2006 Prius-where is A/C 134a pressure sensor switch?

For about a month I was in the happy position of being able to illustrate my replies with pics out of techinfo, because I bought my first Gen 3 about a month ago and I went for the $75 one-month subscription for learning as much about it as possible, so in that month I could easily even look things up for other people with other model years.

But alas, my subscription is used up; I'm sure I'll re-up it someday, but mostly only for answering my own questions (for which the $15 two-day option is usually plenty). I do hope that some of the posts with examples will help people realize what an extremely useful resource it is, though.

Under the wiring diagram (EWD) tab, you can immediately see what the pressure switch connections are (and which wires are which!) ... while, under the repair manual (RM) tab, you will find the complete correct procedure for recharging your system, if that's what you need to do; if I remember right, hot-wiring the pressure switch was not part of the recommended approach. There will also be a lot of good information on diagnosing the exact issues you're having so you don't waste time on the wrong trail (or being confused by having more than one issue without realizing it).

Good luck!
-Chap

 

Huh, that's inconvenient.

I noticed their site had some pretty unpromising-looking language saying you'd need some ancient version of Internet Explorer or something, and I was worried how much trouble I'd have using Firefox/linux, but it works just fine. I think they've kept that disclaimer around from some old unlamented early version of their site. Currently, it seems pretty well designed, uses standard HTML/PNG/SVG/JavaScript and ought to work fine in a typical modern browser.

The part with the most elaborate JavaScript going on is the wiring diagram, but it's for a really good cause, the way you can select components and wires and follow them all around the diagram, just exactly as you always wished you could do with a paper wiring diagram and couldn't.

Very refreshingly, they have not tried to make this system hard to use, they've tried to make it help you do stuff. There's a print icon on every screen. The regular print menu from the browser works fine too. No need to fuss with a camera. If you look at posts where I've used techinfo images in the post, I've just been doing simple screenshots.

When you sign up, you do click an agreement not to abuse the privilege. Also refreshingly, most people on PriusChat seem to behave fairly, making reasonable copies for their own later reference, using selected relevant bits in replies to other people's questions, and so forth, usually not redistributing mass copies. I'm encouraged to see that on PriusChat, and figure as long as both we and Toyota stay refreshingly fair, the resource will stay refreshingly available and easy to use.

I can't speak to your specific model year (without dropping another $15 in!) but remembering from my old Gen 1, that definitely wasn't the recommended charge method. The civilized approach was to charge a bit with everything off, maybe up to 14 psi or so, enough to easily run a leak detector around the system and see what you find. If no leaks, then continue to charge up close to the right amount, or at least enough to make the pressure switch. Then you don't have to jump anything, and just swap your connections and finish the charge with the compressor running.

Just be sure to follow really closely your manifold valve changes and cylinder position between those different steps, lest you either slug the compressor or blow up your gas cylinder (potentially Darwin-award eligible).

-Chap

 

Hmm, I thought I replied to this yesterday, maybe I never clicked Post...

Anyway, there ought to be two side valves on your manifold gauge set ... that's how you can use it in the official, civilized procedure for charging when the pressure is too low to start the compressor yet.

But really you should read and follow the procedure very attentively (especially regarding when to close and open which valves, and change positions of the charging cylinder) because there are two different Bad Things that can happen otherwise....

-Chap

 

"Normal" is not 40 psi. That is your first problem. When the correct amount of refrigerant is added, the low pressure side should measure from 22 to 36 psi and the high pressure side should measure from 198 to 228 psi under the following conditions: air inlet temp is around 90 degrees F, fan speed high, temp set to MAX COLD, all doors open.

Since you have excess pressure on the low side, you definitely need a gauge to read pressure on the high side so that you can start to figure out what the problem is. You may have excessive refrigerant in the system, air may have leaked into the system, the condenser core may not be getting adequate cooling from the fans, the expansion valve may need to be replaced, or the compressor may have failed.

You are correct that the pressure switch is located on the high side.

 

The OP might not be able to measure those yet, as those are while-operating numbers, and OP reports the compressor won't run.

When the A/C is off, I would expect to read similar pressures on both sides, at least long enough after shutoff for the hissing noises to have stopped. I haven't checked what that equilibrium pressure is on my car, but something lower than the operating discharge pressure, and higher than the operating suction pressure, would not astonish me.

There's also a strong dependence on ambient temperature, strong enough that many references will present a temperature/pressure table rather than a single nominal number or range.

Anything I say here should be superseded by what the manual says, but if I recall correctly, a resting pressure of 40 ought to be adequate to satisfy the low-pressure switch, and well below tripping the high limit, so other possible reasons why the OP's compressor won't start might bear investigating. The codes from the A/C amplifier could be very helpful in pointing the way.

-Chap

 

What are the things that are cause by failing elections. Compressor in prius. I got a 320k Mile prius 09.

 

Try again?

 

Maybe he thinks the current political situation is causing a Prius failure.

 

Patrick!
Maybe he's kinda, under pressure somewhere?

 

Too many to count.