AC starting to fail, dx code 75

2009 Prius, 286k miles

Air conditioner has worked like a champ its whole life. Recently, started noticing less cool air mostly when idling. Today (VERY HOT for MN at 95 degrees outside and humid) it was horrid. When idling or even driving slowly with many red lights, there was no AC, even blowing HOT air sometimes. When at highway speeds, AC eventually seemed fine or just slightly warmer than usual. I CANNOT HANDLE HEAT. Need to fix somehow, either temporarily for upcoming road trips or long term.

The only DTC on my free version of Torque is for my catalytic converter (P0420).

Figured out how to check AC diagnostic codes by pressing AC/Auto + Recirc + power button twice.

Got codes 21 (expected, car in dark garage) and 75.

Where can I see what code 75 is? None of my search criteria here seem to turn up something similar.

IF IT MATTERS, in the past six months, I have DIY replaced:

1) inverter pump for second time in 2 years
2) coolant control valve (most recent fix, just before this AC symptom showed up)
3) blower motor for the fan.

Each of those repairs seemed to go as planned and address the issue at hand, but just in case there is a connection I am not aware of...

 

For me (free user) the service manual was not an option that came back after searching. Other interesting documents, but nothing I could see that had these kind of codes.

Maybe if you are a paying member?

 

A better Google search (not PriusChat search?) returned this thread indicating low coolant could be causing this... I will check the coolant since we did have to add some after the recent control valve replacement. Also I will ensure no coolant leaks after that process...

Ac code 75 | PriusChat

 

Thank you much.

 

Today I checked the coolant on "cold" engine, but hot outside.

Inverter coolant was just at the seam, so maybe a tad low. ICE coolant was smack in the middle between low and full.

I topped both off - to the full line on inverter coolant, and so I could just see fluid on the main overflow tank. (Topped off through the overflow tank.) Put engine in maintenance mode with no heat or AC on and cap off.

Could see "turbulence" in inverter tank. Left engine running in mtnc mode while I did some chores (through at least 2 fan cycles as a youtube video suggested)... when I returned, the fluid had expanded in the overflow tanks??? was at the brim on the inverter tank and had overflowed on the other tank and was sitting right at the top.

Hmmmm, I didn't think it was supposed to do that? Turned car off and left it sitting. I have a meeting shortly, so hoping during the meeting someone brilliant here can tell me it is fine and as expected?? I need to use the car almost right after the meeting ends, but will find a way to check back here before I head out to close caps and hood and race to an appointment.

THANKS IN ADVANCE.

 

AAAARGH.

Still had the problem today. When car is driving, I can have cool AC. When stopped at red light or drive-thru, air still blows but temp goes up until it's actually HOT blowing.

Any ideas?

PDF says Check Coolant - done (unless there is an issue as described in my last post)
Check DTC codes - none thrown with cheap ODBII and free Torque Lite
Next step says: REPLACE A/C INVERTER ASSY

I can't help but think that since this was my son's first attempt at coolant control valve replacement, that maybe it's related to that. This happened as soon as it got hot after the repair.

Big road trip coming up - WILL THIS HURT ANYTHING ELSE? Assuming I suffer without the AC (or will trying to run it hurt something?), can I expect the car to drive 300-400 miles without other issues? Will I fry or burn out the wires getting too hot?

Thank you.

 

Off to google how to check cooling fans.

Can I drive without overheating the engine? Not sure I have time for anotherre before the next road trip.

 

for the record, drove over 300 miles pretty much nonstop. no DTCs on Torque. Ice cold air the whole way.

I found where the fans are and will try to check them soon.