AC Evaporator Valve.

Not sure what an ‘evaporate valve’ is. That is not part of any AC system I have ever worked on.

The expansion valve should be on the evaporator, buried under the dash. Small chance it is accessible deep below the glovebox without tearing the whole dash apart

If you have freon and oil coming out under the hood you have other issues that are not your expansion valve. Were you messing with AC components prior to this leak?

You will need to fully discharge the freon to replace the expansion valve, or maybe not if it all pissed out. Whatever you do, DO NOT INTENTIONALLY RELEASE THIS INTO THE ATMOSPHERE. That is an @sshole move.

At minimum you need to have a competent shop fully discharge and capture the freon for you. Based on your post you should also have them do the repair, it sounds like you don’t have a clue what you are doing and risk spraying freon everywhere which is bad for all of us.

I highly recommend you just have a shop look at it. Any time you open the system up the recharge, there are a lot more things that need done than the average guy with a basic toolkit can understand or implement, this is not work for beginners.

Frankly it shouldn’t even be legal to sell refrigerant or AC parts at big box stores. As an HVAC technician I need a license to purchase refrigerant commercially.

 

The thermostatic expansion valve is attached to the evaporator, right where the liquid line enters. So getting to it is every bit as much fun as getting to the evaporator, and then just a little bit more.

 

As I understand it is 7 to 8 shop hours for an evaporator replacement. Maybe one hour less just to do the TXV (Thermostatic eXpansion Valve). Expect a big bill, and consider replacing the evaporator while you are in there, as they are known to leak. The evaporator itself from Toyota is $400-600 depending where you buy.

 

I’m curious what made you think the expansion valve was bad in the first place very vary rarely do they go bad on a Prius.

The labor rate to replace the expansion valve is the exact same as replacing the evaporator both located seven hours under the dash and you have to take the evaporator off to get to the expansion valve attached to each other.

as mentioned above if you’re changing the expansion valve replace that evaporator it’s going to leak.

no finding that reason for the smoke hopefully it’s something just easy like a hose rupture. Also not very common on Prius.

Number one leak source for Prius‘s condenser number two is evaporator.

highest failure rate cause a lack of cooling I find customer not keeping up the refrigerant level due to slow leakage

the next highest failure rate cause lack of cooling or damage to compressor is the technician who improperly recharge the system causes more damage than anybody else or anything else. Undercharged just by 3 ounces or overcharged us by two or 3 ounces.

 

Replacing Expansion Valve I hope this is the appropriate place to post this. If not, please LMK.
Last summer I found & fixed a leak in the AC on my 2008 Prius project car, but didn’t use it much in the winter (not great in deep snow, sucks on slippery hills). This summer the A/C only works at highway speed, doesn’t work at low speed or in stop-&-go traffic. Manifold gauges indicate high low pressure, low high pressure, so the expansion valve is most likely stuck open. Garages around here are thieves that hear cash registers ring when you drive-in with an A/C problem. I don’t want to spend more on the car than I paid for it, sooo…it’s fix it myself – or just live w/o A/C. BTW: No OBDII codes.
Q1: Does my diagnosis sound right?
Q2: Is pulling the cooling unit to change the expansion valve super-complicated or require any custom tools? (Forum notes suggest 7 to 8 hrs). The only thing I’ve done on this side of the firewall is change the cabin air filter. I have the shop manual and all the tools including a vacuum pump.
Q3: The one thing I don’t have is whatever is required to recover the refrigerant (rather than vent it to the atmosphere). What are my options? Can I rent one? If so, what is it called?
Q4: If I'm going to empty, open-up, fix, vacuum, then recharge the entire A/C system – what else should I do at the same time? e.g.: Change the desiccant bag & evaporator core (even if it is not leaking) and… what else?
Thanks everyone! I couldn’t afford to drive this Gen 2 if it wasn’t for this forum.

 

If you are going as far as replacing the expansion valve your next most common failure other than a leaking condenser are leaking evaporator for the price to the ratio of labor that is required just make the hurt of the pocketbook right now and get a new evaporator.

replace the desiccant material the sock that’s located in the condenser as you mentioned it sounds like you did some reading and research very good

1: I am curious if you look into the site glass is it crystal clear and you can see all the way to the bottom right shiny machined Aluminum ?
2: or does it look like it has a gray color a slight film on the inside of the glass kinda dusty or foggy looking ?.

The symptoms you describe almost sound like a expansion valve staying stuck open except for the fact you have a variable speed compressor that is electric not attached to the RPMs of the speed of the engine that would possibly speed up the rotation of the compressor making a pump more refrigerant and if you only had a slightly stuck open expansion valve would make it get a little bit colder .

and if it was a fan not working at idle but working good because of the air moving through the front of the car your high side would actually go up when you’re parked with a condenser fan not working.

If it’s actually working really good at sometimes while you’re driving down the road can you pull off to the side of the road if there’s enough humidity in the air and actually see condensation water droplets building up on the suction line going back to the compressor ?. This tells me if it’s a mildly warm day say 75° out or a little more with a nice strong sun and you’re getting nice cold air out of your ducts of your dash and on top of that you also have enough refrigerant left over to make it down the suction line and chill it below the dewpoint to condensate water it should be doing the same thing at idle .

Where I’m trying to get with this one is possibly if something is changing under your dash control and the heater control valve any of the door flaps or air flaps under the dash between the difference of parking stopping and being at idle or driving down the road.

For me I have miniature remote Bluetooth pressure transducer‘s and temperature clamps that I could leave under the hood of a car while I take it on a test drive to monitor and data log the difference between driving down a road and coming to a stop.

