A/C blows too cold? over cycling? Help!

[braud26]

I don't recall this happening when my 2006 kia spectra was new. The a/c blows at 50 to 55 degrees in the vents at idle with no cycling. When I drive on the highway the a/c cycles on and off. It cycles off at 43F and cycles on at about 48F and it is 95 degrees out side. This cycling happens about every 6 to 10 seconds. I have 3 other vehicles that i tested and do not do this. They stay around 38F degrees with no cycling. I noticed this cycling pattern when my compressor went bad but it still worked.I replaced the expansion valve, compressor and condenser. I flushed the lines and evaporator and vacuumed it and charged it to speck. What could be causing this over cycling at highway speeds?

[Dougflas]

you could be a few ounces low on refrigerant. Compressor does not put out as much at idle as when cruising. I would add a few oz of refrigerant.

[braud26]

my service tag under hood shows 475~525g of refrigerant for charge. i tried that theory before this last charge. i put 511g=18.025 ounces and weighed it to speck. so thinking what you were thinking "add more". I started to charge more into it and when i got to 19 ounces it started to cycle every 4 to 5 seconds at idle. so i know it was to much. so did a recovery and recharged back to 18 ounces.

[Cusser]

The a/c blows at 50 to 55 degrees in the vents at idle with no cycling. When I drive on the highway the a/c cycles on and off. It cycles off at 43F and cycles on at about 48F and it is 95 degrees out side. What could be causing this?

I'm not sure that there is actually an issue here, think I'd leave it as is, sounds like it cools normally. Idle is less rpm and no air ramming over the condenser, will not be expected to put out as low temperature as when moving.

[Dougflas]

If it cycles every 6 to 10 seconds, your clutch won't last very long.

[braud26]

Its 96 degrees here in texas today. i dont think its normal to cycle at these temps outside. I dont know if this helps but last night it was 73 degrees out and I put the gauges on and my pressures read .low side would drop to 31 and stay there till high would rise to 200 then cycle off at idle. is high side getting to high?

[braud26]

If it cycles every 6 to 10 seconds, your clutch won't last very long.

Thats why i think somthing is not right

[Dougflas]

You need to run the engine at 1500 rpm, doors/windows open, max fan speed/max cool; then give it time to stabilize and post your temps and pressures.
Make sure the radiator is clean. I do not have a schematic or this vehicle to check the control system.

[braud26]

You need to run the engine at 1500 rpm, doors/windows open, max fan speed/max cool; then give it time to stabilize and post your temps and pressures.
Make sure the radiator is clean. I do not have a schematic or this vehicle to check the control system.

Ok did what you said and this is what I came up with. The temp out side is 83f degrees. My pressure reading are low 41 high 220. The inside vent blows at 57f degrees. This is all with windows and doors wide open and at idle after running it at 1500 rpms.
later I started to think maybe you need the readings at 1500 rpms so here they are at 1500 rpms. low 31 high 260 with out side temp 78f degrees.

[Dougflas]

High side is a tad high. I would begin looking at the controls. If you do not have a schematic, you can purchase a vehicle specific CD from Mitchell or All Data I believe.