A/C Issues

[Will!]

Hello guys, my 2005 Silverado with auto ac is throwing me through a loop. When the truck gets wet like when I wash it the ac won't engage. The ac indicator on the climate control flashes three times and will not allow the compressor to turn on

 

I only seem to have this problem when it gets wet, all the other times it will work perfectly. I have had an issue with the low pressure switch and connector in the last and have replaced those, I don't think that's my issue but I figure I would mention it just in case.

 

Please help, I really don't want to have to take the truck to the dealer for diagnosis but it's driving me crazy.

[Will!]

I just wanted to update this topic, we are finally getting some rain here and the issue is back. I pulled the grill off and shot water directly into the ambient temp sensor and did not have a problem with it, I went as far as to electrical tape that connection to make sure as well

 

I'm at a loss, it's driving me crazy. If i take it to the dealer are they able to scan the truck and see if there are any ac faults?

[Will!]

I also wanted to add that when I am having this issue, if I disconnect the negative battery cable the problem goes away. But it always reoccurs when the truck gets washed. Is it possible that a sensor may have gone bad, is there any method of testing that or does it need to be taken to a dealer?

 

Thanks again!

[Jsdirt]

Could just be a bad connection on the compressor clutch. If it only happens wet, then it's definitely an electrical connection under the hood. Should be a relatively easy fix, since you know exactly where to look.

 

Get a spray bottle of water and do one section at a time until the problem happens again.

[Will!]

Do you think it's underhood and not some ambient temp sensor somewhere else?

[Doug_Scott]

I would take a look at the ambient temp sensor behind the grille. If outside temp drops below 0 (32 in the USA) the compressor will not engage, and will flash the light as you stated. Temp sensor is dirt cheap if that is it. $6 Canadian for the one I had to get. If you happen to have the temp displayed in your truck somewhere, what does it say outside temp is when this happens?

[Will!]

That's one thing I forgot to mention, the temp display on my mirror is still reading close to what the actual temp is. Is it possible that the sensor isn't connected all the way or that it is on it's way out? Where exactly is that sensor by the way?

[Doug_Scott]

My truck did not come with the temp indicator, I added it afterwards. The factory sensor on a 2010 is clipped to the upright bar thing behind grille, slightly off the right side(passenger side). Pretty easy to see, in my case it was the only thing down there. If you have two, one will be for the temp gauge, the other for the engine/trans/bcu. They may be interchangeable as well. Swap them and see if the problem moves to the outside temp gauge.

[Will!]

My truck did not come with the temp indicator, I added it afterwards. The factory sensor on a 2010 is clipped to the upright bar thing behind grille, slightly off the right side(passenger side). Pretty easy to see, in my case it was the only thing down there. If you have two, one will be for the temp gauge, the other for the engine/trans/bcu. They may be interchangeable as well. Swap them and see if the problem moves to the outside temp gauge.

Thanks. I will have to pull the grille off to see what's going on there. I have auto ac too so I'm sure I'll have at least two sensors. It's just a pain having to try and diagnose this since it only happens when I wash the truck. I'm wondering now though if I spray through the grille if that will cause the ac to stop working. That way I can kind of narrow it down I suppose.

[Doug_Scott]

On mine, there is a panel on top of the rad that covers the area behind the grille. I just pulled it off. Actually, it has to come off to remove grille(assuming you want to put that grille back on).

[Will!]

Yeah I was out looking at the truck earlier and I think I am going to pull the grille off as well. Thanks for the help so far. Worst case I have an appt at the dealer for a trans and coolant flush anyhow. I just wanted to avoid spending more if I was able to figure it out and replace it myself.