A/C Woes - Opinons/Guidance Welcomed

[WeeYari]

Have you tested for a signal coming from the pressure switch?

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[06YarisRS]

Originally Posted by WeeYari

Have you tested for a signal coming from the pressure switch?

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I assumed, WeeYari, that since I was getting battery voltage at the compressor connector to trigger the clutch with the A/C switch on an illuminated that everything from an electrical standpoint was ok. With the connector removed, the A/C light will not illuminate. I'll dig deeper into this. Thanks!

Edit: The wiring at least looks the same. I guess I'll look into figuring out how to test that sensor.

[WeeYari]

I think that with a/c on you will always get power to the compressor. It is up to the pressure sensor to send the signal to engage the clutch....I "think"...*shrug*

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[atomic_hoji]

Bah, frustrating! Sorry to hear it hasn't panned out yet man..

Let it sit for a few hours and see how it settles out.. then try your voltage checks again to see if it's asking for the A/C compressor.

edit: No, no epiphany - at least on the 3rd. gen - the ground is hardwired.. BUT - fuse check?! There is a 7.5A fuse supplying the A/C amplifier; looks like fuse panel inside the car.

Cleared codes and everything before trying? Maybe the ECM or A/C amplifier is giving a cutoff because it has the prior code stored of low pressure?

Just throwing some things out there.

-- Adam

[06YarisRS]

Thanks guys! I did some more tests before heading out of town for son's hockey game. Just got back in from the garage and the low and high side are both at 50. When I engage the A/C switch, the rad fan cycles on and off at very high speed about every 20 seconds or so. For a minute it seemed like the engine was going to stall - revs dropped down - under load from the compressor, I suspect - and then it recovered. There was no change in the gauge readings. Also, if I remove the connector from the low side pressure sensor, the fan does not turn on and off as when it is plugged in.

After the charge, I directly connected my jumper cable from the battery to the compressor pins with the engine running. There was no change in the gauges and no drop in idle either.

When I first started introducing refrigerant this morning, the suction pipe became quite encrusted with ice even though I introduced the refrigerant slowly, monitoring the gauges. I thought maybe things froze up.

I will try your recommendations. I am also going to have to try interpreting the diagrams to see if how dependent the compressor is on the other parts of the system. But what gets me is if I apply direct 12V power from the battery, the compressor/clutch seems to do nothing.

I'll keep plugging away.

[tmontague]

So either your compressor is bad again (doubtful) or the way you are jumping it is not a sure guaranteed way to run the compressor (only ewd's would show that)

Or the way you are adding in refrigerant is not working property. Either it's being done wrong or something wrong is going on. Possibly an issue with manifold gauges?

[06YarisRS]

Originally Posted by tmontague

So either your compressor is bad again (doubtful) or the way you are jumping it is not a sure guaranteed way to run the compressor (only ewd's would show that)

Or the way you are adding in refrigerant is not working property. Either it's being done wrong or something wrong is going on. Possibly an issue with manifold gauges?

Thanks Trevor. I'll post in a sec....

BTW, I could not see any differences in the schematics between the 2008 xd and my '06 Yaris.

[06YarisRS]

SUCCESS!!! This may sound weird, but one of the parents of another kid on my son's hockey team suggested gently tapping the pressure sensor port. He said he'd seen it work if for any reason the switch is stuck. I did this a few times. So, it's either that or something equalized as it sat (as Adam suggested) but it's functional now. I put the gauges on my windshield and watched the pressures. At first I was getting around 50 on the low side (supposed to be 22 - 36) and it wanted to spike up about 250 - 275 on the high side (supposed to be 199 - 228 @1500 rpm) - a slight overcharge situation. I let a little R134 out of the low side and it's running around 40 Low side and 210 - 215 high side. I'll let a touch more out tomorrow. I warmed up my garage up as best as I could and then the inside of the car - very toasty in there. Then, I engaged the A/C with recirculation. Air is icy cold. I'll grab a thermometer tomorrow and see what temps I get.

I gotta say, there are a lot of variables with this A/C stuff. As you mentioned, Trevor, the gauges...I questioned them a few times.

I'll also monitor pressures over the next couple weeks to see if the system is completely tight.

[WeeYari]

*clap*

(how many times have I said pressure sensor)

Hope she holds out for you.

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[tmontague]

Originally Posted by WeeYari

*clap*

(how many times have I said pressure sensor)

Hope she holds out for you.

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Ya kudos to you, sometimes its the simple things and you picked that out from the get go.

