AC Compressor Question--After Wreck

The pressure switch in the high pressure line will prevent the compressor from turning on if the pressure is out of spec.

Are you using the AC volts position on your digital multimeter? The compressor is powered by 3-phase high voltage AC.

 

1. I assume you are measuring voltage from one terminal to the next?
2. Use your meter to measure AC voltage coming out of a wall outlet at your home, to make sure the meter is working properly.
3. No accident damage to the orange wiring harness to the AC compressor?

 

You won't see much using a dvm. You really can't measure anything between the wires like that. There's no ground.

You need a 3 phase power monitor to analyze 3 phase voltage and drive and pwm. Its complicated. Its 200 volts from the Invert.
At worse you may hurt yourself and at best damage the car further.

Its obvious the compressor is or the control wiring to the compressor. is damaged. Most likely got fod'ed when the condenser was destroyed. We have seen that many times. The ac system on a Prius is pretty complicated . And the car should be throwing multiple codes also.

 

I would back up to square one and ask the A/C system for its diagnostic codes. On a Gen 2, I think you do that on the MFD, but I don't have a Gen 2 so I can't walk out and test it. It is not something you need a scantool plugged into the OBDII port for ... more like you touch the right buttons in the right sequence while turning the car on, and it shows you code numbers (Gen 3 they show up on the heater-controls LCD of course, Gen 1 they blink on the A/C light, Gen 2 I think they show up on the MFD but you'll have to search the forums here to find the exact procedure).

As to why your compressor isn't starting, my first three guesses are that Scotty, on the engineering deck inside the HVAC controller, is saying "Captain, I willna start the compressor under these conditions", and if you ask for the codes you'll find out what conditions he's talking about.

-Chap

 

No there are no diagnostic codes available on a G2 MFD. Lots of people have posted gibberish manufacturing data found on it though. You need to pull the codes using a OBDII device.

AC faults won't be Hybrid codes unless its affected the Inverter and the Inverter is throwing a ground fault. So an auto parts store should be able to pull the ac fault codes and there will be a bunch of them but to be thorough I would get a mini vci and pull ALL the codes.
See if any part of the Hybrid is unhappy. My guess is yes the Inverter is not happy to boot.

I see rebuilt compressors on ebay rather inexpensive. If it was me I would stop messing around and install a new compressor and then take it to a competent ac shop and get it vac'ed down and charged up and check for leaks. Bet its got debris in the lines and bet its got leaks.

I like to bet.

 

Yeah stop doing that. Your not accomplishing anything. If you had the factory manual you would see numerous cautions about that area.

Go to techinfo.toyota.com and you can rent a one day subscription of the factory service manual including all the troubleshooting tree's.
Get your printer ready for a workout. Print out all the diagnostics for ac issue.

The Prius ac if memory serves has a run control circuit circuit from the compressor to the Inverter that reports to the Inverter hey I'm ok...give me power. Then the INverter powers the compressor.

If the Inverter does not see this control line report it shuts the Inverter AC power down. This all happens in about 20 msec's.
You cannot fire up the 200 volt ac 3 phase power to the compressor without that report to the Inverter.
Another words you cannot disconnect the power lines to the compressor and think your going to see voltage there.

Don't work that way. There's communication there. The compressor is faulty or the wiring is damaged.

 

If you like to bet, would you like to bet on that?

The procedure found in this post is: hold down the 'auto' and 'recirc' buttons on the steering wheel, while stepping on the brake and powering on the car. Wait to hear a beep and see the MFD switch to the climate control screen; look for any 2-digit codes shown in the top right corner.

I don't have a Gen 2 to run out and try it on, but that is close enough to the procedure for my Gen 3 that I'd be inclined to believe it.

This is not some magic answer to reading all DTCs without a scantool, it is only for HVAC codes. The repair manual will have a table referencing the two-digit codes you can see here to the 5-character DTCs you would get with a scantool.

It is easy to make a code 21 (by placing something dark over the solar sensor on the dash), so that would be an easy way to check whether this procedure works as advertised.

-Chap

 

I just checked it out and yes, Chap, you win the bet.

 

Yep Chapman that's a good one works good. Sorry I thought you were referring to the hexi gibberish we have seen here so many times thats on the mfd.
Mine threw a 21.

 

You must use only special ND-11 oil in the ac system. Anything else will conduct and cause high load to Inverter.
Go to tech info and get the ac info. There's very specific troubleshooting tips and tree's. ND-11 is the most important. You cannot use regular oil.

 

Also while you're at techinfo, you can look up what the codes 21, 33, 41, and 72 are telling you.

(21 was mentioned earlier, just means the solar sensor is in the dark. It doesn't indicate a problem unless you get the code some time when sun is shining on the sensor.)

Looking up the codes is usually where I start. I figure if the computer is trying that hard to tell me what the trouble is, no reason I shouldn't listen.

-Chap

 

The hexi gibberish is useful for some things too, and the repair manual explains what it all means. The only thing that usually disappoints people is they discover it and think it is some complete readout for all codes in the car, when really it is only for audio, nav, and other things connected to the AVC-LAN. Usually, that isn't related to whatever problem someone is trying to solve. On the other hand, when you do have an audio, nav, AVC-LAN or gateway ECU problem, it could tell you just what you need to know. I used it plenty in my old Gen 1 when I was trying to get an iPod interface to work right....

-Chap

 

You are supposed to add refrigerant after you have drawn the vacuum and prior to running the compressor. The correct charge is 15.9 ounces +/- 1.1 ounce. Use only pure R-134a; do not use refrigerant that contains oil unless you use the correct ND-11 oil.

After you have done that, disconnect the 12V battery for a few minutes to clear the DTC logged by the AC amplifier. Then try to run the compressor and see what happens.

If you get the same blink codes as before then you may need to replace the AC amplifier.