Might wanna try just for the hell of it one other thing.
Some heater hose vice grips or just needle nose vice scripts with some rags or some rounded edges pieces a hose on the vice grips to keep the sharp edges off your heater core hoses.
Clamp off your heater core hose that supplies the hot coolant to the heater core.

at least that item will be out of the equation if it still has the same problem then we know it’s nothing to do with that.

with your thermometer in the dash take your temperature then clamp off the heater hose wait 10 or 15 minutes if the temperature goes down a few degrees and then you release the heater hose clamps and then the temperature goes back up a few degrees you know you’re looking at some control issue.

 

I agree with the symptoms matching a stuck expansion valve. Any blend door problem shouldn't affect evaporator temperature or low side pressures.

I would imagine that a restricted condenser would "starve" the evaporator and cause lower than normal low side pressures. The high side port is downstream of the condenser (and any restriction), so would also have lower the than normal pressure on the gauge.



It's mostly a huge amount of disassembly to get down to the HVAC housing. Lots of pics, small bags to organize screws. I would do the evaporator core while in there.

Depending on how much corrosion is present, I would give some serious consideration to replacing the condenser.

You could see what a local shop would charge to recover the existing refrigerant charge before you do any work.

Posted via the PriusChat mobile app.

 

Thanks for the feedback - very much appreciated!
1. Site glass is crystal clear and I can see very clear fluid going by.
2. I had not considered the fans... makes sense: cooling only when there is high-velocity air running through the condenser (except for the confusing high L and low H gauge readings when idling). I'll check that out.
3. I'll try the 'condensation-on-L-line' observation as well.
4. I'm not clear on the test to see if the heater line is flowing at low/no car speed. Can the A/C control unit erroneously signal the heating side to kick-in (when set to 'Max-Cold') whenever the car slows down or stops?
5. BTW: Residual system pressure (cold engine, before starting, 80F) is 80 psi; at highway speed, cold air from vents is 25F to 30F below ambient cabin pressure. Don't know if this helps.
6. If it is the expansion valve, I'll wait until fall or next spring to take the cooling system apart. And - given the work involved (I'm methodical, but slow ;-) - I'll definitely change the evaporator core, condenser & desiccant... as I plan on keeping the car. But first I have to find some way of safely removing the refrigerant.
Thanks-again for sharing your expertise!

 

Thanks for the analysis - very helpful!
1. I'll take everyone's advice and - along with the expansion valve - replace the evaporator, condenser & desiccant... given the amount of work I'll be investing in removing the cooling unit to get at the valve. But I think I'll wait until the fall or spring to do it, when I don't need the A/C. It will take me a few days, so I'll try to make a video documenting the process... if I can get a camera & light in there.
2. Based on your suggestion, I stopped at one A/C place and asked how much they would charge just to remove/recover the refrigerant. They said they would do it, but only IF they work on the A/C system... claiming it's probably the compressor because "that's what usually fails" (despite my report that it cools very well at highway speed). I'll try my luck at a few other places.
BTW: The .jpg file you attached has that 'broken link' icon, so I can't open the pic (or don't know how).
Thanks again for the help, this site is such a great resource for a newbie Prius owner like me!

 

4. Clamping off the heater hose is a general test to see if there is a physical fault with the air door that directs air through or around the heater core.

I wouldn't expect such a fault to affect system pressures or change with vehicle speed.

Posted via the PriusChat mobile app.

 

Update: A/C still cooling at highway speed (vent output 25F lower than cabin temperature); not cooling when stopped or in stop & go traffic. I pulled-over after highway driving on a hot humid day: a) no condensation on low pressure line to compressor; b) the rad fan that I could see was not turning (car still 'on'). Given that the A/C system can cool at highway speeds, I'm starting to wonder if the rad fans are playing a role in the problem... as suggested earlier in this conversation string. BTW: I can hear the air door in the heater/evaporator unit close or open when I turn the A/C on or off.
Q1: The shop manual always refers to the two fans in the singular sense i.e. "Cooling Fan Motor" or "Check that the cooling fan rotates" or "Disconnect the cooling fan connector" (even though there are two). Should both fans behave as one, or do they operate in stages or independently?
Q2: Pg. CO-18 of the shop manual shows 2 connectors: 'Fan Motor Connector' & 'Fan Connector'. Is each of these connector for a different fan?
Q3: If I disconnect the engine coolant temperature sensor when the car is cold, should both fans operate, or just one? And if just one, which one?
Q4: Any tip on how to check a fan relay to see if it's good or NG?
Q5: If I have to replace a fan, is the only way to pull one or both involve draining the cooling system, removing the bumper, disconnect a bunch of hoses, etc. (as directed in the manual)?
Thanks!

 

Get a scanner that can read the AC ecu. It will actually tell you what's wrong with it. My Camry Hybrid last winter showed a code for a bad ac compressor and was surprised with the internal damage when I worked on it a couple months ago. Your cooling fan should turn on when AC is on, it will not activate the AC if the fan is not working. You can supply direct 12v to the ac fan directly to test it. My Xtool A30D scanner has a bi-directional feature that can turn on/off the fan. TechStream can do that too.

 

The cooling fans are designed to work in two different modes. At low speed both fan motors are connected in series (12V - fan1 -fan2 -ground).

At high speed, both motors each receive 12V and ground (parallel). Each motor has its own connector.

The easiest way to test the system would be to use a scantool that has bidirectional controls and just command low or high speed cooling fan. Then test to see if power and ground are present at the motor connector.

I haven't done "just" a fan assembly on a prius, but in most cases you do have to do all the disassembly work. If the upper radiator cross member has to come out, then the bumper skin does as well.

Posted via the PriusChat mobile app.

 

I haven't looked at the cooling fan active test lately, but I seem to remember it just having on and off, and not giving a choice of the two speeds. I don't remember which speed 'on' was.