Daikin VRV - Page 80

Method of Troubleshooting Si30-408
76 Troubleshooting
3.2.1 Thermistor
1. Symptoms with Thermistor Resistance Deviation
In Cooling with
Superheat
Degree Control
Code of Thermistors Detecting Various Temperatures
Units using R22, R407C Units using R410A
Tl (indoor liquid pipe temperature) Th2 R2T
Tg (indoor gas pipe temperature) Th3 R3T
• Indoor unit liquid pipe thermistor
· When the resistance deviates to smaller value.
(Higher temperature detected)
Superheat degree (SH) = Tg-Tl
Tg-Tl decreases.
Indoor electronic EV closes.
· When the resistance deviates to larger value.
(Lower temperature detected)
Superheated degree (SH) = Tg-Tl
Tg-Tl increases.
Indoor electronic EV opens.
Superheat operation, cooling
capacity lowering (Freeze-up
protection cannot be detected.)
Wet operation (Freeze-up
protection can be applied
easily.)
• Indoor gas pipe thermistor
·When the resistance deviates to smaller value.
(Higher temperature detected)
Superheated degree (SH) = Tg-Tl
Tg-Tl increases.
Indoor electronic EV opens.
Wet operation
· When the resistance deviates to larger value.
(Lower temperature detected)
Superheat degree (SH) = Tg-Tl
Tg-Tl decreases.
Indoor electronic EV closes.
Superheat operation,
cooling capacity lowering