How cold should the AC be?

Bluto

Bluto

New member
I've been using my AC on 'Lo' and recirc since summer started. That setting froze me last summer. Now it just gets by.

Does anyone know what the coldest vent temp should read?

It is probalby in a Factory Service Manual. It should be a standard diagnostic for AC trouble-shooting. I would like to know before going in for service. Thanks.
 
Register to hide this ad
Bluto said:
I've been using my AC on 'Lo' and recirc since summer started. That setting froze me last summer. Now it just gets by.

Does anyone know what the coldest vent temp should read?

It is probalby in a Factory Service Manual. It should be a standard diagnostic for AC trouble-shooting. I would like to know before going in for service. Thanks.
Click to expand...
Bluto,
re: coldest vent temp:
I can't find what you're looking for in my Toyota manual, it may be there but I don't see it. My Miata service manual states that when the temperature at the vent is 6 deg. C {43 deg. F} or less, "the AC compressor stops to prevent evaporator within cooling unit from freezing". It states this to be normal operation.
 
Thanks for checking.


Does the Miata run R-134?



I have a thermometer and a thermometer/hydro I'll take on my commute tomorrow and measure. It does not feel colder than 60.
 
Last edited:
Bluto said:
Thanks for checking.


Does the Miata run R-134?



I have a thermometer and a thermometer/hydro I'll take on my commute tomorrow and measure. It does not feel colder than 60.
Click to expand...

Yes, to be exact R134a.

That spec I gave you is for the "coldest" temp. On really hot days, it may never or rarely reach that point? It may be helpful to compare to other 4Runners under similar conditions. When my wife lets me drive "our" 4Runner :) I'll stick a thermometer in the vent (with recirculate on) and let you know.

Edit: Ok, I just checked the temp of the air from the dash vent with air on low temp, fan on low, recirc on, and engine at about 1200 rpm. It seemed to bottom out at 47-48 deg F and cycled back and forth between 51-47 deg F.
 
Last edited:
There's really no true answer to your question. The temp of the air depends on the outside ambient temperature. That's why your A/C can feel ice cold one day and just cold enough another day.
 
My A/C feels warmer than it did before as well....but it's also 106 today and yesterday... freaking ridiculous.
 
You should be able to make the duct temperature consistent, regardless of the weather outside. When the system is on max cooling and recirculate, the duct temp should get down into the 40's F. But true that if you're using fresh air, you'll always be at the mercy of the temp outside. That's why the climate control likes to turn on recirculate if you set it to "Lo".

But get 6 inches away from the duct during hot weather, and the air won't be anywhere near as cold as the duct temp.
 
toto said:
You should be able to make the duct temperature consistent, regardless of the weather outside. When the system is on max cooling and recirculate, the duct temp should get down into the 40's F. But true that if you're using fresh air, you'll always be at the mercy of the temp outside. That's why the climate control likes to turn on recirculate if you set it to "Lo".

But get 6 inches away from the duct during hot weather, and the air won't be anywhere near as cold as the duct temp.
Click to expand...

Nope... outside temp has everything to do with the inside outlet temp. The A/C system condensor is mounted outside of the vehicle and it's efficiency is primarily dependent upon outside air temp and flow.

A/C outlet temps will be warmer as the outside temp rises. Nothing we can do about that!
 
Fourty-four said:
Nope... outside temp has everything to do with the inside outlet temp. The A/C system condensor is mounted outside of the vehicle and it's efficiency is primarily dependent upon outside air temp and flow.

A/C outlet temps will be warmer as the outside temp rises. Nothing we can do about that!
Click to expand...
OK... I did some more research. A duct temp in the 40's is typical unless the ambient temperature is above 90 degrees. A more accurate statement is that the duct temp should be 35-40 degrees below the outside air temp.
 
toto said:
OK... I did some more research. A duct temp in the 40's is typical unless the ambient temperature is above 90 degrees. A more accurate statement is that the duct temp should be 35-40 degrees below the outside air temp.
Click to expand...

Sure, but it's all relative. If you turned on your A/C on a 50 degree day, you shouldn't expect the outlet temp to be 10 degrees!

I see too many people complain that their A/C system isn't functioning properly on a 100+ degree day. Here in NY, the temps have been about 99 degree for the last two days. My 4Runner's A/C works very well, but it definitely blows cooler air on days that aren't so damn hot. Either way, I'm fine with the windows up and the A/C on!
 
I was hoping Toyota would print some general guidelines. Charts would be even better.

If you know the intake temp and humidity, there should be a given range for the outlet temp. It is just thermo.

The low and high side pressures should also be within a range. Measuring them is beyond my hardware ability.



I've never had to use Lo and recirc constantly, which has been the case for three months. It is almost worthless in this heat.
 
Last edited:
biglatka said:

Edit: Ok, I just checked the temp of the air from the dash vent with air on low temp, fan on low, recirc on, and engine at about 1200 rpm. It seemed to bottom out at 47-48 deg F and cycled back and forth between 51-47 deg F.
Click to expand...


On the way to work, dash said 72 degrees outside. Driving 65 mph, vent temp was 52-56.

After I parked, still 52-56.

Probably about 90 in NY yesterday? You were running about 5 degrees colder, and it was 20 degrees warmer outside.
 
Bluto said:
On the way to work, dash said 72 degrees outside. Driving 65 mph, vent temp was 52-56.

After I parked, still 52-56.

Probably about 90 in NY yesterday? You were running about 5 degrees colder, and it was 20 degrees warmer outside.
Click to expand...

Yes, it was actually 91 on dash indicator when I tested it. I guess you'd better take it in as the tools needed to check it out further are probably more sophisticated than you have in your toolbox :) Good luck with it.
 
I don't know if you got your AC problem figured out or not, but.....if your vent temps are not where they should be, there is an easy way to "check" the condition of your AC sytem charge state. If the refrigerant is low, it will lead to higher vent temps. Between the grill and the bulkhead, on the passenger side of the truck, there is a small cylinder, (a little smaller than a soda can) with a couple of metal lines leading to it. On top of this is a small sight glass. With the AC system on and compressor running, the sight glass should be clear. If you are getting some cooling (if the system is empty the glass would be clear than too) and you are seeing a frothy mix of white bubbles, your system is probably low on charge and should be checked for leaks and recharged......
 
Along with the sight glass test, the compressor will cycle on and off frequestly if there is low charge.

The system will shut off if there is no r134 in it.

The humidity will have a lot to do with how cold it feels and how well it can cool.
 
Last edited:
You must log in or register to reply here.

Members online

Total: 365 (members: 6, guests: 359)

Forum statistics

Threads
278,307
Messages
3,554,053
Members
248,016
Latest member
Advally Service

Share this page

Trending content

Back
Top