“….problem with water breaking on top….chemistry hasn't changed…some cars break great…some don't…..sides seem to break great every time.”
Intermittent problems can be troublesome to resolve. Apply cause and effect.
Start with drying agent. What causes it to work? Hydrophobic drying aid creates high surface contact angle on paint surface (glass too) that causes water to bead-up and make car easier to dry.
For drying aid to work effectively, the surface must be clean. “…some cars break great, some don’t…” This implies cars are getting clean.
Is drying aid being applied consistently? “….sides seem to break great every time…” This implies drying aid is being applied consistently, at least on sides.
“DA applied thru mist arch…” Potential problem here could be solenoid controlling top nozzle holders.
What can cause drying agent not to work, excluding proportion, chemistry, etc.?
One potential cause is re-depositing dirt back onto surface prior to rinse.
This can be caused by small hydraulic oil leak that gets on top brush or reclaim system where quality of product water fluctuates because the system is too dirty (filled tanks, clogged filters).
This is more noticeable in winter months when demand can go from zilch to maximum.
Hope this helps.
