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Discussion Starter #1 (Edited)
why a A/C evaporator temp. sensor needs to be in my Traverse????? Besides the Co. explanation IE: "To take the system offline when the ambient temp. is below 40."




I SAY BALDERDASH, POPPYCOCK, AND HOGWASH..........Just something else to fail, and it will, and be replaced.


Vehicles have run, with A/C's, for millennia without these stupid sensors.......Right?



BTW, it ain't easy to get to either.
 

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why a A/C evaporator temp. sensor needs to be in my Traverse????? Besides the Co. explanation IE: "To take the system offline when the ambient temp. is below 40."




I SAY BALDERDASH, POPPYCOCK, AND HOGWASH..........Just something else to fail, and it will, and be replaced.


Vehicles have run, with A/C's, for millennia without these stupid sensors.......Right?



BTW, it ain't easy to get to either.
Wrong. In the past, no one ran their AC when it was 40 deg. Nowadays, with "automatic temperature controls," the AC runs all the time to remove moisture. So now they need the ambient temperature sensor to turn it off below 40 deg F.

https://www.gmpartsdepartment.com/oem-parts/gm-sensor-25775833?c=Zz1odmFjJnM9YXV0b21hdGljLXRlbXBlcmF0dXJlLWNvbnRyb2xzJmw9NSZuPVNlYXJjaCBSZXN1bHRzJmE9Y2hldnJvbGV0Jm89dHJhdmVyc2UmeT0yMDE1JnQ9bHR6JmU9My02bC12Ni1nYXM=
 

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Discussion Starter #3
Wrong. In the past, no one ran their AC when it was 40 deg. Nowadays, with "automatic temperature controls," the AC runs all the time to remove moisture. So now they need the ambient temperature sensor to turn it off below 40 deg F.

https://www.gmpartsdepartment.com/oem-parts/gm-sensor-25775833?c=Zz1odmFjJnM9YXV0b21hdGljLXRlbXBlcmF0dXJlLWNvbnRyb2xzJmw9NSZuPVNlYXJjaCBSZXN1bHRzJmE9Y2hldnJvbGV0Jm89dHJhdmVyc2UmeT0yMDE1JnQ9bHR6JmU9My02bC12Ni1nYXM=

RIGHT!


Have a 97 Plymouth Grand Voyager with 2 evaporator cores, IE: 2 A/C'S in it, with 285k on it. Have put 1 1/2 cans 134A in it; thats all. System puts out 50 degree air when ambient is 101.


Why has it lasted so long? Main reason is on every COLD start the compressor comes on for approx. 15 to 20 seconds, thus lubeing the seals & O rings. And also, it don't matter what the temp. is when the A/C is in defrost mode the compressor is running..........WHY? to dry the stupid windshield out so it'll defrost.
 

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Discussion Starter #4 (Edited)
A/C 's 101


There is no difference between residential a/c and a car a/c. Say on a 3 ton residential a/c 1 ton is doing "latent" work IE: removing moisture(humidity). One can translate that to say that 1/3 of the tonnage on all residential a/c's is for moisture control. Their sized with that in mind.


Have 2000 sq. ft. home with a 4 ton heat pump. When the temp. is below 98 and the humidity is high the unit is removing several gallons /hr. out of the house. It runs like an open faucet.
 

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In my house when the humidity is a muggy 65% my ac can turn my number to 52% in less than half an hour. Who can sleep with a humidity higher than 60%. Not me.
 

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why a A/C evaporator temp. sensor needs to be in my Traverse????? Besides the Co. explanation IE: "To take the system offline when the ambient temp. is below 40."




I SAY BALDERDASH, POPPYCOCK, AND HOGWASH..........Just something else to fail, and it will, and be replaced.


Vehicles have run, with A/C's, for millennia without these stupid sensors.......Right?



BTW, it ain't easy to get to either.
It's right in the lower grille and like 15 bucks to replace. Small cost to potentially extend the life of a $500 compressor.

FWIW more than one professional HVAC tech has told me to avoid running my 4 ton residential unit below 50F. I like to test fire early in the spring so I don't end up with no AC on the first hot day.
 

