A/C cold only on passenger side; barely cool on driver's side

Check the little wheel below each vent to make sure the vent is fully open. The wheel adjusts the volume of air coming out of the vent.

 

Is the volume of air different on each side or just the temp? If it were me I'd likely run the ac on high and set it to blow from the vents on the dash only. I'd then close the middle set so it was blowing on only the outermost 2 vents. From there you can compare the volume and temp in both regular and recirculate mode. You can use any household thermometer that measures temps between the 60s and 90s - I have used a digital cooking thermometer before.

This will likely let you figure out what is going on. The ac for both sides comes from the same source so it has to be an issue with the vent system or the doors that control air flow.

 

Ok. When the car is on recirculate the temp should be colder (as you are drawing in only pre-cooled inside air) and a bit more forceful. The next thing that I'd look for is air coming out of a vent that is not turned on. So with just the outside vents on the dash going I'd check the defroster and also the floor (both under the dash as well as under the front seats, blowing back into the footwell of the rear seats). This way we can make sure that the air is going where it should. There are doors in the system to control air flow and hopefully we can figure out if they are working as they should.

 

Sounds like the system is low on refrigerant due to a small leak. On some vehicle when the system is slightly low, the evaporator will only be cold on part of it's surface, causing the symptom you note. Perhaps someone with more Prius-specific experience will chime in on this one.

 

I suggest you look at the last lines in this post:
MFD issues on '04/'05 Prius | Page 20 | PriusChat

He mentions the same symptoms, and found the problem.

 

Well can I come along and throw a spanner in the works?

I have a gen3 (2010 model) and my a/c has been playing up and only works on the passenger side too. But I have a RHD Prius and thus my passenger side is your driver side.

My a/c appears to have a small leak as when I got the car regassed it blew ice cold on both sides but as it lost gas it got warmer on my side and stayed cold on the passengers.

The cure in your link above doesn't apply to the gen3 so I think it might just be that as the a/c loses gas, one side remains colder.

 

I agree with the above reply's about low on refrigerant. when the refrigerant gets low part or the evaporator is colder on one side and as the refrigerant travels to the other end it flashes off and there is not enough in the tubes further down stream to remove heat. On some cars because the way they vent the cold air into different duct picking up the air on the other side of the EVAP it will be uneven. on top of that the driver side is farther away from the cold source and there is much more warm plastic duct run to get to the driver side in the US LHD cars this will increase the temp out of the furthest duct. There is one Chrysler van this is so drastic on and the way it they pick up the cold air and distribute it, it can be 15F to 20F difference but in reverse. Warm on the passenger and cold on the driver when the refrigerant was low.

 

I have the same issue. I first noticed it last spring when I started using the Air Conditioner. It soon cleared up and just this month I noticed it again. Dealer says it is a known issue, possibly software related. They have been told not to attempt repairs until a solution is found, but simply rotating both temp controls simultaneously from cold to hot and back several times will reset the controls. This is a temporary work around.

 

any updates on this. My car is doing this now. Of course when its the hottest time of the year :/

 

The refrigerant level is probably low.

In post #5 the OP's reported temps are far too high. With a properly functioning AC system the air coming out of the vents should be in the high 30s F when the temp is set to MAX COLD.

 

I got that checked. It was completely full. The right side has been much cooler than the left. The right side still doesn't seem to me extremely cold. It has a real hard time when the temps are over 92f

 

Sounds like it is time to visit your local Toyota dealer service dept for help. Maybe the AC compressor is beginning to fail or maybe there is moisture in the system which is freezing up the expansion valve. After high and low pressure gauges are hooked up to the system and the compressor is running, hopefully the root cause will become evident.

 

Thanks! I tried doing the switch to heat then max ac a few times. Now the temp is even for now. Hmm? Hope it lasts.

Next 90f+ day we'll see if it cools off better.

 

cleaned the condenser, that one side seems to work good. Good not amazing, but I don't need amazing. The passenger side is nice and cold. At one point I closed both driver side vents so I could have only cold air from the other two vents. They will both blow cold for a little while after I do the hot-cold-hot-cold-hot-cold. This just seems so odd to me

 

There are two flips (for the right&left side) that controls heat/cool operation "inside the air conditioner" connected to a small motor that change the air-flow between the hot/cold condensers.
I believe that the one for the left side (driver side in your case) is stuck in the heat position (broken and separated from the other), this will bring air from the heating condenser (which is not hot when selecting low temp.).

The solution is expensive and hard, you need to REMOVE the dashboard and take the AC system out and then try to fix the flips.

 

Tareq, can you please elaborate a little. I've got '08 RHD and I noticed a drop in the cooling in summers, later on I noticed the difference of temperature in the 2 sides as well. Now that we're entering winters here, its behaving even worse. Even though the climate control is set to a constant temperature, once minute its blowing cold air in the face, and with the change of half a degree in the setting, it becomes very hot. Also while keeping it in Auto mode, I've noticed that at times the front windscreen becomes foggy (as if the compressor is not on) and I have to turn manually drop the temperature from my steering wheel to clean the screen.

Your explanation of the flips seems seems to be the issue with the different temp on both sides, but I think there seems to be some other issue as well, with the cabin temperature/humidity sensor. Can you please also guide as to where these sensors are located.

Thanks

 

There are no humidity sensors, in winter the AC compressor works to cool down the air "this will remove humidity" before heated.
in the case of broken flips in winter: one side will blow warm air "less than usual" and the other side will blow cold air.
You need to remove the dashboard then remove the AC system and fix the flips.