Air Conditioning Issues
Thread Starter
Melting Slicks
Joined: Dec 2006
Posts: 2,308
Likes: 104
From: Orange County California
When using a sniffer:
Also shows up at the vents when the fan is first started which blows it out from the evap chamber.
UV light is the easiest and cheapest way for most and a good starting point. Only shows up on the drain tube and not the vents. Also shows up at all the under hood AC components.
In the 'old' days we would just add a can of R12 and watch for the bubbles to disappear from the sight glass on the receiver.
Also shows up at the vents when the fan is first started which blows it out from the evap chamber.
UV light is the easiest and cheapest way for most and a good starting point. Only shows up on the drain tube and not the vents. Also shows up at all the under hood AC components.
In the 'old' days we would just add a can of R12 and watch for the bubbles to disappear from the sight glass on the receiver.
So, from your post, are you saying the refrigerant can even show up from the air vent when the fan is first started, even if the evaporator coil is still good? When the guy sniffed the air vent and it detected refrigerant, he had just filled the system with refrigerant. There were no sniffed leaks under the hood, even underneath the car's engine compartment. Only from the air vents. I'm about to get a top-notch Chevy dealer who has experience yanking Corvette dashboards (when I went there a few weeks ago, they were yanking a C8 dash out due to needing an entire wiring harness replaced due to rodent damage), but I'm wanting to make sure before THEY diagnose it, whether there could be other sources of the leak.
Thanks.
Melting Slicks
Joined: Feb 2018
Posts: 2,199
Likes: 1,057
From: North Texas
Oh, the good old days! Have recharged many R12 systems back then.
So, from your post, are you saying the refrigerant can even show up from the air vent when the fan is first started, even if the evaporator coil is still good? When the guy sniffed the air vent and it detected refrigerant, he had just filled the system with refrigerant. There were no sniffed leaks under the hood, even underneath the car's engine compartment. Only from the air vents. I'm about to get a top-notch Chevy dealer who has experience yanking Corvette dashboards (when I went there a few weeks ago, they were yanking a C8 dash out due to needing an entire wiring harness replaced due to rodent damage), but I'm wanting to make sure before THEY diagnose it, whether there could be other sources of the leak.
Thanks.
So, from your post, are you saying the refrigerant can even show up from the air vent when the fan is first started, even if the evaporator coil is still good? When the guy sniffed the air vent and it detected refrigerant, he had just filled the system with refrigerant. There were no sniffed leaks under the hood, even underneath the car's engine compartment. Only from the air vents. I'm about to get a top-notch Chevy dealer who has experience yanking Corvette dashboards (when I went there a few weeks ago, they were yanking a C8 dash out due to needing an entire wiring harness replaced due to rodent damage), but I'm wanting to make sure before THEY diagnose it, whether there could be other sources of the leak.
Thanks.
The refrigerant if it is leaking from the evaporator core will not show up in the engine compartment, but will show up in that area at the drain tube itself
So when the technician monitored for a leakage of refrigerant at the vents, he was doing it correctly if he turned on the fan, but like I said, the refrigerant is heavier than air so it settles to the bottom of the fan box itself, and that’s where the drain tube is and that’s thus where you can monitor it from underneath the car
Usually, you cannot see the UV at the vent, but it should show up if it’s a major leakage at the drain tube
Last edited by Tinkertech; Mar 12, 2026 at 08:19 AM.
Team Owner
Joined: Jul 2004
Posts: 28,502
Likes: 3,302
From: Hartford WI
I'm about to get a top-notch Chevy dealer who has experience yanking Corvette dashboards (when I went there a few weeks ago, they were yanking a C8 dash out due to needing an entire wiring harness replaced due to rodent damage), but I'm wanting to make sure before THEY diagnose it, whether there could be other sources of the leak.
Thanks.
Thanks.
Melting Slicks
Joined: Feb 2018
Posts: 2,199
Likes: 1,057
From: North Texas
Air conditioners are really simple to work on, except the evaporator because you need to pull the dash.
Most DIY's don't have the knowledge or the equipment $$$ to do it right.
Note: Your $20 Walmart can of refrigerant with the cheese dial ainta gonna work.
Most DIY's don't have the knowledge or the equipment $$$ to do it right.
