Weak Gen2 Air Conditioner mystery puzzle; dealer can't fix

The compressor is usually the problem with A/C. So if that is not the problem here, then you need to find a tech that will dig in. Potential sources of error are the A/C amplifier and the air mix servo/damper. These are deep in the bowels of the dash -- that interior part of the plumbing. If you post your town and state, perhaps one of us could suggest a shop.

 

1. What evidence do you have that the compressor is fine?

Feel the low pressure side of the AC compressor plumbing after the compressor has run for a while. It should be very cold and you may see water condensation on the piping. The high pressure side will be quite hot.

If the compressor is really running at full speed and you do not observe this, then I would question the assertion that the compressor is working properly.

2. Is it possible that insufficient, or excessive refrigerant is in the system? Has the pressure on the low and high sides of the system been checked?

3. Why not go back to the Toyota dealer who agreed that the system has a problem and ask them to consult Toyota tech support for assistance.

 

Dude, you are minutes away from *the* best Prius shop in the world:
Luscious Garage | Hybrid Specialists

If they can't fix it, it isn't broken.

 

Wow, Art's has one of the best hybrid reputations in North America. They have even written articles on hybrid A/C service by independents. Definitely give Luscious a try, they are well known for fixing tough problems.

 

I would like to see what Art's had to say. Unfortunately, you may be at the point where the dash needs to be disassembled to do further troubleshooting. The A/C amplifier is not cheap either ($475).

 

An hour and a half versus dinkin' around with it for another year. Your call :_>

 

I will troubleshoot it for 90 dollars over the phone.
if I cannot diagnose it , i'll give ur money back.

 

Here is a theory: Inverter Coolant Pump

Today I got the triangle of death on the dash, which is the Hybrid warning sign. I just left the dealer right now with it being replaced via recall. This is what happens when the inverter pump is dead: AC will blow warm even when you put it on 65F. I don't know the exact relationship with the inverter pump and AC. They must work together somehow because the AC is now FREAKING COLD. I live in Los Angeles and it was 102F on the drive back home. AC was set on 78 and on the second setting. I know the stealership didn't give a complimentary AC charge. Also, I noticed that the AC was blowing on the weak side a few weeks ago. Maybe the inverter pump was not running at optimum level and consequently lowering the AC temperature. My car is an 05 with 186k. I hope that gives you some clue.
Good luck.

 

The same thing happened to me last week. It would not trigger a code until it actually failed. Mine was 188K miles when it failed, though I have heard some failing much earlier.

 

i have a 2006 with 34K miles and am having similar issues. I live in Texas so it gets insanely hot here, but the a/c should work even in extreme heat.
my a/c blows cold then it would warm up a bit (to the point where i am not comfortable and start to sweat) then a few minutes later would cool a bit and then the process continues.

i took the car to my dealer and they found nothing wrong with it and said to return it when the issue was occurring.
i did exactly that and again they could not find anything wrong with it, even though they did a complete a/c diagnostic for free. their tests said it was blowing 40F and all systems were ok. on the way home from this testing the problem continued.

i took it a 3rd time and now they said a relay switch is faulty. He said the relay is tripping when the compressor gets too hot. He said they need to replace the compressor and another part (I forget the name) and to give them $2,300 to do so. Something doesn't sound right to me. If the relay tripped the unit wouldn't blow ANY cold air, correct? Do they want to replace the entire system because they cannot actually locate the issue?

I live near The Woodlands, TX (north of Houston) if that helps identify qualified mechanics.

Any suggestions? I greatly appreciate any assistance.

 

You might have a leak which has caused moisture to enter the system. That moisture will freeze and block the flow of refrigerant. The cold/warm cycle corresponds to the freezing/thawing of that moisture. Try calling around to A/C shops and see if any of them have the right equipment. High voltage compressors take special oil (ND-11 or equivalent), so if you find a shop that is aware of this, you are at the right place.

 

Thanks for the words of advice.
If you have a leak wouldn't the refrigerant be blown out under the pressure of the system and the unit would blow hot and quick burn out the compressor?

 

Moisture usually gets into the system when parts are replaced or when you drive around with no charge in the system for a long period of time or when the wrong person hooks up gauges to the system.

If moisture is your problem, you will have to recover the charge, replace the dryer, evacuate and recharge the system. The dryer is just a bag of desicant. Its job is to trap any last little bit of moisture that a good evacuation didn't get rid of. Liquid refrigerant flows through it all the time and it constantly scrubs out all moisture and everything works fine.

But .... when there's more moisture than the dryer can handle, the dryer can't hold all the moisture and the expansion valve starts to ice up. A dryer might work fine in 80 or 90 degree weather but when the temps get over a 100, the dryer's ability to hold moisture decreases and it will start to give up moisture. So you take your car to the shop and they check it in the shade with cross ventilation and all is fine. When you get back in the sun the trouble starts again.

 

yeah, that is what seems to be happening. worse in the hot sun. when 80-90 degrees it seems to work ok
I will print this out and give to dealer to be sure to check it.
thank you!!!!

 

I took it to another dealer and he said they have to replace the condenser and compressor. they said the compressor seized and must be replaced. nothing else to do.
great forum!

next i want to know how i can customize my LCD. I am tired of the "info" screen and want "audio" to be the default

 

This dealer that said the compressor seized is either using that term very loosely or he's full of soup! If your compressor has seized, you're getting no air conditioning. If you're getting some air conditioning, then the compressor has not seized.

There is something else you can do: find, yet, another shop!

 

Did anyone ever figure out what the solution was?
I've got the same air conditioner problem on a gen 2 2004 Prius.
I've asked Longo Toyota to look at it a couple of times but they always say everything is fine.

A few years ago I ran over a curb and damaged parts of the air conditioner which are positioned low in the front of the engine.
Longo replaced it but the temperature problem didn't occur immediately but a year or two later so I don't know if it is related.