AC Can't Keep Up On Hot Days

This is not a common issue and I suggest you find another Toyota dealership to evaluate your AC system. Summer high temps here can be in the 110 degree F range and my Prius has no difficulty providing adequate passenger cabin cooling.

 

My Prius has the same issue. I have a 2006 Prius and I asked the dealership about if it is normal for a Prius to have to run full blast to try to cool off the air. In 100+ degrees, the A/C will cool off the air in around 15-20 minutes generally. The service adviser and the hybrid technician both told me that it is completely normal, and actually the Prius it the best at cooling. They told me it is so hot that the A/C has to work hard, so that's why it takes a long time to cool off. Also, they told me I need to get tinting, and that's part of the reason why it is so hot in my vehicle. I am not sure if I want to get tinting since I am not sure how many years I will be in Arizona, and I'm not sure how expensive it is.

Also, the A/C will be on high, and then it doesn't blow quite as hard, and I notice the A/C suddenly blows more air. Is this usual in the Prius? I have noticed it several times and just assumed it was normal. It does not do it every time I run the A/C yet sometimes after it has been on several minutes it will just randomly start blowing harder, even though it was on max the whole time. (This is generally when temps are 105-110 degrees.)

This is also strange too because I know someone who has a 2007 Prius and they run their A/C on medium, and it cools decently. This surprised me as mine had to run on full blast to even try to cool it down (until 20 minutes or so). Do you think having a darker color and/or lack of tinting may also have to do with why it is harder to cool off the vehicle?

 

Also, the hybrid tech told me that the A/C takes 20 minutes to cool off normally in hot weather. He did not look at my A/C system, although should I assume that the hybrid tech is correct? I know he is an expert at the Toyota Prius, Camry Hybrid, and Highlander Hybrid, since he is their hybrid tech.

 

Do you mean that the air in her car feels cool or that the cabin is actually significantly cooler? Just wondering, as my car, just like yours, takes 15-20 minutes to cool off in 100+ degree weather. My air feels "cool" although it takes a long time to cool off the cabin.

 

It is normal to take at least 15-20 mins to cool the car off in these temps. I feel that it takes longer because it's a hatch, and you're also cooling the trunk at the same time. You might feel more comfortable if you lower the fan speed manually, and then less of the cool air is blowing as far back into the car and may create a pocket of cool up toward the front where you are sitting. I even have my windows tinted, but there's not a whole lot you can do when it's 100 outside and the sun is beating on the car all day.

 

So then it might actually cool off easier given the fan is at a lower speed? How does this work? That's good to know that it is normal to take 15 to 20 minutes to cool off the car.

What speed setting do you recommend to run the A/C to cool off the front easier?

 

It could cool a smaller spot around you quicker if the fan is blowing at a slower speed. It would essentially create a pocket of air that's cooler in the front of the car than the back of the car.

You may want to experiment with the fan only blowing at half speed for a couple days to see if it works better for you.

Another trick I do, because I take lunch around 2pm everyday and have a 5 mile commute to get home, is I let the A/C blow on HIGH and angle my arm so the vent between the steering wheel and window sends the air right into my shirt sleeve. It's a great way to cool off your upper body and shirt, and makes you feel cooler. It also sort of requires you to angle yourself off the seat, so all that absorbed heat in the seat is not touching you at that moment.

 

Also, if you're typically the only one in the car, I believe you can close the far vent on the passenger side, and angle the others towards you in the drivers seat. You'll essentially direct all the air in your direction.

 

The Prius gets very hot b/c it has large front and back windows that let in a lot of heat from the sun. Window tinting helps a lot with this. For example, the tint I have cuts the heat from the sun by half.

If the car has been sitting out in the sun, the cabin air temperature is much higher than the ambient air temperature outside. If this is the case, open all the windows and drive a little bit so your cabin air quickly drops to the outdoor ambient air temperature before closing your windows. Then your A/C won't have to work as hard to get the cabin air temperature to a comfortable level.