Good to know about the tapping solution though, may be useful in the future

[06YarisRS]

Originally Posted by WeeYari

*clap*

(how many times have I said pressure sensor)

Hope she holds out for you.

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Yup! It does seem you were right, WeeYari. My apologies for not initially mentioning your suggestion. Though, I wouldn't want to stake my reputation - as questionable as that is - on that being the cure for my particular system. But, other than sitting/time, it does look like the only other manipulated variable in this situation.

I'm fully prepared to have the system slowly discharge. You know it has to happen. The area I'll be watching is the tube connection at the firewall. I remember it going in very snug when I reassembled, but it is the only connection for which I did not install a new o-ring.

I was very happy to see this little high side sensor window nicely full of R134. In my excited state, I forgot to snap a pic of the gauges showing proper pressure. Will post one tomorrow.

If anyone is bored and happens to have a manifold gauge set kicking around, it would be neat to see the readings and a comment on how effectively their system works. I'm guessing the optimal settings - for a stock Yaris would be the numbers I mentioned a post or two back. It would be interesting to know how slight differences in pressure influence the functionality.



Thanks WeeYari!

[tmontague]

I will test put my pressure's down the road and let you know
I have a feeling mine is slightly low on r134, I'll probably top up at the same time. Only problem with mine is at idle ons crazy got day it is not that cold. Still cool bit not nearly as cold as when the car is moving and the revs are up

[06YarisRS]

Originally Posted by tmontague

I will test put my pressure's down the road and let you know
I have a feeling mine is slightly low on r134, I'll probably top up at the same time. Only problem with mine is at idle ons crazy got day it is not that cold. Still cool bit not nearly as cold as when the car is moving and the revs are up

Thanks, I look forward to it.

No doubt your underdrive pulley is affecting that as you mentioned earlier. Practically every car I've owned drops cold air at idle and increased revs and more air through the condensor brings it back to life. Think I'll check out my other Yaris and minvan as well. Gotta make those gauges pay for themselves. LOL.

How much does your A/C affect idle on the 2ZR? Mine seemed to labour slightly, until I removed a bit of the refrigerant. It still slows a few rpm when I engage A/C. I'm getting the impression that A/C systems are more power-robbing than I had initially thought.

[atomic_hoji]

Woo! Nice - glad it's worked out for you. Good call by WeeYari.

-- Adam

[06YarisRS]

Originally Posted by atomic_hoji

Woo! Nice - glad it's worked out for you. Good call by WeeYari.

-- Adam

Yes! I have a new theory, unsupported by EWDs or anything wiring related at this point: The last time I introduced R134, it was cold in the garage. As I mentioned the suction tube became heavily ice encrusted. Maybe the pressure sensor/switch froze up. Tapping it and letting it sit allowed it to open and become operational. So, I'm going with WeeYari's pressure sensor suggestion as being the problem.

Merry Christmas, gentlemen! And, as always, thank you for the invaluable help.

[tmontague]

Originally Posted by 06YarisRS

How much does your A/C affect idle on the 2ZR? Mine seemed to labour slightly, until I removed a bit of the refrigerant. It still slows a few rpm when I engage A/C. I'm getting the impression that A/C systems are more power-robbing than I had initially thought.

The engine definitely has a noticeable load difference on it. For a small 4 banger it is quite a bit of draw on its overall power. I know dyno's online have shown anywhere from 3-6hp draw iirc. On a low powered engine this is a large percentage of the overall power output so it is more noticeable.

I'd purge a bit of your r134 out but I dont think you need to release much

[06YarisRS]

Originally Posted by tmontague

The engine definitely has a noticeable load difference on it. For a small 4 banger it is quite a bit of draw on its overall power. I know dyno's online have shown anywhere from 3-6hp draw iirc. On a low powered engine this is a large percentage of the overall power output so it is more noticeable.

I'd purge a bit of your r134 out but I dont think you need to release much

Yeah, it's significant. When I removed my manifold gauge high side port today, I noticed a bit of refrigerant bubbling around the bottom of fitting. I think the schrader valve is in a little fitting that may have loosened a bit after opening and closing the ports. I tightened it a bit and the bubbling stopped but the little sight glass seemed to not be full as before. My low side is reading 40, but the system didn't kick in today. I may have lost a little charge but I don't think any air was introduced into the system as it's still under pressure. I'll keep the system in its current state and in the spring, test it. At least I know all the components are functioning properly now - or at least I think they are.

[WeeYari]

Your pressure sensor may be finding its place onto your shopping list. Mine failed in 2014. I lived without a/c until last year when I finally diagnosed my non-functioning a/c.

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