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Find that leak

by 1986chevyman on Feb 17 2019, 11:15 PM

Elite Tech

When suspecting I have an evaporator core leaking, I add oil/dye and run the car down the road to get the dye circulated good. The I come back to the shop and put some white paper under where the A/C drain is. Then run the car with the A/C on and if the evaporator core is leaking the dye will stand out on the white paper. On some cars with a small leak the customer may have to drive the car for a few weeks and then bring it back to check it in this fashion.

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6 Replies

By fordguru May 02 2019, 10:09 PM

a borescope through the blower resistor is a good way to find an EVAP leak without much disassembly the leak usually collects debris,lint or other material. it would be nice if it had a UV light attachment . My shop has also invested in connectors to attach directly to most OEM Evaporators, we can charge them with refrigerant and watch for a pressure loss with our gauge set attached. We also have a nitrogen tank, and fill them with nitrogen for leak testing ( like many residential HVAC techs do)

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By teraflent May 02 2019, 9:55 PM

U/V dye backed up with a good refrigerant sniffer is the only way to go, vacuum test will only inform you there's a gross leak before you waste refrigerant and never tells you were the leak is at. 30" of vacuum in HG is 1 atmosphere (14.7psi) far below any pressure the system will actually endure.

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By 1962impala Apr 12 2019, 5:47 PM

Wow!! This guy is great!!

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By 1962impala Apr 12 2019, 5:47 PM

Ultraviolet dye is the best way to diagnosis a HVAC leak and do a vacuum test prior to confirm the system has a leak.

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By jspeed222 Mar 15 2019, 10:43 PM

a little water through the cabin filter housing or open air intake will speed this process up and give you an answer right away

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By kevinmuhle Feb 23 2019, 1:53 PM

cornstarch is great for leak detection. it soaks up liquids and since its white it will show the dye under uv light.

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