in your vac pump, when you're vacuuming your AC system?
I have a UVP1.5-220, 2 stage vacuum pump motor:1/4H.P, 1.5CFM

 

The system on a gen 1 is very conventional. Any R134a that can be used in a non hybrid can be used in your car. I mostly posted the pic to show the gas adder that I use/suggest. Makes adding refrigerant really easy. THe mechanism is the important part, not the actual can of freon.

 

I have no idea. I've had my pump for about 20 years and never changed the oil. It continues to work as advertised. You might want to check at an old line, non chain autoparts store.

 

The manifold gauge set I previously purchased on Amazon for about $30 pictured above on these posts with the connectors would not allow me to adjust the actuators to get a reading on the low side and high side when connected so I returned them. I purchased an improved Yellow Jacket model 41209 direct from the supplier which was $20 savings over Amazon which I understand is built to last longer and a set of Robinair R134a couplers elsewhere (photos attached here). I’m awaiting their arrival.

The only thing I see here is the fittings don’t easily connect up to the supply lines so I will yet need another adapter to connect supply line to the couplers.