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'73 F250 A/C evaporator

Anyone know of a clever, fool-proof way to check an a/c evaporator other than submersing it in water with some air pressure? Pulled the entire heater/ac housing out and am replacing the heater core (not leaking but why take the chance) and want to make sure the A/C evaporator is okay. It looks fine but has a little oil-like residue in one lower area. However, I've been told this is not necessarily an indication of a leaking evaporator. I replaced a lot of the A/C stuff over a year ago, including the expansion valve, compressor, clutch and drier. I changed all the valves over to the R134a and had planned on putting the A/C back into operation but just never got around to it. Since I've pulled the engine and basically overhauled it I think it wise to take care of any heater-a/c problems before they hatch. The valve covers I have are cast aluminum and do not readily permit pulling the heater/ac housing once the engine is installed.

Reply to
The earnest one
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Some years back the compressor on my '81 went bad. After replacing all the replaceable parts in the system, I found that the system would not hold a vacuum. I suspected the evaporator since I discovered an oil residue at the bottom of the piece. I made up a dye solution and filled the evaporator. Sure 'nuff a little while later I saw a red-colored drip.....very small, but it was leaking. Replaced the piece, the system held the same vacuum for 3hrs and all was well again. There may be a better way to check for a leaking piece, but this worked for me.

Hope this helps.......

Dave S(Texas)

Reply to
putt

Maybe mix some dishwashing soap in some water, and spray it all over the lower coil area. If it's leaking, you should see some small bubbles somewhere. If the leak is big enough, often you can hear it. Use a hose, etc to pipe the noise to your ear. Of course, you could use a leak detector to check...But not all detectors are equal...My favorite is my plug in the wall GE type detector. It comes in a blue pseudo leather type case and runs off

117v...It's real sensitive, and can easily spot leaks that small, if it's on the "small" setting. But some of the cheapy hand helds are not so good. With my GE, you could set the probe in the air vent, and let the car sit a few minutes. Then "bump" the fan a second to move the air through the vents. If it's got a leak of any size, that GE will usually start to squeal. It's the most sensitive detector I've ever used, but I haven't tried any of the new high $$$$ multi gas detectors to compare...I've got a battery powered handheld made by GEM, or someone along those lines....Has the little air pump, etc...Piece of junk overall. A fisher price toy compared to the GE... MK
Reply to
Mark Keith

When my '73 was leeking I tried a lot of things but to get a system that will last years without problems I had to take it to the man,(The AC shop that is) where he put 300 p.s.i. Nitrogen in the system and detected a minute leak that I fixed myself.Cost,$40 to the shop,$16 at the self serve yard,and $14 for the r-12 ( I know where to get the little cans).

******************** There are three kinds of lies; lies,damned lies,and statistics.---Disraeli
Reply to
Brian Orion

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