Air Con not coming on

have you tried both auto and manual?

is the fan working?

 

if you can, check the wiring at the compressor. hopefully no vermin or corrosion

 

some part has likely failed: either the compressor itself, or the start capacitor, or the relay that turns it on. if you have a multimeter you should be able to chase down which component is busted-- test ohms on the relay coil and compressor windings, and test the capacitance (in microfarads) of the capacitor.

if you don't want to mess with it yourself, take it someplace to be diagnosed.

if it's the relay or capacitor, it's a super cheap fix. it it's the compressor, prepare to pay.

 

here's the compressor, but i can't find a pic of the engine bay:
60-03675_NC

 

Low pressure cutout switch. Yes, that's quite normal in virtually all automotive A/C systems.

That's a heck of a lot less normal. Historically auto HVAC systems just don't do that. However, the Prius does have a sophisticated air conditioner with its own diagnostic system.

It doesn't really have a warning indicator; you have to ask it what is wrong. I can't remember the secret handshake but once you hold the right sequence of buttons the display will change and might give you useful info.

 

Prius HVAC doesn't have the traditional relay that you might be looking for. Regular cars typically had a relay to control the compressor clutch, and that relay was a common failure point. Prius has no AC clutch and therefore no relay.

There could be a different relay involved, but it won't be anything like the common 12v style in the fusebox of any other car.

Prius HVAC is different from other cars; if you take it into a general AC shop for re-gas make sure they realize it's a Prius; different tools and procedures required.

The HVAC controller is separate from the main ECU and does not participate in OBDII communication. Any errors detected by the HVAC system stay within it. You can push a pattern of buttons in the cabin and the display will give you a readout; not sure if techstream can see the same stuff.

 

More like this

 

I agree it's convenient to ask the A/C itself for its own codes. In Gen 2 and 3, you do that by turning the car on while holding the AUTO and FRESH/RECIRC buttons. I haven't looked up the specific procedure in Gen 4, but I would not be surprised if it's the same. (In Gen 1 it was different, you'd press the A/C button 3 times then turn the fan knob from OFF to AUTO).

At the same time, I don't think it's the case that you can't get the codes on an OBD-II scan tool. In the generations I'm familiar with, the scan tool will show a trouble code B14xy where xy is the two-digit code you would get from the HVAC control itself.

So, for me, the main attraction of the built-in HVAC code display is just that you can do it when your scan tool isn't handy.

 

If you go to the dealer, they will probably think of that themselves, but there's no harm in asking.

They'll probably go systematically, look at the pressure reading in Techstream to see if the 23 was posted because of low pressure or high pressure. If, as you'd guess, it's low, they'll probably want to rule out a leak, one way or another.

 

i would think it would be well worth it, as 6 years is way too short a time to lose that much refrigerant

 

if the pressure switch is tripping without the compressor turning on, it indicates that the system is flat (all the refrigerant has leaked out). you'll need to take it someplace to have them find and repair the leak, then refill it with new refrigerant.

it's possible that the pressure sensor itself failed, that would be the best case scenario. but more likely it's working as intended, preventing the compressor from running on an empty system and doing even more damage.

 

They'll take their own pressure readings, and if they confirm the system is empty they will likely fill it with a gas cheaper than refrigerant just to see if there's an active leak to be patched.

I didn't realize the newer versions of the car could forward error codes into the OBDII system. Figured it was still islands like in the past. That's nifty progress!