Great video (with our old logo).
Sometimes you do not have the capillary tubes size recommended by the manufacturer. The following J/B conversion chart shows how much longer or shorter the replacement cap tube must be.
- Assume 9 feet of .040 cap tube is needed.
- How long would a .036 tube need to be to give the same amount of refrigerant and pressure drop?
- What if all you had was a .042 cap tube?
For a cap tube to work properly:
- It must be sized properly.
- The evaporator load must be at designed conditions.
- The refrigerant charge must be correct.
- There must be a full column of liquid to the cap tube.
Causes of evaporator flooding in a cap tube system:
- Too much high side pressure
- Dirty condenser
- Refrigerant overcharge
- Low evaporator load
- Box temperature too low
- Blocked evaporator (dirt or ice)
- Fan motor bad
- Incorrectly sized cap tube (low pressure drop)
- Inside diameter (I.D.) too large
- Cap tube length too short
Causes of evaporator starving in a cap tube system:
- High side pressure too low.
- Low on refrigerant.
- Low ambient.
- High evaporator load (quickly vaporizing refrigerant)
- Door open or not sealing
- High product load
- Initial start-up
- Hot product in the box
- Incorrectly sized cap tube (high-pressure drop).
- Inside diameter (I.D.) too small
- Cap tube length too long.
Cause for plugged cap tubes:
- Dirt or ice blocking the cap tube
- Filter desiccant can also plug cap tube
- Cut off some cap tube/capillary tubes
- Replace filter drier