rpeAMP

So I thought I needed an R12 refrigerant recharge as my A/C has been performing lacklusterly here lately. Sometimes it was cold, other times kinda cold, and still others it was downright warm. I called the dealer, and they informed me that the initial charge would be $75 for one can of R12 and labor. At this point, they would diagnose where the leak was and fix it. I knew that the latter statement = $$. I figured what the hell, it's about to be summer in San Antonio, and I NEED A/C for all the city driving I do plus the fact I currently have no tint (not for long though). All that coupled with the south Texas sun is a LOT OF HEAT.

Anyway, as I was on the way to the dealer, I was doing some self-diagnosis as to the difference in the air temperature with the A/C on and off, since the temperature today was about 40 degrees F. Luckily, my stereo was off at the time, which is usually never the case, so I noticed an interesting pattern. With the A/C on, every 5 seconds like clockwork I heard a "click-click" coming from under the dash near my glove compartment. The second click followed the first so quickly it would seem they were simultaneous if not listening attentively. This cycle repeated itself every 5 seconds until I turned off the A/C using the button. I immediately thought some sort of relay. I don't have a manual handy, but I think I do remember some fuses etc. in this part of the cabin when I was running cables for my stereo. Before I tear out my dash to locate this mysterious clicking sound, does this sound like a feasibile diagnosis? Does the A/C have a relay or multiple relays that could be malfunctioning causing my compressor or whatever else not to get the power it needs to cool my truck off or do you think this could be a completely unrelated noise? If so, I'm thinking this is great news over having to diagnose a definitely expensive leak in the system.

Any ideas? I will provide any additional info needed whatsoever...

Thanks so much for your replies and concern in advance.

miket223

Sounds like you have a pressure sensor cycling the compressor clutch relentlessly. It could be other things as well but the pressure sensors are where I would start. Now, why the pressure sensors are cycling the compressor clutch? I would check your low side pressure first. Maybe your refrigerant level is too low, it could even be too high. Look for any dirty/oily spots thoughout the A/C system that might indicate a leak.

Now would also be the time to consider doing a retrofit to R-134a. You can buy retrofit kits at any auto parts store that will come with instructions on how to do it. Try to find some refrigerant with some stop leak additive in it. I had a leaking compressor and the stop leak worked like a champ. First, I highly recommend you take your truck to an A/C shop and have them evactuate the R-12, flush the system with a solvent, replace the drier and pull the system down to a deep vacuum. This will make it ready for you to perform the R-134a retrofit properly. Don't worry about replacing all of the o-rings, it has never been necessary on Toyotas.

rpeAMP

Hmmm...so you don't think with any reasonable certainty that it has anything to do with a relay or anything electrical. The sound is EXACTLY like a relay sound.

However, I will take these suggestions into consideration and thanks so much for your time!

miket223

Yes, what you are hearing is a relay. But, the relay is most likely doing it because the pressure switch is making it do it.

Michael

rpeAMP

Ok, so I finally gave in and took her in to the dealer. I talked to this really, really nice tech on the night shift and got there at about 10:20 PM. We found out that there was not a particle of refrigerant in the system whatsoever. We drained the system the "illegal" way, however it didn't matter much as there was nothing but air to drain.

After he filled it up with new freon, she blows colder than ever. I actually retrofitted to the new R134a. The "retrofit" is exactly that--two adapters for high and low pressure that you screw right on to the existing valves.

On a side note, I was noticing a hissing here lately which I thought was a leak coming from the compressor whenever the A/C was turned on. Turns out, according to the tech, that the noise is not a vaccuum leak like I had thought, but an actual sound coming from my compressor. He said that the compressor itself would eventually go bad and I would know that it had gone bad instantly because the belt would break loose. So we'll see when she decides to go...