AC Leak (somewhere)

[DavidW]

1996 Ford Ranger 4WD, 6CYL, 4.0.
I had the AC serviced last year (added freon) and all worked well for abt 2 weeks (COLD AIR). Over time, it depleted. I ran a dye and light all over the engine compartment but could not find a leak. Any suggestions on where to look before I invest again. Thanks.

 

[RonD]

The condenser, in front of radiator, is high pressure and can be hit by road debris.

The Evaporator in the heater box can't be seen easily, less likely to leak, but did you take the cover off of it?

An AC/refrigeration guy, car or home, will have a "Freon" sniffer that can locate leaks easier, and in the long run it may be cheaper to pay someone to find it, then you can replace the line or part that's leaking
You could check if anyone rents one of these sniffers

 

[DavidW]

The condenser, in front of radiator, is high pressure and can be hit by road debris.

The Evaporator in the heater box can't be seen easily, less likely to leak, but did you take the cover off of it?

An AC/refrigeration guy, car or home, will have a "Freon" sniffer that can locate leaks easier, and in the long run it may be cheaper to pay someone to find it, then you can replace the line or part that's leaking
You could check if anyone rents one of these sniffers

Thanks for the reply. All the AC Tech used was a green pen light and looked all under the hood.
I see those sniffers online at Amazon starting at 20.00 and up. Maybe worth the investment.

 

[Uncle Gump]

Refrigerant also carries oil throughout the system... most times you can see that oil leak at the point of failure. Not wet necessarily... but a tacky dirty looking area. Not sure I would trust a $20 leak detector.... Maybe they have gotten cheaper....

 

[adsm08]

With the system charged drip some water into the service valve. They won't easily show a leak under most circumstances, but will blow bubbles in the water if leaking.

Evaporator leaks are hard to find, but uncommon to have. They can usually by pinpointed by dye coming out of the drain.

Also look for gummy residue on the AC lines around rubber to metal crimps, or at the joints. Most leaks will blow some of the oil out and it will collect dirt, which helps to pinpoint the leak.

While most AC guys have a sniffer, they take a fair amount of skill to use well. At my last dealership out of 16 guys and 4 senior masters I was the only one who was really proficient with it. I was also the only one who had bothered to read all the instructions.

 

[engine]

My mechanic, once the caps were off, and using a UV light, noticed the Schraeder valve (just like the ones in our tires) in the tube next to the battery was bubbling. For a few cents plus the cost of the refrigerant, all is well again. We had previously put some dyed refrigerant in to help spot the leak.