Topping up AC system

[Snagglefoot]

Last fall I fixed a leak in my AC system and was able to verify its proper operation while in the defrost mode on my 2008 Chev Suburban with front and rear AC. I also checked for more leaks, checking all lines and the condenser using a dye marker. I posted all of this last fall on Bitog.

I tried the AC this spring when the temps hit 70 F yesterday. No luck. I checked the pressure it looks like I have 20 psi static pressure on both sides. The AC will not run, probably due to the low pressure switch being activated. I already changed the system to R12A which is a hydrocarbon based refrigerant legal in Canada that has no restrictions regarding capture. Seeing that it took 5 months to go from 40 psi to 20psi I’m planning on loading another canister of R12A to bring the pressure up. Is anyone else nursing along a leaky AC system? Is a 20 psi loss in 5 months a liveable situation on a beater? I’ll try to find the leak but I’m not too optimistic about it. Any thoughts? Thanks. Here are some shots from last fall.

 

[atikovi]

If all I had to do was add a can, even 2 or 3 cans per year to have cold A/C, I wouldn't even think about it.

 

[demarpaint]

Since you already added dye and it had the entire winter to leak out, did you break out the black light and have another look? It could be an easy fix. If not top it up and call it a day since it is a beater.

 

[atikovi]

I’ll try to find the leak but I’m not too optimistic about it. Any thoughts?

Compressor body or shaft seal?

 

[repairman54]

Compressor body or shaft seal?

2x was typing that when you posted. Especially on an old compressor that may have a slipping clutch putting heat into the front seal.

 

[Chris142]

Compressor body or shaft seal?

Or evaporator or condenser etc. 2 common leak points on that truck.

Iirc it holds about 3 lbs of refrigerant. That's a huge leak and should be easy to find.

Also needing ac @ 70 degrees lol.

 

[Bear]

InterDynamics A/C Pro ACP-102 Ultra Synthetic A/C Recharge R-134a Car Refrigerant - 12 OZ​

This is what I used last year on my 2014 F150. We had "hot' weather two weeks ago and I still have 42F air coming out

 

[mk378]

Dye rides with the oil, it doesn't come out of leaks much unless the system is charged up and running.

HC refrigerant can be detected with a flammable gas leak detector but there tend to be a lot of false alarms on a car.

 

[RooflessVW]

Or evaporator or condenser etc. 2 common leak points on that truck.

Iirc it holds about 3 lbs of refrigerant. That's a huge leak and should be easy to find.

Also needing ac @ 70 degrees lol.

He said tried it, not needed it.

And I love when you desert folk visit the Right coast. 90 in NC will have you begging to go back to the desert.

 

[spasm3]

Also needing ac @ 70 degrees lol.

Its more humid than where you are. Need a/c to keep the windows from fogging up, esp in the rain.

 

[atikovi]

Dye rides with the oil, it doesn't come out of leaks much unless the system is charged up and running.

HC refrigerant can be detected with a flammable gas leak detector but there tend to be a lot of false alarms on a car.

It's pretty easy to see on my Saturn compressor.

And a flammable gas leak detector? I don't think those have been used since the 50's. You do know that burning freon creates deadly phosgene fumes?

 

[demarpaint]

Dye rides with the oil, it doesn't come out of leaks much unless the system is charged up and running.

HC refrigerant can be detected with a flammable gas leak detector but there tend to be a lot of false alarms on a car.

This is true, but the AC was used last season, it had plenty of time to find its way out. The OP has a pretty big leak it should be easy to find as others mentioned.

 

[Cujet]

My guess is that 20PSI means the system is nearly empty. Propane/butane will produce a set pressure, based on temperature, until the liquid is gone.

 

[brianl703]

And I love when you desert folk visit the Right coast. 90 in NC will have you begging to go back to the desert.

So will getting swamp ass just from walking to the mailbox due to that east coast humidity.

 

[Chris142]

It's pretty easy to see on my Saturn compressor.
View attachment 153372

And a flammable gas leak detector? I don't think those have been used since the 50's. You do know that burning freon creates deadly phosgene fumes?

My electronic AC leak detector will work on flammable gasses too.

 

[KrisZ]

I absolutely would. But I would try to find and fix the leak eventually because it will probably only get bigger over time.

 

[mk378]

Propane/butane will produce a set pressure, based on temperature, until the liquid is gone.

"R12a" is a mixture and it will fractionate in a leak situation, with the more volatile component (propane) leaving first. Thus it should all be removed and replaced with new to ensure the proper mixture.

The detector used by gas fitters to detect leaks. This is less expensive than a refrigerant detector and also more sensitive to HC since that is what it is designed to detect.

https://www.amazon.com/Portable-Combustible-Detector-Methane-Propane/dp/B0871KX5MF/

 

[Nukeman7]

I have this freon leak detector and it works quite well. Currently on sale for a killer price on Amazon.

 

[Snagglefoot]

"R12a" is a mixture and it will fractionate in a leak situation, with the more volatile component (propane) leaving first. Thus it should all be removed and replaced with new to ensure the proper mixture.

The detector used by gas fitters to detect leaks. This is less expensive than a refrigerant detector and also more sensitive to HC since that is what it is designed to detect.

https://www.amazon.com/Portable-Combustible-Detector-Methane-Propane/dp/B0871KX5MF/

Yep, this is the one I have and is perfect because my R12A is essentially propane, which is legal in Canada in auto AC systems.

 

[Snagglefoot]

Well dang. I found the dye leak. Surprisingly its at the same place as last time, even though I replaced the seal. It’s where the high pressure line enters the evaporator. I had used the HC Sniffer with it running after the original repair and did not detect anything. We had temps down to 0 F this winter so I’m wondering it that’s when it let go. Also wondering if I have corrosion or a crack in the evaporator itself. Here’s a shot showing the green dye.