What should Vent Tempertaure be in Summer?

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pmcs
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What should Vent Tempertaure be in Summer?

Postby pmcs » Tue Aug 22, 2017 6:40 pm

Hi,
I have a 2012 Ram 1500 Laramie Longhorn. I recently replaced the Condenser and Evaporator and did not get the great cooling I expected. The vent temperature is around 60 degrees. My thought is that my expansion valve isn't opening up enough to lower the temperature in the vents. Yesterday, I took a long trip and after 1/2 hour of highway driving, the vent temperature got down to 40 degrees. Now I am wondering if my compressor isn't working correctly at low speed. I just went outside and took a reading at 82 degrees outside. At idle, were looking at 30/170. At 1500 RPM, i get 20/175. My trucks interior is about 140 degrees in the afternoon, so it would take a long time to cool down. However, shouldn't my vent temperature be a lot colder than 60 degrees initially ? My wife’s 2007 Avalanche has ice cold air right from the get go. This makes me wonder what is going on. I practically have a brand new AC system (except for the Compressor and Expansion valve). Thank You in advance for your advice !
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Cusser
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Re: What should Vent Tempertaure be in Summer?

Postby Cusser » Tue Aug 22, 2017 8:00 pm

I'm in Arizona, Phoenix and Prescott, so it's hot here - 108F in the shade today in Phoenix (as if there's really any shade !!!).

That said, the local radio show ASE mechanic says that vent temperatures need to be 55F or less. That said: my vehicles do better than that, measured with digital thermometer. Of course, there's more to cooling than low vent temperatures, like blower speeds, BTU exchange, etc.

Mrs. Cusser's 2005 Yukon has very good AC.
My 2004 Frontier 4-cylinder (98K miles on original parts) puts out 45F and has great-feeling AC, I have to turn off the AC periodically because it's too cold.
My 1998 Frontier 4-cylinder (222K miles on original parts) puts out 45F and has great-feeling AC, I have to turn off the AC periodically because it's too cold.
My 1988 Mazda B2200 truck (which is still R-12) puts out 45F but its AC is just "OK", not up to the quality of the two Frontiers. It's had a few compressors and a replacement evaporator.

I test drove a 2013 Subaru for my daughter in Phoenix and its AC temperature measured 45F and felt fine; two other Subarus in a town at 4000 ft. elevation only measured 48F and didn't feel so good, at 9am too.


Now, to your truck: Your vehicle should do way better for cooling.

pmcs wrote: just went outside and took a reading at 82 degrees outside. At 1500 RPM, I get 20/175. However, shouldn't my vent temperature be a lot colder than 60 degrees initially ?


Your pressures seem to indicate that your system is low on refrigerant. You may want to confirm by having the refrigerant pulled out and weighed, and compared to specifications. If low, then the leak needs to be found and corrected.

pmcs wrote: The vent temperature is around 60 degrees. Yesterday, I took a long trip and after 1/2 hour of highway driving, the vent temperature got down to 40 degrees.


That makes me wonder whether your fan clutch or electric cooling fans are not working properly, or maybe some of your radiator/engine shrouding is incorrect. When traveling faster, air is rammed over the condenser anyway.

Did you have leaks in your condenser and evaporator????
pmcs
Posts: 2
Joined: Tue Aug 22, 2017 1:44 pm

Re: What should Vent Tempertaure be in Summer?

Postby pmcs » Wed Aug 23, 2017 4:20 am

I had a small leak in my condenser. I replaced it, along with my radiator at the same time.
After than, I wasn't satisfied with the cooling, so I replaced the Evaporator. The Evaporator
was mud caked because there is no air filter in gen 4's. It was a Texas ranch truck before I
bought it and the only way I got air flow out of it was to take a garden hose, remove the
blower, and flush as much junk from it as a I could. It helped quite a bit, but was never right.
and I knew that I would eventually pull the dash and replace it.

When I pulled the dash and changed the evaporator, it had some AC oil on its surface, so it
must had had a leak as well.

As for weigh of the Freon. I use 12 oz cans. is that 12 oz by weight or volume? Should
I use a scale instead ?

Thanks,

Eric
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Cusser
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Re: What should Vent Tempertaure be in Summer?

Postby Cusser » Wed Aug 23, 2017 7:30 am

pmcs wrote:As for weigh of the Freon. I use 12 oz cans. is that 12 oz by weight or volume? Should
I use a scale instead ? Eric


OK, sounds like leaks in both condenser and evaporator.

I use cans as well, as I'm not "a professional" and do pretty much just my own vehicles.

R134a can be added by cans, note that the gauge lines need to be purged of air as usual, and realize that full 12 oz. will not get into the system. Oz. by weight or fluid oz. are pretty similar.

If you have a "new" leak now, chances are high that it would be at one of the connections you just did at the condenser or evaporator.

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