2003 Honda - Air Conditioning not working - why and how to fix it

Question

The air conditioning has not worked on my 2003 Honda for about 1 year or so now. The weird thing is that right around the time it was going to break, the vents on the left side of the car was not putting out cooled air, but the right side was.

When it eventually stopped working all together, I had a guy come over and charge up the freon using a kit that I bought online. Right after he did it, when I turned on the AC, I can hear it got "bzzzzz, psssssst, bzzzz, psssst...". I think it was leaking out.

After that I took it to a shop and they supposed fixed it. They said that the temp got down pretty low inside the car. I tested it and they were right. I didn't need to use the AC much since it got fixed. However 6 months later (aka now) I really need the AC. When I turned it on, I occasionally would get the bzzzz, pssssst, bzzzz when I accelerate. The symptom of the left side vent not putting out cooled air is still there. The right side only puts out minorly cooled air.

My question is, what could be happening? I'm sure there's a leak in the system. Why is it that one side doesn't work but the other side might work sometimes?

What is the most cost efficient way to remedy the problem(s)?

Answer 1

I suspect that the "psst bzzz psst bzzz" sequence is due to excessive compressor cycling, because enough refrigerant (it's NOT Freon "R12", BTW ... for your vehicle it should be R134a) has leaked out, and opens the low-pressure safety switch, disengaging the compressor clutch.

Once the compressor is no longer "compressing", the high and low side system pressures equalize and close the low-pressure safety switch... allowing the compressor to turn back on, and this repeats over and over again causing the noises you hear.

I suspect the prior repair did not find the leak, or all the leaks, and the system was simply recharged and you were sent on your way. Since that time, enough refrigerant is "missing" from the leak to cause the poor cooling and noise you hear.

A thorough leak test is called for, using either vacuum decay, a refrigerant "sniffer", or injected UV dye. This can be expensive and tricky, requiring these specialized tools, and you will have to add to that the cost to actually repair the leak(s) once found, along with a proper measured recharge of refrigerant R134a.

The imbalance between one side of the vehicle and the other might be due to the shortest path for cooled air. Also check the vent flaps to make sure the discharge vents are actually open fully. There may be controls to change driver vs. passenger cooling, but I'm not certain which Honda model you have, and these features are usually reserved for the higher end vehicles.

The most "cost effective" solution is to simply add more refrigerant (but use the one that has UV dye added) to get you through the hot season, if the leak is small and slow. However, this is not a permanent solution, and it also has environmental implications, which frankly, makes this solution technically illegal in some jurisdictions -- certainly anywhere in the United States. While R134a is not ozone-depleting like R12 "Freon" was, it is still considered a greenhouse gas, and not permitted to be simply vented or leaked out. Cars are now transitioning to R1234yf, which supposedly has even less environmental impact, but may be flammable ... none of this matters to your problem at hand.

What does matter, is unfortunately the proper solution is to isolate and repair the leak, but this is quite likely beyond what you might consider "cost effective".

Answer 2

The periodic hissing is probably the compressor cycling on and off.

If your pressure sensor is functional, I wouldn't be surprised if there is too much refrigerant in the system.

You can confirm this using a manifold pressure gauge. Be sure to check both high side and low side to confirm that they are within spec.