AC Problem

Okay folks, newbie here. I have a 99 Blazer 4.3 L with an AC problem. I just replaced the Compressor, new seals on the lines going into the compressor and charged my system (about 23 oz of 134a).
The compressor is a waranteed (90 day) used from an S15 GMC, same engine type. The compressor seems to be short cycling on and off, and is not blowing really cool air, slightly below outside temp.
Is this a clutch problem, a switch problem or is the compressor still bad? Is it something I haven't thought of? The truck has 110K on it, but I love it. I spend a lot of time in it every day, and would really like a break from the heat of August in Central Maryland.
Any help is appreciated, thanks.

Take a gauge and test the system pressure with the AC and fan on max.

You probably have low refrigerant.

Thanks, I'll give it a try.

Okay folks, newbie here. I have a 99 Blazer 4.3 L with an AC problem. I just replaced the Compressor, new seals on the lines going into the compressor and charged my system (about 23 oz of 134a).
The compressor is a waranteed (90 day) used from an S15 GMC, same engine type. The compressor seems to be short cycling on and off, and is not blowing really cool air, slightly below outside temp.
Is this a clutch problem, a switch problem or is the compressor still bad? Is it something I haven't thought of? The truck has 110K on it, but I love it. I spend a lot of time in it every day, and would really like a break from the heat of August in Central Maryland.
Any help is appreciated, thanks.

We will all assume that you evacuated the system with a vacuum pump prior to filling with 134a. Make sure that that your wire connections to the switches are connected and not loose, espescially the one on the accumulator. If all is o.k. I'd do what BlazerLT says and probably add a little more 134a.