A windshield sunshade also helps a lot with keeping the cabin cool. When the car is parked outside, the cabin itself (seats, floor, dash, etc.) gets heats up and the A/C has to work to cool this down as well. For optimal results, try to park so that the windshield with sunshade is facing the sun.

If you are keeping the air close to you cooler, I would keep an ear out for the traction battery fan turning on. If it turns on, the battery is getting a too hot, which is fine if the fan can cool it back down, but if it is on for an extended period of time, then the fan can't cool the battery and it would be better to cool the hatch area to help with the battery cooling than allow such heat stress on the battery.

 

I have noticed the traction battery fan turning on quite a few times recently. It has been coming on for periods of times. How do you cool the hatch area specifically? I am not sure if it is an "extended period of time," although I have noticed the traction battery fan for short periods, at least.

Also, I always use a sunshade and park under a tree (for shade) if at all possible.

 

I mispoke about cooling the hatch, as the battery intake vent is beside the rear passenger seat. What I meant was to have the air circulate instead of keeping a cool pocket of air in the front as suggested above. I personally don't like direct air blowing on me, so I have the vents pointed so they airflow follows the cabin ceiling, which provides a circular airflow through the cabin.

As for the battery fan, if it's turning back off, it should fine. If you notice it turns on, but doesn't turn back off, then the battery fan can't cool the battery down.

 

FWIW, I have a 2009 with tinted windows and live in south Florida. Today was 91F. I usually have the temp set at 77 F and experience the same "blowing like there is no tomorrow" forever. Somewhere about 20 minutes into my ride, I usually notice that I am comfortable but the fan is still working hard, so I up it to 78F to have quiet for the rest of my ride.

I am headed in for my 30K oil/rotate/inspect tomorrow and plan to have them check the A/C. I did the "LO with HI" check and do not see bubbles, but I can't tell that there is fluid in there either. I shined a laser in there thinking maybe it could show fluid flow; no. I have cooling, but not like three years ago - it used to freeze my driving hand, and now it is just cold.

 

I wonder if that would be coolant levels. I am not sure how the Prius A/C works exactly. I know it is operated using the electric components of the vehicle. Did the A/C used to blow ice cold for you? For me, it also blows "cool." I wonder if this depends on the level of coolant. I know the Prius has a lot of different parts than other cars oftentimes. (Different transmission fluid, etc.)

 

15 minutes to cool down after soaking in the Sun in 100+ degree weather is normal. Never cooling down in 95 degree weather is not normal.

In Auto the fan may run a little slow at first to limit the heat load on the compressor and its radiator, and so limit their internal temperatures and pressures.

*Do* use the A/C in hot weather because it provides cooling for the high-voltage battery.

This isn't rocket surgery :_> Anything you can do to reduce the starting temperature in the cabin will help: park in shade, or park facing the Sun and use a Sunshade in the windshield; open a door or window or use outside air (that is, the opposite of recirculate) for a minute to let the worst of the hot air out, and then close them again (return to recirculate).

 

That's a good point. Also, as you said, the A/C definitely drains the traction battery, since the A/C is electrically run. I think that's why people in hot climate zones see mpg significantly drop in the summer. In the winter, I was getting 46 mpg (19.56 KPL), and now, I am getting 39mpg (17.64 KPL) average (according to computer).

In cold climates, I hear it is the opposite. Is the heat also electrically run? I'm not too familiar with the heating system as it is generally not necessary where I am from. What mpg/KPL do you see in the wintertime?

 

If the vehicle is off, and it is in the sun, what does the traction battery do? I know the 12V battery can be gone due to extreme heat, but how does the traction battery last? Does the vent ever run if the car is off? Will the traction battery have a shorter life due to the extreme heat?

 

I think you are worrying about it too much. The battery fan doesn't run when the car is off, but the battery is also idle. If the battery got too hot while it was idle, then the battery fan would turn on as soon as you turned the car on.

 

After a hot soak the traction battery charge does sometimes appear low, but that may be the control system getting confused about the state of charge of the battery rather than actual discharge. In my experience in warm Sunny Dallas (true, not as warm as Phoenix!) it recovers within a few minutes, and after eight years it continues to perform well. I also advise not worrying about it.