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Discussion Starter · #1 ·
Hello all, it’s me again,

I’ve read A lot on sun load sensors here and how they can cause the HVAC system to stop engaging under certain circumstances. I am trying to confirm this is still my issue or if something else is going on

first, the symptoms:
1. My AC works, sometimes for weeks.
2. sometimes it doesn’t, and if I don’t do a certain thing, sometimes it lasts for a day or so until I do what I write below.
3. When my AC is acting up it will act up/stop working in these repeatable conditions:
- when I’m idle (in gear or neutral). This is usually temporary and will begin again when I’m moving again
- under heavy acceleration. This can be permanent. Heavy throttle will cause AC to stop blowing cold and will not cool again until I get on the interstate , get up to around 70MPH and the break down to 55mph (I have to drop 15-20mph within 6 seconds but not too fast or it won’t work). If my AC doesn’t work, this fixes my issue every time.
Sometime I can get the AC to work it i coast from interstate speeds to close to stop (like getting off on an off ramp) but that can sometime be a temporary fix that may not last more than a minute or two.

I took it to a mechanic and all they could come up with was that it was the sun load sensor or maybe the thermistor. I replaced the thermistor behind the glovebox hoping it would fix it because it would have been a cheap fix and an easy fix. It didn’t fix anything.

does this still sound like the sun load sensor since I can repeatedly make my AC blow cold no matter the situation?

Tha ks
 

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First of all have you had the freon level checked? It could be your electric fan motor running intermittently or your fan clutch is not engaging when temperatures increase. Also one last thing could be your compressor coil not energizing and maybe defective Have any of the these been checked?
 

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Discussion Starter · #3 ·
Thanks for the response, I can say the refrigerant has been check and the system has been found to have no leaks.

I had a mechanic shop check the AC compressor and they say it’s fine, but I didn’t specifically ask about a coil.

my electric fan runs all the time (once the AC is turned on the first time). It’s kind of annoying. I’m guessing there is a relay that needs to be replaced on that.
It could be that the clutch fan doesn’t come on when things get hot… what hot triggers are there for the clutch fan? If transmissions is one of them, it may not be functioning at temp (it does function in other ways though - I’m thinking specifically if cold startup )
 

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I know this may not be the answer, but on a different vehicle I had something similar. It turned out to be a loose connector to the a/c compressor. When I would accelerate or decelerate just right it would start or stop cooling. That accel/decel was just enough to wiggle the wiring harness and complete or break the connection.

This could be easy to check. See if you can safely reach the connector for the a/c compressor with the engine running and vehicle in park and front a/c on coldest setting. Give the wires or connector a little shake and a gentle pull and see if the compressor kicks off and on. You might also try the low and high side sensor wires for the same issue.

If that doesn't reveal any issues, at least it only cost you a few minutes and eliminated a possible problem. Be sure you keep your hands clear of belts and hot engine parts while doing this!

Good luck!

Thanks for the response, I can say the refrigerant has been check and the system has been found to have no leaks.

I had a mechanic shop check the AC compressor and they say it’s fine, but I didn’t specifically ask about a coil.

my electric fan runs all the time (once the AC is turned on the first time). It’s kind of annoying. I’m guessing there is a relay that needs to be replaced on that.
It could be that the clutch fan doesn’t come on when things get hot… what hot triggers are there for the clutch fan? If transmissions is one of them, it may not be functioning at temp (it does function in other ways though - I’m thinking specifically if cold startup )
I don't think the Armadas have a clutch fan. My 2008 has two electric fans. Just visually make sure both are unobstructed and running when the a/c is on.
 

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I don't think the Armadas have a clutch fan. My 2008 has two electric fans. Just visually make sure both are unobstructed and running when the a/c is on.
If your Armada has two electric fans then someone has removed the clutch fan and installed electric fans in place. As far as I know all armadas have a clutch fan and one electric fan
 
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