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Discussion Starter #7
It's right in the lower grille and like 15 bucks to replace. Small cost to potentially extend the life of a $500 compressor.

FWIW more than one professional HVAC tech has told me to avoid running my 4 ton residential unit below 50F. I like to test fire early in the spring so I don't end up with no AC on the first hot day.

Wrong sensor, the a/c sensor is located in the evaporator core and it ain't easy to get to,hence it's expensive to replace....If, your not a DIY.
 

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Discussion Starter #8
It's right in the lower grille and like 15 bucks to replace. Small cost to potentially extend the life of a $500 compressor.

FWIW more than one professional HVAC tech has told me to avoid running my 4 ton residential unit below 50F. I like to test fire early in the spring so I don't end up with no AC on the first hot day.

Also, my unit is a heat pump which does the heating in winter. The pump will work fine down to 40 degree sometimes in the high 30's degrees. Then the strips take over. My unit has 4 - 5kw heat strips.which 2 come on at a time, depending on the outside temp.


A heat pump is nothing but an a/c unit with reversing valves.........a little more complicated than that. In heat mode it takes the outside air, extracts the heat out, yes there is "heat" in 40 degree air and above, and moves it inside the dwelling.


Why a heat pump? At 4 to 5 kw it's much more efficient to use than electric strips alone.Especially at $.10cents/kwh and above.
 

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Discussion Starter #9 (Edited)
In my house when the humidity is a muggy 65% my ac can turn my number to 52% in less than half an hour. Who can sleep with a humidity higher than 60%. Not me.



Capucine;


"Ideal" relative is 45%; above 55 its muggy, swamp conditions...........like Congress..( My Man is fixing that)


Below 35%, how dry I am.
 

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Wrong sensor, the a/c sensor is located in the evaporator core and it ain't easy to get to,hence it's expensive to replace....If, your not a DIY.
The OP first talked about the evaporator sensor, but then talked about it shutting off the AC for low ambient temperature. It's my understanding that the evaporator sensor will shut off the AC if the evaporator freezes up (this sensor and its use is very common in RV AC units, for example). BUT: I would assume it's the ambient air temperature sensor that prevents it from running with low ambient air temperature.

You can see in the attached diagram that both sensors are used.

So I guess we don't know which sensor he's actually talking about.
 

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Discussion Starter #11
The OP first talked about the evaporator sensor, but then talked about it shutting off the AC for low ambient temperature. It's my understanding that the evaporator sensor will shut off the AC if the evaporator freezes up (this sensor and its use is very common in RV AC units, for example). BUT: I would assume it's the ambient air temperature sensor that prevents it from running with low ambient air temperature.

You can see in the attached diagram that both sensors are used.

So I guess we don't know which sensor he's actually talking about.



https://www.autoblog.com/2016/01/07/symptoms-of-a-bad-or-failing-evaporator-temperature-sensor-swit/


This is the sensor in question.


Now, back to my original question........WHY IS THIS STUPID SENSOR NEEDED?????


High & Low pressure switches are common on these systems to take the compressor off line to prevent damage. Thats all thats needed. The car co's are everlastingly adding "stuff" thats expensive and gonna fail......I wonder why????.....A Rhetorical Question.



Compressors will ALWAYS shut down; for just about any reason, mainly due to a freon leak, also, various other reasons. Thats the nature of the beast on vehicle a/c's. And,also, thats why they're so expensive to have worked on. AND,AND,ALSO, thats why I do my own repairs.
 

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https://www.autoblog.com/2016/01/07/symptoms-of-a-bad-or-failing-evaporator-temperature-sensor-swit/


This is the sensor in question.


Now, back to my original question........WHY IS THIS STUPID SENSOR NEEDED?????


High & Low pressure switches are common on these systems to take the compressor off line to prevent damage. Thats all thats needed. The car co's are everlastingly adding "stuff" thats expensive and gonna fail......I wonder why????.....A Rhetorical Question.



