AC Leak - Where should I look?

[Larry07Yukon]

Truck is a 2007 Yukon Denali XL

I clearly have an AC leak somewhere. In mid April the AC quit blowing cold air, being a cool spring I recharged the system in early May and it went strong for about a month. This past weekend it completely went out again.

I took it to the mechanic today and they recharged the system with refrigerant with a dye. They inspected the compressor, condenser, fittings, lines, etc and stated they could not find a leak. They said to drive around for a few weeks and if it goes out again to come back.

Are there any common areas for these trucks to leak that aren't immediately visible? Any recommendations?

I don't believe it matters, but over the winter I changed the heater hose (the one with the stupid plastic Y connector). Anyway, since the hose completely cracked off, I was having a hard time removing the remnants of the hose and was jerking around in the area. The AC condenser is right next to it, but I don't think I did anything to it.

I should note I don't drive the truck very often, about 1-2 a week.

 

[kbuskill]

Could be rear evaporator leaking which is inside the passenger side rear panel by the tailgate.

You would have to pull the panel and look in there with a black light/UV light.

 

[DSN46]

Could be rear evaporator leaking which is inside the passenger side rear panel by the tailgate.

You would have to pull the panel and look in there with a black light/UV light.

+1 on this. I had to have the rear evaporator replaced along with the expansion valve in the rear of my Suburban.

 

[Larry07Yukon]

+1 on this. I had to have the rear evaporator replaced along with the expansion valve in the rear of my Suburban.

Could be rear evaporator leaking which is inside the passenger side rear panel by the tailgate.

You would have to pull the panel and look in there with a black light/UV light.

Thanks for the quick responses. I’ll pull the rear panel this week to see if there is dye everywhere. I followed the lines to the rear yesterday and I don’t see any leaks in the hard lines (which I guess might be good)

Hopefully it’s just that expansion valve, I’d imagine that is one of the less expensive repairs.

 

[Larry07Yukon]

Still trying to track down this leak. Took it to a mechanic, recharged the system with dye. I found a small leak at the pressure sensor. Mechanic changed sensor and o-ring and recharged...few weeks later AC was down again

Took it back, they claimed to replace the high side valve core...few weeks later AC was down again

I took the trunk apart, inspected everything back there and bone dry, not a single sign of dye around the rear evaporator or expansion valve.

I bought a new red "dye" and will recharge the system myself. Anywhere else I should be looking?
Is there anything behind the dashboard that could be leaking? This is really driving me nuts

Good news is all components seem to be working. Does anyone have a diagram of the system? Maybe I'm not following all the piping paths?

This truck has so many little annoying problems

 

[kbuskill]

Still trying to track down this leak. Took it to a mechanic, recharged the system with dye. I found a small leak at the pressure sensor. Mechanic changed sensor and o-ring and recharged...few weeks later AC was down again

Took it back, they claimed to replace the high side valve core...few weeks later AC was down again

I took the trunk apart, inspected everything back there and bone dry, not a single sign of dye around the rear evaporator or expansion valve.

I bought a new red "dye" and will recharge the system myself. Anywhere else I should be looking?
Is there anything behind the dashboard that could be leaking? This is really driving me nuts

Good news is all components seem to be working. Does anyone have a diagram of the system? Maybe I'm not following all the piping paths?

This truck has so many little annoying problems

It's possible that the evaporator behind the dash is leaking. I would get under the truck at night or in a garage with the door closed and use a UV/black light to search for the dye. If you suspect it's leaking from the evaporator behind the dash then pay particularly close attention to the drain where the condensation drips out and see if you can locate any of the dye around there.

 

[Larry07Yukon]

It's possible that the evaporator behind the dash is leaking. I would get under the truck at night or in a garage with the door closed and use a UV/black light to search for the dye. If you suspect it's leaking from the evaporator behind the dash then pay particularly close attention to the drain where the condensation drips out and see if you can locate any of the dye around there.

Thanks, I've spent many late nights crawled under the truck looking for traces of dye...no luck so far.

I'm hoping this red "dye" like stuff is easier to locate.

 

[kbuskill]

Thanks, I've spent many late nights crawled under the truck looking for traces of dye...no luck so far.

I'm hoping this red "dye" like stuff is easier to locate.

We're you using a UV/black light??? The green glows pretty good when the light hits it.

 

[Larry07Yukon]

We're you using a UV/black light??? The green glows pretty good when the light hits it.

Yes, the shop used the green dye. I found it at the pressure sensor so I know what it looks like...but can't find more of it elsewhere. (using blacklight and the yellow glasses)

Pressure sensor replaced, few weeks later refrigerant was out.
Valve core replaced, few weeks later refrigerant was out.

 

[swathdiver]

Yes, the shop used the green dye. I found it at the pressure sensor so I know what it looks like...but can't find more of it elsewhere. (using blacklight and the yellow glasses)

Pressure sensor replaced, few weeks later refrigerant was out.
Valve core replaced, few weeks later refrigerant was out.

So what has happened since Larry?

 

[MikeM Daly City]

Exact same issue, 2000 Tahoe Z71. Interested in any follow up

 

[swathdiver]

Exact same issue, 2000 Tahoe Z71. Interested in any follow up

Mine was leaking at the lower fitting on the condenser. I replaced the gasket and it still leaked and then stopped after a few days. Then we put the new bumper on and the AC is still blowing cold. When it doesn't, the dealer can fix it.

 

[Miami-Dade]

So what has happened since Larry?

Exact same issue, 2000 Tahoe Z71. Interested in any follow up

Unfortunately Larry left the building October 24 2018.

 

[swathdiver]

Unfortunately Larry left the building October 24 2018.

Do you mean passed away or just hasn't returned? If the latter, I often check the date of their last visit and hope that maybe they'll get an email alerting them to an old thread of theirs and come back and contribute. Sometimes it works.

 

[Kev 05 Tahoe]

Has anyone else had this problem with the AC leaking at evaporator and cant find it? im in the same boat with the leak problem but cant find it with the UV light. Can anyone help with experience?

 

[elmarave20]

Hello everyone I've been trying to look for the darn leak myself on my 2008 Yukon 6.2 Denali, I changed the pressure switch I changed the valve on the low side port, I haven't changed the valve on the high, I took it to the dealership prior , I was told the low side valve on the port is leaking and the pressure switch, I changed it and nothing. I have to put a can of freon every week. I will check the panel on the back I was not aware there was something there, I will continue to fix the issue.. I also did a vacuum test and left it over night the gauge never drop , it must be a very very slow leak...