Automotive Air Conditioning Information Forum (Archives)

tcrosby2011 on Sun February 09, 2014 6:30 PM

Year: 1999
Make: Chevrolet
Model: Silverado
Engine Size: 5.3
Country of Origin: United States

Hey guys, I am new to this forum and I need some help. I have a 99 Silverado and when I turn the Ac on it will blow cold for about 5 minutes and then it will turn to more room temperature. I have not been needing it but its starting to get warm in south Ga and so i really need my ac. I know that it has enough Freon because I have checked it myself and the place that serviced my truck said it was fine. If somebody knows what my problem is I would be greatly appreciative.

Cussboy on Sun February 09, 2014 7:25 PM

Quote
Originally posted by: tcrosby2011
I have a 99 Silverado and when I turn the Ac on it will blow cold for about 5 minutes


That seems to rule out a refrigerant level issue.


Quote
Originally posted by: tcrosby2011
I know that it has enough Freon because I have checked it myself .


How you do this? Only real way is remove the refrigerant and let the machine weigh it.


Quote
Originally posted by: tcrosby2011
it will blow cold for about 5 minutes and then it will turn to more room temperature.

I would check the fans (electric fans or fan clutch) sounds like the condenser might be getting warm because of lack of air flow.




Edited: Tue February 25, 2014 at 1:07 PM by Cussboy

TRB on Sun February 09, 2014 7:29 PM

Proving pressure readings would help! Both while it is cooling and while it is not.

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mk378 on Mon February 10, 2014 9:43 AM

Check if the compressor still engages after it stops cooling.

A common problem is that the clutch gap widens due to wear, when it is too large the clutch plate won't pull in reliably. As the magnet coil behind the pulley heats up, it loses strength, which matches what you say that it works at first when it is cold then quits after warming up.

A simple test for this: after it stops cooling, leave the A/C on and the engine running and go under the hood and hit the clutch plate toward the pulley with a suitable tool, being very careful of the moving parts (On some cars this is simply never going to be safe because of the location of the compressor, but I think your truck has the compressor on top where it is easy to reach). If the gap is the problem it will pull in and start turning and make some cold air, but once it cycles off it will go back to not engaging.

Cussboy on Mon February 10, 2014 1:24 PM

Quote
Originally posted by: mk378
Check if the compressor still engages after it stops cooling.

Yes, great point. I've had this happen on mine, needed to tighten the nut on the AC clutch.

I've also had to clean out oil from the clutch electromagnet surface.

On mine, replaced the AC clutch with a used unit last fall (noisy bearing) without removing or unbolting the compressor, we'll see what how this year's AC season goes with that.

tcrosby2011 on Sun February 16, 2014 3:01 PM

Ok so does anybody have a picture of the part in question? I really have no idea what Im looking at. A
nd if it is the clutch, do I need a whole new condenser or what?

Olds442 on Tue February 18, 2014 3:41 AM

All you have to do is adjust the clutch air gap. No new parts required. Just read one of the previous inquiries on this forum
that tells how to adust.

WyrTwister on Tue February 25, 2014 9:46 AM

Check out youtube . Lots of instructional videos .

Tooling avalable for loan ( with deposit ) at the chain auto parts stores ( like AutoZone & the rest ) .

God bless
Wyr

tcrosby2011 on Wed February 26, 2014 11:21 PM

So are yall sure that it is the clutch air gap?

mk378 on Thu February 27, 2014 7:59 AM

That's my best guess from reading what you said about 400 miles away. You need to actually diagnose the truck.