Note: Your $20 Walmart can of refrigerant with the cheese dial ainta gonna work.
Team Owner
Joined: Jul 2004
Posts: 28,502
Likes: 3,302
From: Hartford WI
IMO, the can of refrigerant is a great thing to use to sell the car. For the buyer, not so much. For the mechanic to fix, it's good. I guess, as the song goes, "Two out of Three ain't bad".
Melting Slicks
Joined: Feb 2018
Posts: 2,199
Likes: 1,057
From: North Texas
You don't need the 'machine' that dealerships use.
All you need is all the separate pieces of equipment:
Set of good gauges with quality hoses.
Vacuum pump 1-5 CFM.
Leak detector, a quality one.
UV light.
Weight scale that can measure down to the tenth of an ounce.
DVM.
20Lb jug of the correct type of refrigerant.
An optical RPM gauge to measure fan speed.
And if your at the top of your game, a tank of nitrogen and an appropriate sniffer.
Don't forget the 'bubbles'.
I'm sure I've left something out but this is a good start!
Oh, I forgot the most important item, KNOWLEDGE. Without this one item you're never gonna make it, at least correctly.
All you need is all the separate pieces of equipment:
Set of good gauges with quality hoses.
Vacuum pump 1-5 CFM.
Leak detector, a quality one.
UV light.
Weight scale that can measure down to the tenth of an ounce.
DVM.
20Lb jug of the correct type of refrigerant.
An optical RPM gauge to measure fan speed.
And if your at the top of your game, a tank of nitrogen and an appropriate sniffer.
Don't forget the 'bubbles'.
I'm sure I've left something out but this is a good start!
Oh, I forgot the most important item, KNOWLEDGE. Without this one item you're never gonna make it, at least correctly.
Team Owner
Joined: Jul 2004
Posts: 28,502
Likes: 3,302
From: Hartford WI
You don't need the 'machine' that dealerships use.
All you need is all the separate pieces of equipment:
Set of good gauges with quality hoses.
Vacuum pump 1-5 CFM.
Leak detector, a quality one.
UV light.
Weight scale that can measure down to the tenth of an ounce.
DVM.
20Lb jug of the correct type of refrigerant.
An optical RPM gauge to measure fan speed.
And if your at the top of your game, a tank of nitrogen and an appropriate sniffer.
Don't forget the 'bubbles'.
I'm sure I've left something out but this is a good start!
Oh, I forgot the most important item, KNOWLEDGE. Without this one item you're never gonna make it, at least correctly.
All you need is all the separate pieces of equipment:
Set of good gauges with quality hoses.
Vacuum pump 1-5 CFM.
Leak detector, a quality one.
UV light.
Weight scale that can measure down to the tenth of an ounce.
DVM.
20Lb jug of the correct type of refrigerant.
An optical RPM gauge to measure fan speed.
And if your at the top of your game, a tank of nitrogen and an appropriate sniffer.
Don't forget the 'bubbles'.
I'm sure I've left something out but this is a good start!
Oh, I forgot the most important item, KNOWLEDGE. Without this one item you're never gonna make it, at least correctly.
Can the machine be rented instead of trying to get a bunch of pieces of equipment to work together?
Melting Slicks
Joined: Feb 2018
Posts: 2,199
Likes: 1,057
From: North Texas
I'm sure you could rent one but I never heard of this approach and I would expect it would be expensive. They're big and heavy, they won't fit inside the trunk of your Toyota. Also you would need a jug of refrigerant.
But then again, you would need the knowledge on troubleshooting and recharging AC systems or you're just wasting time and money.
My advice is find someone that knows what they're doing, a friend or repair shop, that is equipped to repair the system.
But then again, you would need the knowledge on troubleshooting and recharging AC systems or you're just wasting time and money.
My advice is find someone that knows what they're doing, a friend or repair shop, that is equipped to repair the system.
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Thread Starter
Melting Slicks
Joined: Dec 2006
Posts: 2,308
Likes: 104
From: Orange County California
Almost in the shop. Diagnosed (2nd time...the shop would not do it unless they did hte diagnosis) and scheduled for dash R/R. $3000. SoCal.
Thanks for all the info.
Thanks for all the info.