Compressors will ALWAYS shut down; for just about any reason, mainly due to a freon leak, also, various other reasons. Thats the nature of the beast on vehicle a/c's. And,also, thats why they're so expensive to have worked on. AND,AND,ALSO, thats why I do my own repairs.
https://autoacrepair1.com/evaporator-temperature-sensor/
 

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Discussion Starter #13
Hey Green;


U seem hung up on these sensors. Do you make them & sell to the car co's?


If so, do you need a pardner?


I'm available.
 

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Discussion Starter #14
This subject has just about run itself in the ground.


Got another question;....MOTHER'S makes a product called CMX. Suppose to be a ceramic spray coating. Has anyone used it & does it work?


O'Reillys is really proud of it.....price wise.
 

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Discussion Starter #16 (Edited)
Well maybe I was just "venting". Thought I laid out a fairly reasonable, logical explanation of why these sensors are not needed. "Apparently" I have failed miserably.

Am not going to get in to a long, sad, sordid dissertation with you about this subject.

So lets just move on.
 

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My Texan Friend,

Chill! (see what I did there?) I don't really have any input on the AC system, I tend to understand electrical better than plumbing systems so I just replace what I need to replace and am generally unhappy to spend any money on anything ever, so I'll agree that these vehicles as a whole are way too complicated and cost way too **** much to fix.

Ok, on to something I know more about. I have heard that those ceramic sprays are more like refresh coatings for a vehicle that's had a real ceramic coating applied. Sure, it will work and make water bead up on your pain but it won't last long. If you want something quick and easy look at Opti-Seal or Blackfire Crystal Seal or a similar wax-on-walk-away type of product. I generally get 6 month of life out of them and I don't freshen during that 6 months. I personally use Opti-Seal, I apply in the evening then the next morning I top it with Collinite 845.
 

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Wrong sensor, the a/c sensor is located in the evaporator core and it ain't easy to get to,hence it's expensive to replace....If, your not a DIY.
The OP first talked about the evaporator sensor, but then talked about it shutting off the AC for low ambient temperature. It's my understanding that the evaporator sensor will shut off the AC if the evaporator freezes up (this sensor and its use is very common in RV AC units, for example). BUT: I would assume it's the ambient air temperature sensor that prevents it from running with low ambient air temperature.

You can see in the attached diagram that both sensors are used.

So I guess we don't know which sensor he's actually talking about.
Yeah you got me confused, I assumed you were talking about the ambient air sensor in the grille which will hold out the compressor at low air temps.
 

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Discussion Starter #19 (Edited)
My Texan Friend,

Chill! (see what I did there?) I don't really have any input on the AC system, I tend to understand electrical better than plumbing systems so I just replace what I need to replace and am generally unhappy to spend any money on anything ever, so I'll agree that these vehicles as a whole are way too complicated and cost way too **** much to fix.

Ok, on to something I know more about. I have heard that those ceramic sprays are more like refresh coatings for a vehicle that's had a real ceramic coating applied. Sure, it will work and make water bead up on your pain but it won't last long. If you want something quick and easy look at Opti-Seal or Blackfire Crystal Seal or a similar wax-on-walk-away type of product. I generally get 6 month of life out of them and I don't freshen during that 6 months. I personally use Opti-Seal, I apply in the evening then the next morning I top it with Collinite 845.

Well I've already bought the CMX so I'll give it a try and get back. Have not seen or heard of the products you list but will do a little research.


As for electrical vs plumbing? I've spent 50 years doing electricals from 12v dc thru 480 v wye or delta 3 phase ac.



Plumbing? if it don't leak before I get to it, it'll leak after I get to it..........but,I still do it.
 

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Discussion Starter #20 (Edited)
Yeah you got me confused, I assumed you were talking about the ambient air sensor in the grille which will hold out the compressor at low air temps.



I'm probably the one who is confused, thought the sensor in the evap.core was supposed to "control" the moisture.


Which begs the question; how can it do that in the first place????????! Since, ALL freon based a/c systems control humidity( moisture) by their very "nature".


And,Also, why would you want to take the comp. offline at low temps.? 134a has a boiling point of -16 F.


R 12 BOILED AT -21F......R22 boiled at -41F.........FWIW.
 
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