GX 470 AC issues (1 Viewer)

[ceylonfj40nut]

i have been chasing down an AC leak on my wife’s gx470. I have done several AC systems before but this one has me stumped.

I have repeatedly charged the system and hit gauge pressures of 45/235 there abouts with r134 after an evac. Charge does not hold for more than three weeks. AC works great when charged.

This weekend I had time to check things out a bit more. I pulled a vacuum for three hours and hit -28 in vac. Tested vac hold. It moved 1 inch in two hours. Confirmed leak. I then charged the system with UV dye and recharged with freon to 45/235 on the gauges. Ran it at 1500 rpm while charging. Ran the car at idle for 15 mins. Shut it down. Came back 4 hours later when dark, put on my UV glasses and checked for leaks with UV light. Checked entire engine bay and there was no visible dye anywhere.

I chased AC lines heading to the rear along PS frame rail all the way to the rear AC unit. No leaks. I checked the condensate coming out of the drain ports for any dye but they were clean.

I then took my electronic sniffer and went through the same areas outside the car described above. No change in audible. Confirmed that there is no leak on the exterior of the truck. I also checked the condensate drains.

I moved into the cabin with sniffer. Only change in audible was through the front vents. Audible signal moved from 0to 3 bars of 10. Indicates small leak of freon in the vent air. No change in sniffer audible in any of the rear AC vents.

Does this mean I have an evaporator leak? Anyone have this issue? Do I have to take the dash off to get at the evaporator?

 

[kbahus]

The rear a/c lines can rust and leak underneath the clamps that hold them to the chassis, this can be difficult to see and detect. Just something else to check.

 

[ceylonfj40nut]

Thanks. Will check.

 

[ceylonfj40nut]

anyone else have similar issues?

 

[GXO]

If it is coming from the vents it is likely the evap core under the dash. Had a rash of replacement on these over on GXOR.

 

[scmcna]

anyone else have similar issues?

On my '09 GX leak was under the dash where the receiver exchanger cools the air . $100 ! part but installation requires dismantling the entire dashboard by a seasoned Lexus mechanic who is patient & likes removing & reassembling many parts. Cost $2k but well worth it. He started with a fluorescent dye test which revealed leak underneath that part. Rear lines were fine.

 

[JeffD]

Mine was leaking above the rear passenger wheel, the connection above/behind the mud flap.