Jim Grant's Tech Tips
'94 Nissan Sentra, 10 minute A/C
just had the condenser replaced in my '94 Nissan Sentra. The car cools
fine for about 10 minutes, then commences to blow warm air. After turning
off the A/C switch for about 30 seconds and then back on, the car cools
fine for another 10 minutes or so. The local tech says it is a bad thermal
expansion valve. I am not sure to believe him, and don't want to waste
any money. Is the thermal expansion valve a possible cause? Or should
I be looking somewhere else for the problem?
the expansion valve could be the cause. But, there could be an internal
moisture problem as well. The expansion valve controls the flow of refrigerant
through the evaporator. The evaporator is the part of the A/C system that
provides/makes the cold air. If the expansion valve sticks in the closed
position it will not let enough refrigerant through which equals no cooling.
This valve can also stick in the open position which floods the evaporator
and little to no cooling occurs. Then there's that moisture thing. Moisture
inside the A/C system will cause ice to form. Guess where that ice forms?
At the expansion valve. The only way to remove the moisture is to apply
a vacuum to the system for hours in temps preferably above 70 degrees
and to replace the receiver drier. The receiver drier has an absorbent
in it to remove moisture. Yes your tech could be right and he could be
wrong. That's the fun part of cars.