A/c won't cool.

Replaced water pump and thermostat working great
Replaced the compressor, drier, condenser and Schroeder valve
Filled to 35 psi, tested, added to 40 psi, tested, added to 45 psi tested.. no cool
Checked all circuit breakers

What the heck could I be missing here? I've replaced pretty much everything in the a/c system.

 

Overfilling it will degrade performance as well. If the compressor is running, and pressures are correct, might be time to check and see if the temp door in the heater box hasn't broken.

 

TYVM! That's what I was thinking of looking at next.

 

Something like a bore scope would make it easier.... Don't have to disassemble it..... I think you can actually rent one from the various parts stores.

 

Great... i'll try that first.

 

40lbs? I'm hoping you mean psi and not that you put 40lbs in the system as that would be way overcharged. Our system only holds 32oz (2 lbs).

The correct way to charge a system is by weight and not based off of pressure readings. You really need a scale to be able to charge it properly. If you overcharge it, it can not only be dangerous, but it won't cool either. If you're going to charge it based off of pressure, you also need gauge that read pressures on the high and low side, but just the low side like most auto parts cans come with. You may already have this, I don't know, but most people don't. I wish the parts stores didn't even sell the cans of r134a because people cause way more harm than good by using those refill kits.

If you've got all of that covered, did you pull a vacuum on the system? You want to pull a vacuum of at least 29hg for at least 30 minutes (I do an hour) before charging the system. This pulls all of the moisture out and without doing it, you'll have a hard time getting great cooling.

You can also leave a vacuum on it overnight to check for leaks. If it leaks down you have a leak somewhere.

I'm also assuming that you added the correct amount of oil? Too much oil will degrade the performance as well. As will not enough (that'll likely lead to component failure).

If you did all of that, it's charged properly, and it's still not working I'd make sure the compressor is coming on. If it's not, I'd check the power and check the switches.
​​​​If it is, make sure your blend door is working correctly.

Also, this won't affect your cooling, but may help. If your compressor failed you'll likely have metal shavings throughout the rest of the system. You need to flush the evaporator core and the lines to get this metal out. You'll also need to replace the expansion valve, drier, and condenser. If you don't, you'll likely end up with the compressor failing again relatively quickly.


If you find you have a leak that you can't find, it'll probably be in the evaporator core. Those leak often on these trucks.


If you have any other specific questions, I'll be glad to try to answer them for you.

 

psi + pounds per square inch BUT i changed it in my original post so as not to confuse. I will take it in and have the shop pull the vacuum just to be sure.. i have done everything else except the blend door.. tyvm for your advice...

 

If you didn't pull a vacuum before charging the system, you will likely not have optimal A/C cooling. I always pull a vacuum anytime the system has been opened to air. My low side pressure usually runs between 28 - 32. Once a vacuum has been pulled on the system, charge it with the weight of R-134a specified on the underhood sticker. As was mentioned, also be sure to check the blend door and vacuum hoses/check valve at the intake manifold to ensure there are no vacuum leaks/blockage there.

 

TYVM! so much for DIY on the a/c... I have learned a lot though and glad I tackled it myself.. I will work on pulling a vacuum, and checking the blend door and the rest.

 

You can pull the vacuum on the truck's A/C system yourself. All you need is a set of A/C gauges, manifold, hoses and a vacuum pump. Harbor Freight sells them all at very reasonable rates. If you can pull a vacuum of 28.5 (reading on the low side gauge) and not have it creep back due to a possible leak in the system, then you are good to charge up the system with R-134a.