A/C colder on re-circulate?
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From: Memphis, TN
A/C colder on re-circulate?
My A/C is NOTICEABLY colder when I have it on re-circulate. I've been driving without the re-circulate turned on and have been considering taking it into the dealership to get my A/C looked at. It's just not really cold until I turn that on. Is this normal or should it still be cold without the re-circulate turned on?
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Normal.
Think about it. Let's just suppose your condenser cools the air passing across it by 30 degrees. cooling you interior air by that much will produce noticeably colder air over hotter outside air.
Think about it. Let's just suppose your condenser cools the air passing across it by 30 degrees. cooling you interior air by that much will produce noticeably colder air over hotter outside air.
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From: Memphis, TN
So why does the manual recommend leaving it set on outside air if it's a lot colder using re-circulate? Also, it is COOL, but definitely not COLD when using outside air. Is that normal? I thought it should be cold either way.
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From: Walker, La.
Originally Posted by WillJitsu
So why does the manual recommend leaving it set on outside air if it's a lot colder using re-circulate? Also, it is COOL, but definitely not COLD when using outside air. Is that normal? I thought it should be cold either way.
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From: Walker, La.
Originally Posted by engifineer
It changes it much more than that. Even on an 80 degree day your ac should be outputting approx 40 degree air. An ac only dropping 15 degrees is a broken one.
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Originally Posted by George
BTW, there is no single "magic temperature" for the AC to be "within spec" The repair manual test specifies the following:
(Repair Manual, page 55-4)
1. Cowl Inlet temperature (that's OAT) must be between 25C and 30C (That's 77F to 86F)
2. The technician must determine relative humidity by using a wet/dry bulb thermometer at the air inlet and consulting a psychrometric chart. Relative humidity must be between 30% and 70%
3. The vehicle must be stopped, in the shade, the door fully open, the AC switch on, engine at 2000RPM, inlet switch to outside air, outlet switch to face outlets only, temperature on max cold, blower on high, and high side pressure gauge at 1.5MPa.
4. The correct difference between the inlet and outlet temperatures is found by consulting another chart in the manual:
At 30% relative humidity, the difference between inlet and outlet temperature should be 19.5C to 25C. (35.1-45F)
At 40% relative humidity, the difference between inlet and outlet temperature should be 18C to 22,5C. (32.4-40.5F)-
At 50% relative humidity, the difference between inlet and outlet temperature should be 16C to 21.5C. (28.8-38.7F)
At 60% relative humidity, the difference between inlet and outlet temperature should be 14C to 19.5C. (25.2-35.1F)
At 70% relative humidity, the difference between inlet and outlet temperature should be 12C to 18C. (21.6-32.4F)
So, let's say that it's 80 degrees outside and the humidity is 40% The temperature difference is 32.4-40.5F, so the AC is OK if the outlet temperature is somewhere between 39.5F and 47.6F.
As you can see, the system cannot even be tested unless the outside temperature is between 77F and 86F. One also wonders if there are any Toyota technicians outside of Japan who can actually perform the psychrometric determination of relative humidity _and_ who have the equipment and motivation to do so.
If they're going to play the "46 degrees is the magic number" game, just pick the right day to take the car in. Even a car that is within spec according to the Toyota test procedure would be blowing air much warmer than 46F on a hot, humid day!
(Repair Manual, page 55-4)
1. Cowl Inlet temperature (that's OAT) must be between 25C and 30C (That's 77F to 86F)
2. The technician must determine relative humidity by using a wet/dry bulb thermometer at the air inlet and consulting a psychrometric chart. Relative humidity must be between 30% and 70%
3. The vehicle must be stopped, in the shade, the door fully open, the AC switch on, engine at 2000RPM, inlet switch to outside air, outlet switch to face outlets only, temperature on max cold, blower on high, and high side pressure gauge at 1.5MPa.
4. The correct difference between the inlet and outlet temperatures is found by consulting another chart in the manual:
At 30% relative humidity, the difference between inlet and outlet temperature should be 19.5C to 25C. (35.1-45F)
At 40% relative humidity, the difference between inlet and outlet temperature should be 18C to 22,5C. (32.4-40.5F)-
At 50% relative humidity, the difference between inlet and outlet temperature should be 16C to 21.5C. (28.8-38.7F)
At 60% relative humidity, the difference between inlet and outlet temperature should be 14C to 19.5C. (25.2-35.1F)
At 70% relative humidity, the difference between inlet and outlet temperature should be 12C to 18C. (21.6-32.4F)
So, let's say that it's 80 degrees outside and the humidity is 40% The temperature difference is 32.4-40.5F, so the AC is OK if the outlet temperature is somewhere between 39.5F and 47.6F.
As you can see, the system cannot even be tested unless the outside temperature is between 77F and 86F. One also wonders if there are any Toyota technicians outside of Japan who can actually perform the psychrometric determination of relative humidity _and_ who have the equipment and motivation to do so.
If they're going to play the "46 degrees is the magic number" game, just pick the right day to take the car in. Even a car that is within spec according to the Toyota test procedure would be blowing air much warmer than 46F on a hot, humid day!
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no i think our ac system suck horse ballz....if its above lke 80-85 the ac doesnt do justice...im taking it in for the TSB that was out for us..."SLOW COOL DOWN"...i too noticed that i had to do the recirculating fuction to get ti a lil cooler...but over all the ac isnt doing its job 100% -- i dont think so at least...
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Mine did fall under the group that was specified in the TSB, but mine will freeze you out of the car even on a 90 degree day, so I never bothered with it. I can always add a few ounces of R134 if needed (that is the the tsb). The only time mine has any issue is when it sits outside on a 100 degree day for a long time. It blows cold air in a fairly normal amount of time, it just doesnt seem to push enough volume to cool the car down quckly.
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From: Lombard, IL
Originally Posted by HOLLYWD69
Originally Posted by engifineer
It changes it much more than that. Even on an 80 degree day your ac should be outputting approx 40 degree air. An ac only dropping 15 degrees is a broken one.
pay attention to what he said. he didn't say that it would change the temp. 40 degrees, he said it should output air at around 40 degrees.