99 LX470 AC Leak Help

[YodaQuoia]

Time to start my own thread after a couple weeks of reading. 99 LX470 about to roll over to 300k. I’ve had a slow AC leak for a while. Last summer I added a cal of stop leak and that got me through most of the season. I topped it off this winter because it wasn’t defrosting very well but figured I’d be making some repairs this year. I added UV dye last weekend and R134a up to 30psi on the low side. Went for about a 30 minute drive with max AC blowing nice and cold. Next day it was down to about 10 psi and blowing luke warm.

I got out the black light and started searching. I located a small about of tiny “splatter dots” on the front passenger floor board under the evaporator area. Searching all other lines, vents, etc I couldn’t find any other dye. Figured it’s the evaporator/expansion valve.

However I pulled the evaporator cover this morning and I can’t see any UV dye inside the body. The cover seal felt nice and tight. I already ordered parts but before I dig in, are there any thoughts on where else that dye could have come from? Passsenger floor duct? That does point at the spot where the majority of the dye is.

Any other diagnostic or leak detection tricks out there?

 

[2001LC]

Seeing green on floor mat and not on/in bottom of HVAC box. May be a false green (not the dye), on floor mat.
You would have, very likely seen. Water dripping on floor mat, when AC run. This is from a bad seal in face plate and clogged drain. If seal good. Green dye could not have dripped onto floor mat. Unless drain clogged, and water level in box rose over 6 ". You then, see a lot of green dye in and on HVAC housing and filters.

Did you check for dye:
Pipe going from RH front fender-well along frame to rear AC.
Drain at rear AC.
Compressor.
Condensor.

Check H & L ports, with soap water.

You can try a refrigerant sniffer.

Slow leaks tend to be at compressor. These can be hard to find. But with good eyes, in dark condition (night or in shop) with good strong UV light. We'll see dye specks con compreesor.

Pipes just back of RH front fender-well. Very common leak!

 

[YodaQuoia]

Thanks 2000LC. First paragraph supports my theory that I was heading down the wrong road. Just buttoned that back up.

I’m highly confident there are no leaks in the passenger side piping. I know these are common but I’ve checked repeatedly for those and the rear drain. No signs of dye.

I’ve checked the condenser fittings and along the bottom - didn’t see anything but only check once.

Compressor I haven’t taken a good look at. I’m due for an oil change so I’ll poke around when I’m underneath with the skid plate off.

H&L ports I’ve just checked for dye. Cleaned the L port good after putting the dye in and still nothing there so far.

So you’ve got me thinking compressor which of course ain’t cheap. Do you know any tests you can perform to check it vs just visual inspection for dye?

 

[2001LC]

Thanks 2000LC. First paragraph supports my theory that I was heading down the wrong road. Just buttoned that back up.

I’m highly confident there are no leaks in the passenger side piping. I know these are common but I’ve checked repeatedly for those and the rear drain. No signs of dye.

I’ve checked the condenser fittings and along the bottom - didn’t see anything but only check once.

Compressor I haven’t taken a good look at. I’m due for an oil change so I’ll poke around when I’m underneath with the skid plate off.

H&L ports I’ve just checked for dye. Cleaned the L port good after putting the dye in and still nothing there so far.

So you’ve got me thinking compressor which of course ain’t cheap. Do you know any tests you can perform to check it vs just visual inspection for dye?

Visual for dye and or a sniffer.

Note:
A slow leak, at compressor. Is very hard to find. These leaks often give false good results, during vacuum test. They're a leak, that result in need to charge every 1 or 2 years.

A system needing charge, the next day. Is a bad leak. The dye should be very easy to spot.