AC gurus: what is this part?

[gakattack]

Driving home today, I noticed that my AC no longer blows cold. The AC light illuminates solid on the fan switch, checked all fuses in the footwell and in the engine bay, all are good. Noticed I didn't hear the relay click and the clutch is not engaging.

Checked both the low and high sides and noticed that this black plastic piece on the high side is oily. What is this piece called and what does it do? Also checking the window on the high side, I vaguely recall seeing green in here previously but it's empty. Do these trucks have a safety mechanism to prevent the compressor clutch from engaging when refrigerant/oil is low?

 

[Humble Leader]

ok so you have a freon leak and the hardest part seems to be done. you've found the (hopefully only one) leak. the vehicle will stop the AC compressor from running when freon is low to prevent damage to the compressor. you will see this in short cycling. compressor on and off every few seconds

only when the freon is really low will the compressor stop cycling. that piece looks like a connector on the high side. if your compressor wouldn't go on you probably have almost no freon especially if all vents are warm

 

[gakattack]

ok so you have a freon leak and the hardest part seems to be done. you've found the (hopefully only one) leak. the vehicle will stop the AC compressor from running when freon is low to prevent damage to the compressor. you will see this in short cycling. compressor on and off every few seconds

only when the freon is really low will the compressor stop cycling. that piece looks like a connector on the high side. if your compressor wouldn't go on you probably have almost no freon especially if all vents are warm

You nailed it on the head. Ended up taking it to the shop and they found that one of the gaskets ended up failing. They fixed that and recharged, good as new.

 

[Humble Leader]

You nailed it on the head. Ended up taking it to the shop and they found that one of the gaskets ended up failing. They fixed that and recharged, good as new.

thats great news. I would make sure the repair will hold and I'd check vent temps and monitor the AC cycling. you want to make sure driver left centre vent and max cold low-med fan speed is 40-45F with recirc on

 

[Ezlife45]

That pic looks like an old school sight glass so you can check for air/gas bubbles when the liquid passes the sight glass.