Do I really need an evaporator replacement?

The dye doesn’t lie. If you can see it that’s where it’s leaking. Unfortunately buying a used car is the luck of the draw. It’s a lot of work to replace the evaporator, I would go with OEM brand for the evaporator and expansion valve as you have to take the entire dashboard out to replace them.

 

Yes 8 hours sounds reasonable because of the large job of removing the dash. When I changed the evaporator on my 4 runner it was a separate unit just behind the glove box. I wish they still made them like that

 

Where is that exactly?

My A/C went out this weekend to the extent it would only blow warm air on "max cool". The car is currently in the shop (Toyota dealer) and they have been giving me quite a song and dance. Probably because it was in a couple of months ago while still under their used car warranty for the exact same problem, and they "fixed it" by just recharging the system. This time first they said there was nothing wrong with it. I insisted there was so they escalated the problem. (Apparently the first mechanic you get is not guaranteed to be competent.) Then they said it might be a hose, or the evaporator core. So they are going to replace the hose. Which for some reason they didn't have in stock so it is taking an extra day. And then they are going to determine if the core is bad too. I don't understand why the extra step is needed, but in any case, I want to figure out how to confirm that the core is not leaking once I get it back without having to wait a couple more months for all the refrigerant to leak out!

 

It’s inside the ductwork that’s under the dashboard. You have to remove the entire dashboard to replace it so it’s a huge job. Figuring out if the core is leaking is quite easy. Turn the air conditioner on and put the proper halide detector (r134a) by a vent. If it detects r134a then your evaporator is leaking. That’s how I found the evaporator leak on my 4 runner. Couldn’t find the leak anywhere under the hood, but went off like crazy inside the truck.

 

Not the core, the tube. Where is the tube that would have dye in it if there was an evaporator core leak?

I'm hoping the dealer did exactly as you said with a halide detector, but given the run around so far, possibly not.

 

Everything is under the hood except for the evaporator and metering valve. The OP said you could see the dye under the passenger side mat, so look there for this tube. Has anyone ever put dye in your system? It doesn’t come from the factory like that, usually someone puts it in the system looking for a leak.

Don’t trust the dealer. Buy a halide detector and check yourself or go to an AC shop and have them check. Installing a new evaporator is a huge job. No dealer is going to want to pay that bill

 

The dealer claims to have put dye in last time, which is why it was a little odd that they couldn't find the leak. Are there any good cheap halide detectors? Hopefully this isn't something I'm going to need again for a long time, so if a cheap one won't do it would make more sense to go to a shop. Thanks.

 

When my 4 runner evaporator was leaking I never saw any dye, until I took the evaporator out that is. Then I saw it. From what I saw the Prius evaporator is connected to a metering valve that’s connected to the tubes that go thru the firewall. Like a sandwich. So the OPs leak was by the tubes but a leak could be anywhere, you might never see it.

I bought my halide detector on Amazon a long time ago, but I own a few cars so it was cheaper for me just to buy everything rather than take 5 cars to the AC shop for everything. Paid for the tools with my first compressor replacement by myself.

I would add if they could not see any dye anywhere under the hood then the only place the leak could be is where they can’t see. The evaporator fits that bill. A few spots on the condenser might too.

 

Adding my two cents here for whoever reads this thread later.

My 2006 Prius was leaking refrigerant. It started slowly, then accelerated. It now only holds the pressure for 6-8 weeks. I got a refrigerant leak detector from Harbor Freight for about $52 (plus tax); I used the 20% coupon. After returning from a 30 minute drive, and turning the car off, I tried to find the leak under the hood. I had no luck. Then I took detector inside, and as soon as I placed it near the vents it went off.

I haven't replaced the evaporator yet. There are other things that need fixing first, but I will do it this coming spring.

-Sax