Arkansas HVACR NewsMagazine September 2023

HVACR NewsMagazine September 2023

Tech News

Leak Location #2: Indoor Evaporator Coil

• A brass cap with an O-ring: If there is no O-ring, it will not seal. • A flared cap: This type of cap needs to have a drop of refrigerant oil on the inside of the flare to seal. • A locking cap: This type of cap should have an O-ring inside to seal.

A leak may develop at the indoor evaporator coil where the tubing goes through the galvanized tin. This is due to rust forming where the two dissimilar metals meet. Move an ultrasonic leak detector along the entire evaporator coil to find the leak location (see the following two photos below) . Noise is heard and the LED display light rises higher on the ultrasonic leak detector as the tip of the tool gets closer to the leak location.

In order to test the valve core, use a brass end cap with a tiny hole drilled in the flat end surface. This is used temporarily to test for a leak, so that bubble leak detector does not get into the valve core area. (If bubble leak detector gets into this area, it needs to be blown out.) Apply non-corrosive bubble leak detector onto the test cap where the hole is. If a bubble forms here, there is a leak in the valve core (see photo below) . (NOTE: A leak at this location is the easiest one to find on the entire air conditioning system. An ultrasonic leak detector is required at all the other possible leak locations.) This valve core may need to be tightened or replaced. Do this by using a valve core removal tool.

To determine exactly where the leak is, apply non-corrosive bubble leak detector to the area on the tubing where the noise was heard. Wait several minutes for a bubble to form, or for foam to appear on the copper tubing. The bubble(s) or foam shows where the leak is.