Air Conditioner Issue

I'm got an issue with my air conditioner working when it feels like it. The issue started last summer and has gotten to the point the air conditioner basically never works. When the issue first started was that I was getting no cold air at all. Whenever I would get the engine up to around 2500 RPM, the air coming out would immediately, not gradually, be cold. For the rest of the trip this air would be cold. Now it has gotten to the point that the air would only be cold if I'm basically going down the interstate at around 80.

My original thought is that the air conditioner itself is working fine, but some door is blocking the cold air since the temp immediately switched. If this was vacuum actuated, the high engine rpm would overcome a leak and open it. I looked for vacuum leaks with no success.

Does anyone have any other ideas for me to check? If you do think its vacuum related, is there anywhere I need to check that isn't under the hood? I've not found a vacuum diagram to use to check I'm looking over all the connections.

I've got a 2000 Silverado LT with a 5.3L

Sounds like your condensor is clogged or pack full of bugs, dirt, etc. You can try rinsing all the dirt etc off of it and see if it improves.

I'm got an issue with my air conditioner working when it feels like it. The issue started last summer and has gotten to the point the air conditioner basically never works. When the issue first started was that I was getting no cold air at all. Whenever I would get the engine up to around 2500 RPM, the air coming out would immediately, not gradually, be cold. For the rest of the trip this air would be cold. Now it has gotten to the point that the air would only be cold if I'm basically going down the interstate at around 80.

My original thought is that the air conditioner itself is working fine, but some door is blocking the cold air since the temp immediately switched. If this was vacuum actuated, the high engine rpm would overcome a leak and open it. I looked for vacuum leaks with no success.

Does anyone have any other ideas for me to check? If you do think its vacuum related, is there anywhere I need to check that isn't under the hood? I've not found a vacuum diagram to use to check I'm looking over all the connections.

I've got a 2000 Silverado LT with a 5.3L

this has no vacuum diagram because there is no vacuum control.

first thing to do is check that the step motor controlled temp door in the air box is working correctly. when placed on cold does the air temp go to cold ? when placed on hot does the air go to hot ?

this is with the ac off ...............

if this works then its in the ac compressor control.

check the low pressure side for 40-50 psi with the ac blower on max , and the doors/windows open ...The engine at 15oo -2,oooRPM.

the air temp of your location should be around 80 deg f when doing this . any lower this is not accurate.

if the compressor cuts out at a pressure above 5psi then you must replace the low pressure cut out switch.

if the pressure at the low side is dropping below 35 psi then you need more R134 refrigerent . if you are low on refrigerent get a 2 oz oil charge of PAG150 TO REPLACE LOST OIL OVER THE LAST 12 YRS. this will reduce future refrigerent losses thru the ac compressor seal. oil lubes and helps seal the system.