I have a pretty big leak in my evaporator. I can hear a hissing sound when it's pumped with freons.

So I'm going to replace it, along with the expansion valve and the receiver drier.

It's quite a drag to get to the evaporator since complete dash disassembly is required.

Is there anything else likely to fail that I should replace while I'm in there?


Sorry guys, I forgot to add the model. It's a 2007 Toyota Camry `ACV40 (JDM Model).

I figured out it's a leak because it keep losing pressure along with the hissing noise. Also I've never heard that kind of hissing noise before, it was like air escaping from a pressurized container through a small hole. The system has no colling whatsoever at the moment.

  • You do realize the system will make a hissing noise as refrigerant is running through the system. When the refrigerant goes from high side to low side (which makes things cold), it hisses through the expansion valve. I guess what I'm saying is, how did you determine where the leak is at other than the "hissing sound"? Oct 3, 2017 at 17:22
  • 1
    What is the year, make and model then there may be some suggestions
    – Solar Mike
    Oct 3, 2017 at 18:42
  • The vehicle make and model must be known to answer this question
    – Eric Urban
    Oct 3, 2017 at 21:26

2 Answers 2


9 times out of 10 freon is lost through old Schrader valves in either low or high pressure ports. I would replace them both while you are at it. On most models the heater core is also in a hard to get location in the dash. While you have the dash disassembled, inspect the heater core as well.

The evaporator and heater core are located there for thermal efficiency, being insulated behind the firewall and close to passenger compartment for close delivery of cooled or heated air.

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    High and low pressure ports are under the hood instead of behind the dashboard though, I'm wondering anything to replace after disassembling the dashboard.
    – Thihara
    Oct 4, 2017 at 15:55

One might evaluate the blower motor. If it is howling on cold mornings, or showing any signs of bearing wear, at about $50 to $70, one might consider replacing it while everything is apart.

It would be frustrating to have to replace it a year or two down the road, after you already took everything apart only a year or so earlier.

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