I was looking at changing out my low pressure AC switch because my lines are icing to the point they restrict airflow when running the AC but ran into a problem.

The parts shop tells me that there is no schrader valve behind the low pressure switch on my model (04 F150 FX4 5.4 new style), so they can't sell me the switch unless I have a licence to handle the refrigerant.

Can anyone confirm if there is a valve or not behind this switch?

Thanks

 

You sure you aren't just undercharged?

 

Not 100%. I only have a low side gauge and I added some refrigerant last summer because my compressor was short cycling.

The low side is sitting around 30 psi, maybe 25 at 1500 to 2000 rpm. I have been trying to track down some high side gauges but haven't been able to yet. I didn't want to overcharge it and cause any damage.

Shops around here won't just check the pressures, they want to evacuate it and do a draw down test. I really didn't want to spend that kind of cash on it right now. I've already replaced the engine and it still isn't running right.

 

Just an update, I checked the low side pressures again this weekend to see what was up. I am sitting at 35PSI at idle and about 27 - 30 PSI at 2000 RPM. It wasn't icing up yesterday either, but the ambient temperature was only 15 degrees C.

 

I think you are undercharged, but the only way to positively tell is evacuate the system and recharge with the exact weight refrigerant. A high side gauge will tell a better story, but still not that definitive.

 

I was trying to find the exact charge the system calls for. That sticker on my truck is destroyed and you can't read the charge amounts. I will check the pressures again on a warmer day if I notice any icing issues.

 

37 ounces/1049 grams.