Interesting air conditioner issue

Long time lurker, first time poster. Background: 2004 Prius, 91K miles, bought new at local Toyota dealer, always serviced there, traded in at same dealer in 2014, I bought it there from the used car section. Carfax report shows no record of any crashes. California high desert with summer temperatures often exceeding 110 degrees F, which means I really need the AC.

Last summer, it started blowing warm air when stopped in a drive thru or at a long red light, but would cool off when moving. Checked radiator fans, and both spin and blow air toward engine. Never really had a chance to take it to the dealer due to work schedule. The AC always blows at least generally cold when first starting, but then not cold again at a stop.

Now I have a new job with a 3-mile commute. Now moving at speed isn't a reliable way to get it to cool. When I leave work at 5, it will be cold (not really ice cold but kind of cold) in the parking lot but warm up when I get onto the road.

Here's the interesting part: the air starts to get cold as I get to be a block or two away from my house -- probably 5 minutes or so into the drive. I guess I should try driving longer to see if it keeps staying cold and for how long. But now I wonder what could make it act like that. All the prior threads I've found here don't address that last part, which is why I started a new one.

Thanks.

 

Is it possible the fans spin but too weakly? Coolant level is up to the bottom of the cap, and looks like some kind of red but hard to tell against the black plastic. Condenser has the usual bugs but is otherwise clear. Cabin air filter had some bugs, leaves, etc. but isn't too dirty otherwise -- air should have no trouble passing through.

Ambient temperature of around 75 this evening. With a/c on "max cool," kitchen thermometer shows air temp of 68-70 at the dash vent. Turn the temp up one degree, to 65, and temp at the dash vent climbs to between 75 and 80. Does that mean I need that control module mounted to the floor under and behind the center of the dashboard? And does the relatively not cold, but cooler, temp when on max cool mean low R134a? Weak radiator fans? Failing compressor? The compressor is definitely heard when the car is at a standstill with the gas engine and stereo off, but the noise is a mix between a hum and a buzz. No high-pitched whine. No bubbles or foam in the sight glass when I shut off the a/c.

The records from the dealer on the Toyota owners' site show one "a/c concern," but at the same visit, there was a complaint that the radio would cut off while driving, and the dealer said the multifunction display needed replacement, and the air conditioner concern was related to the radio issue.

 

The trade-in happened almost a year later, though, and at the same dealer where I bought it. So it never went to auction. It was also bought new at that same dealership, and all the dealer service records are from that dealer.

Ridgecrest is a pretty isolated part of the state. I'm pretty sure an engineer on the base owned it and traded it in after retiring -- it only had 81K miles in 10 years before I bought it. Other than the dealer, service options are limited. No specialty a/c shops. There are a few garages, but I don't know if any have the special equipment for the Prius a/c. I hope Toyota of Ridgecrest has it -- they don't keep the HID headlight bulbs in stock, for example. But I would guess I would need to go to Lancaster or Victorville (roughly 90 minutes away) or Bakersfield (2 hours) to find more than I can get here.

Also, the Toyota of Ridgecrest service department is only open 7:30-5:30 M-F, and I work 7-5 M-Th, 7-4 one Friday and off the other Friday. So my options to take it to the shop are limited. So I'm really hoping to figure out as much as I can before going to great inconvenience to take it in, and would like to find out how much of this I can tackle myself in my off hours, instead of just "take it to the shop." I can do most stuff in my garage but don't have the level of equipment needed to take apart a closed air conditioning system. I also don't have the funds to fix it by trial and error. And if I'm looking at $2K for replacing a compressor on a car with a KBB trade-in value of $3,500, I would have some thinking to do.

So those are the reasons why I'm posting here instead of simply heading to the dealer.

 

An update for someone searching later:

The compressor needs replacement. It's heating up significantly, and the low pressure side is too high (50-55 as opposed to 30) and the high side is too low (115 instead of 150). It's also very loud. Quote for parts and labor is $1,302. The condenser, etc. seem to be OK, but can't really be diagnosed until the compressor is changed. So it could be as little as $1,302, but if they open the system up and find the compressor has sent metal bits around, then a lot more stuff would need to be replaced and my cost could double. No one would know the true cost until work begins, and of course once the compressor is off I would be pretty much committed to see it through.

So I have some decisions to make, but just wanted to update in case someone has the same problem later.

 

I would need to acquire a bunch of specialized tools to work on air conditioning, such as an electric vacuum pump (or an air-driven one with a much larger air compressor than I currently have) and so on.

The overheating compressor does explain why I have no cold air at a stop, I do have cold air at high speeds, and why the point where my air starts cooling off is between 25 and 35 mph. Also why I have cold air when I start the car the first time of the day (hasn't overheated yet).