Troubleshooting the A/C System.....

First of all, please all apologies if this has been discussed....I just have searched for many days to get all the information I can but at the same time I'd like to ask some questions because I can never find all the information I need and I feel I could spend weeks looking across threads to find this.

I recently purchased a 2004 Prius knowing that the A/C system had recently died due to a leak (said by previous owner -- though they did not know where the leak was) but I got a great deal on the car and felt at some time in the future I would gather enough know how to fix it myself or at least that was the hope.

At this time, turning on the A/C does nothing. There are no compressor noises, only warm air blowing like normal.

I am in the process of finding enough information to find the leak safely and restore all the systems. I bought a vacuum pump / guage set / r-134a / without oil in it. Also a dye kit.

It looks like the system did have some yellow dye in it. I used the dye ultraviolet kit to find residue and I can't find a any location that looks like an obvious leak.....I'm also not sure how many months ago they recharged the system.

My first question is: I know that the A/C compressor is very delicate if not taken into account. I've heard they are easy to kill if you run the A/C system without enough coolant or ND11 oil. So before I troubleshoot anything, I don't want to make anything worse.

I'm guessing I should first put a vacuum on the system to confirm there is a leak obviously, right?

Assuming there is a leak: should I first put dyed 134a into the system to see if the system comes online at all, meaning the compressor runs (or doesn't)? (assuming the A/C switches are all turned on inside the cabin on MAX A/C.

I'm a little confused about whether or not the compressor loses it's ND11 oil after a leak occurs or if it auto shuts off due to low pressure. I'm under the impression that these compressors fail soon after a leak occurs due to ignorance of the owner about how the compressor cools itself.

Or if it is normally pretty cheap to pay a shop to find the A/C leak, just pay up and go about changing out parts/refilling myself?

Thank you so much for all of you out there that have helped me solve my brake problems earlier!!! I love this car....but damn, it's really hot here in Hawaii and El Nino is sweltering us, and I think my traction battery is begging me to get the A/C going again!

 

Hey Patrick, thanks for your detailed answer! I spent another good 3 hours on PriusChat reading countless A/C stories trying to absorb information as fast as ND-11 oil absorbs water moisture! Ok, that's a little joke for all the HVAC guys out there that have been helping out the DIY'ers! Well, at least I'm trying to be a good student because I know people ask the same A/C questions over and over again and some senior members are no doubt tired of answering them! Just so you all know, I'm really doing my research even while I beg for your wisdom now!

I did notice that my cabin air filter is filthy so I ordered a new one of those. I'll wait for that to arrive before troubleshooting the system.

The BIG question I'm having.....
One thing I'm trying to understand is whether or not ND-11 oil has left the system and should I be worried about not knowing the amount that is contained within. The oil itself is a wildcard to me, because at least with the refrigerant, you draw a correct vacuum and weigh the refrigerant to add. An exact science. Easy!

The amount of ND-11 oil seems to depend on the type of leak, or how quickly it occurred, or whether or not the owner of the Prius (at the time of the leak) shut down the system after noticing warm air, etc etc etc. All of this information I don't really know the answer to...and so I won't proceed further until I know more about this and what steps a professional would take at this point.

I would hate to add the r-134a only to kill off my compressor shortly after. And hearing from Lech auto air conditioning on this forum makes me not want to be one of those newbies that kills their compressor due to ignorance. <---- No, I'm not one of them! (yet)

So. Anyone with any thoughts to add? I've also got the downloaded factory manual so thanks for that tip. The manuals are very very detailed. Which is great....and it's also going to take some time for me to absorb that too.

Thanks everyone for all your tips, advice and help!




I don't know the exact nature of the leak that occured because I purchased this car knowing the A/C system was recently dead and to the best of my knowledge the previous owner said the air warmed up over the course of a few hours time and I don't know if th