I have a 2018 CRV LX 2.4L with 141k miles on it. The AC is blowing hot air and I hear a hissing sound coming from the vents and from the side of the engine facing the cab. Before this happened the air would go from hot to cold and now finally it's all hot air. The pulley's are turning under the car but I can also hear hissing from the back of the engine facing the cab area. What is the most likely issue?
What is the most likely issue?
There is no single most likely issue when dealing with air conditioning problems. It is necessary to perform diagnostics to determine the cause.
Have you checked your high and low system pressures? Refrigerant may have leaked out. That vehicle uses the new R1234YF refrigerant, which is very expensive and you would need a compatible gauge set to check (unique fittings are used). Is the AC compressor clutch engaging?
You can do some diagnostics with temperatures of various AC components:
That system is computer controlled so the problem could be in the electronics. There could be a problem with your temperature blend door, sensors, or the HVAC control module. A professional-grade bidirectional scan tool would be required for diagnosing the electronics.
If you are not familiar with working on air conditioning it would be best to take the car to a good independent shop for diagnosis and repair.
@chucktobias Update: A few hours ago I took it to a local repair shop. They recharged and did a dye test to check for leaks. They didn't see any obvious leaks and told me to cone back in a week to check again. Now I don't hear any hissing anywhere now and the AC is cool. Is this good or bad?
It may be good depending how thorough they were in checking for leaks. I prefer using an electronic detector to find leaks.
They think it was normal seepage through gaskets because of changes in pressure over time.
There should not be any seepage except for a tiny amount to keep the compressor shaft seal lubricated. I've had cars go way more than 8 years without losing enough refrigerant to make the AC stop working.
Did they check the service valves for leakage? That's a common leak point that is sometimes overlooked.
@chucktobias It's been hours since I left the shop. I can check on it later.
They think it was normal seepage through gaskets because of changes in pressure over time. After all the car is 8 years old
That's a lie. It's not normal.
They're just too lazy/inexperienced to look for leaks. There can be tiny pinhole leaks invisible to the naked eye, and they are often underneath clamps where moisture and dirt accumulate and you can't see them.
I think you'll be back to the shop with low refrigerant in relatively short time. (more $$$ for them)
@chucktobias Update: I just got back from the mechanic and they found no dye leaks in the system. They think it was normal seepage through gaskets because of changes in pressure over time. After all the car is 8 years old. All major components are working normally.