Evaporator Pressure Testing

[waynegarbo]

Can the evaporator be pressure tested with a hand vacuum pump if one can Jerry rig it at its firewall opening on one side and plug off the other port side? Especially if one was to flush it out first.

[beav700]

Sure, why not. I assume you want to find a leak and make sure its the evap before tearing down the dash. The green dye finds leaks easily in the front but not in the dash.

[waynegarbo]

I have read the way you know if an evaporator is leaking is with one of those sniffer's placed in the vent. But I'd rather not do a full AC repair, replacement, and recharge only to find out the sniffer fails the evaporator. And I don't have a sniffer anyway. If my evaporator is leaking I'm not up for the removal. It sounds like a nightmare.

[jimmy57]

Dye will show in drain in most cases but vac testing is fine too. The sniffers are iffy. The tip gets conductive between and anode and cathode and makes it sound off. The problem is the tip is sensitive to other gases and also will sound off if humidity is too high. The refrigerant is heavier than air so you probe the drain with sniffer but the drain can't have water in it and that can be an issue hard to resolve.

[waynegarbo]

Is the drain easily accessible?

[waynegarbo]

I was wondering, is the drain a closed port, to where it will allow for the vac test? I really don't understand the anatomy inside the evaporator.

[beav700]

The drain is just for the moisture to drain out as the evap gets cold and removes humidity (condensation on cold metal) , there is nothing to test there, its just a tube to throw water out of the car. I used sniffers before from Amazon and they were never reliable. Going off for no reason. If you dye the system and don't see it anywhere under the hood and front condenser, it's the evaporator or hoses going to it in the dash.

[waynegarbo]

Do you know the tread size on the evaporator ports?

[jimmy57]

You wouldn't vac test at drain. I was talking about the refrigerant being heavier than air and it often can be detected at drain but drain needs to be dry so the sniffer tester doesn't go off from high moisture. I do not know the sizes of the fittings. Vac testing can b done with those blocked with conical rubber stoppers.

[waynegarbo]

Jimmy please guide me where the drain is and thank you for your answers.