1991 AC leak

[tsr2185]

1991 TBI converted to r134a

What is the best method to find AC leak? I used to vacuum and fill maybe once or twice a year and now it doesn't even last a few days. Holds ~32hg for 30 min. I cannot see pag oil residue anywhere nor in the evap drain line in the firewall. I looked at the evap through the blower motor hole when I changed it out this past winter and damn near looked brand new to me.

Dryer, O rings, orifice tube and condenser about a year old. I even went back and tightened all the fittings again, no change. This south louisiana heat is a killer.

I suspect its the evap but have no proof. My dash would not survive if I tried to replace the evap without knowing for sure that is the culprit, then I would have to buy a new dash.

any input appreciated to narrow down the leak.

 

[man-a-fre]

I'm praying for you that its not your evaporator.

 

[EJ_74]

Have you put any dye in it?

 

[Schurkey]

Beg, borrow, buy an electronic leak detector. Maybe you can get one from the loaner-tool program at a local parts store.

Refrigerant is heavier-than-air, so be certain to test under each component as well as 360-degrees around every O-ring.

I pretty-much refuse to work on an A/C system unless I can replace EVERY O-ring, the desiccant; (accumulator/receiver-dryer) and the orifice tube on CCOT systems. I vacuum the system OVERNIGHT, not just for thirty minutes. That is, I vacuum the system for maybe fifteen or thirty minutes, and then close the valves and shut off the pump, to watch for loss of vacuum overnight.

 

[tsr2185]

I'm praying for you that its not your evaporator.

I fear that is what it is. But i havent confirmed that yet. If it is, its not getting replaced until i have another dash on standby then I will clean the hell out of the hvac box and doors.

Have you put any dye in it?

No i have heard of this but havent looked into it yet. Do they sell freon with dye already in it? Do you need a special light to detect it? Any places/brands you recommend? I have a decent set of guages to work with.

Beg, borrow, buy an electronic leak detector. Maybe you can get one from the loaner-tool program at a local parts store.

Refrigerant is heavier-than-air, so be certain to test under each component as well as 360-degrees around every O-ring.

I pretty-much refuse to work on an A/C system unless I can replace EVERY O-ring, the desiccant; (accumulator/receiver-dryer) and the orifice tube on CCOT systems. I vacuum the system OVERNIGHT, not just for thirty minutes. That is, I vacuum the system for maybe fifteen or thirty minutes, and then close the valves and shut off the pump, to watch for loss of vacuum overnight.

I did replace ALL the orings in the system. The system leaked before and the same after I overhauled it. Just past year started to leak must faster. I pretty much verify theres no major leak in 30 min but apparantly it may be leaking more while the system is running.

Would a leak detector be able to find a leak in evap or condensor, I see that being very difficult? I may be able to find one at our shop....

 

[caminonut]

look at the front of your compressor to see if it is dry, if you have a small leak at the compressor seal, Rub your finger on the center of the compressor where the clutch is and see if you get an oil deposit on your finger if so, you may just need a new seal on the compressor.
Also check your Schrader valves. I have run across slow leaks at the Schrader valve, you can take a little soapy water put on the Schrader valve to see if it bubbles if it does replace the Schrader valve or take it out and clean it.
Make sure after you do that you blow it out so you don’t get any water into the system through the Schrader valve.
And yes, you can buy the 134 a Freon with die in it.

If you’re evaporator is leaking somewhere, it should have an oil stain on it right where the leak is you may have to take your grill out to visually see the whole thing.

 

[RoyBob]

A cheep leak detector will help

 

[tsr2185]

look at the front of your compressor to see if it is dry, if you have a small leak at the compressor seal, Rub your finger on the center of the compressor where the clutch is and see if you get an oil deposit on your finger if so, you may just need a new seal on the compressor.
Also check your Schrader valves. I have run across slow leaks at the Schrader valve, you can take a little soapy water put on the Schrader valve to see if it bubbles if it does replace the Schrader valve or take it out and clean it.
Make sure after you do that you blow it out so you don’t get any water into the system through the Schrader valve.
And yes, you can buy the 134 a Freon with die in it.

If you’re evaporator is leaking somewhere, it should have an oil stain on it right where the leak is you may have to take your grill out to visually see the whole thing.

I did replace the high side schrader valve last month because it had oil residue on it. Didnt change anything. And i had to buy a 25$ kit to find that d4mn thing. I will check the compressor when I fly in tomorrow, thanks.

Is the dye visible to the naked eye, or i need like a blue light to see the dye?

Imma try and find some freon with dye and use soapy water on everything while I run it while the dye does its thing. Sounds like a plan.

Grill, you are referring to condensor i assume.

 

[scott2093]

I couldn't see the leak on my compressor until I pulled it and saw the bottom ...but it was a pretty old compressor....

 

[1998_K1500_Sub]

I couldn't see the leak on my compressor until I pulled it and saw the bottom ...but it was a pretty old compressor....

This ^^^

The R4 compressors (you said it's a 1991) are known to leak, check for leakage around the input shaft and the body of the compressor.

There are YouBoob videos on how to replace the R4's seals, you might take a look at a couple just to familiarize yourself with the leakage paths.

Someone earlier mentioned the service fittings' valves; they can be a problem too but it appears you've checked them (yes?).

If it was leaking at your evap, I would expect to see it coated with dust wherever the oil leaked out of the system onto its fins.