I recently picked-up a 98 Accord at a great price. It needed some minor work, some of which was the A/C not cooling at all.

Turns out, I needed to add a can of R124a (or whatever it's called) and now it cools great. The system holds pressure, no leaks I can find.

Which brings me to this question:

How does a closed system LOSE freon to such a degree that I need to add a can of the stuff?

I've had vehicles for 10+ years before and never have had to add freon. My home A/C system is 12 years old and I've never had to recharge that.

So if this Accord's system isn't leaky, why did I need to add a can of that stuff?

Yes, yes... I know, it's not really freon.. I just use the work colloquially.

 

leaks can be very small and take years for the system to become low on refrigerant...did you have dye added to the system? it's the most effective way to find leaks. and aside from the principles of "thermodynamics <<<<big SAT word" home a/c systems and car a/c systems are like apples and oranges.

 

Auto AC systems contain some components which are prone to leak w/ age:

1) compressor shaft seal - This is a rotating seal and seal wears w/ each rotation, so on older cars not unusual to see some leakage from shaft. This is usually indicated w/ an oily dirt covered ring around the compressor clutch rotation plane.

2) AC flexible hoses - These are rubber and have crimped end fittings. Crimps may fail w/ heat/age.

3) Oring seals at connections - This can age and leak also. I've found two old (90 & 94 EX's) Accords to both have leaks on the expansion valve orings where brass expansion valve mates to aluminum tubing fittings. Orings get distorted and leak due to dissimilar metals corrosion (white powder).

Home AC have sealed compressors (no rotating shaft seal) and fewer leak points, but some do leak. I recently replaced a 25 year old unit that required a charge every year.

good luck

 

Ok, I see what y'all are saying. My assessment based on studying the pressure gauges for about 2 hours was premature; a leak can be super-duper slow.

So I guess I do have a leaky system, but it's just such a gradual leak, that it appears fine.

 

You can only detect a leak by pressure gauge if it's massive. As refrigerant flashes from liquid to gas pressure is maintained constant. Pressure won't decline until all liquid evaporates.

Leaks are detected either by visible evidence (oil/dirt, dye, bubbles) or leak detector that can detect refrigerant.

good luck

 

*BONKS HEAD*

Of course! I don't know why I was looking at the gauges for a pressure leak... it could take hours or longer!

But now that you mention it, pressure in a can remains constant until the propellant is exhausted, and then it diminishes VERY quickly.

Thank you for this epiphany!