A/C not working, suspect leaking refrigerant

[jollyjerry]

I replaced the low pressure valve because I saw that it was leaking after I put in some UV dye. I didn't see any other areas under the hood that was leaking. After a recharge last week (read 30psi on the low side in ~70F), the compressor consistently engaged, and cold air was blowing.

Over the weekend, in 90F+ heat, the AC stops working, and it looks like it's low on refrigerant again. I noticed that there was chilled air coming out when I started the truck even with the AC off.

Could refrigerant be leaking in the cabin after it enters through the firewall? Is there a diagram for this? Am I missing anything thing else?

 

[4D2Envy]

Using a UV light and some glasses or just eye balling?

 

[whiplash473]

Could also be a leak in the condenser, not too easy to see.

 

[jollyjerry]

Using a UV light and some glasses or just eye balling?

Yep, UV light in the dark

Could also be a leak in the condenser, not too easy to see.

I didn't see a leak in the fittings going into the condenser. The condenser as a whole looks to be in pretty good shape, so I think the previous owner replaced it at some point.

Friend suggested that his compressor clutch didn't have enough friction material to engage, I'll check that out today. Haven't driven it since my trip back.

 

[4D2Envy]

Is the AC clutch going through its normal cycle?

Edit: I'm an idiot just read that the clutch is working. Youll have to hook it up to a machine again and see what the pressures are at and how they change while it's going through its cycle.

 

[Fuzzy]

I replaced the low pressure valve because I saw that it was leaking after I put in some UV dye. I didn't see any other areas under the hood that was leaking. After a recharge last week (read 30psi on the low side in ~70F), the compressor consistently engaged, and cold air was blowing.

Over the weekend, in 90F+ heat, the AC stops working, and it looks like it's low on refrigerant again. I noticed that there was chilled air coming out when I started the truck even with the AC off.

Could refrigerant be leaking in the cabin after it enters through the firewall? Is there a diagram for this? Am I missing anything thing else?

Yes it is possible that refrigerant is leaking at the evaporator inside the HVAC box. If you don't see a leak around any of the fittings inside the engine compartment or around the belly of the compressor then that's probably where your leak is.