1993 Nissan Sentra Thermostat

Heater problem
1993 Nissan Sentra Automatic 165000 miles

Last winter I replaced the fan in my heater because I had no air blowing at all. Then I had heat for awhile. Now I do not have any heat blowing. When I turn my heat on it blows cold air. Can this be the thermostat? If so where is that located and how do you take it out to check?
Do you
have the same problem?
Friday, October 30th, 2009 AT 3:23 PM

1 Reply

First check coolant level. If OK then remove thermostat and test.

The thermostat is housed in the water outlet casting on the cylinder head on most models. On the GA16DE engines, the thermostat is housed in the water outlet casting attached to the water pump.

Disconnect the negative battery cable.
When cool, open the draincock on the radiator and drain the coolant into a suitable drain pan.
Remove the upper radiator hose from the water outlet side and remove the bolts securing the water outlet to the cylinder head and any other components in the way.
Remove the water outlet and thermostat.

To install:

Clean off the old gasket from the mating surfaces of the thermostat housing and engine block.

When using RTV sealant instead of gaskets, make sure the surface you are working on is very clean before applying the sealant, then apply an even bead. Allow the RTV to dry slightly to form a thin skin. The component MUST be tightened before the RTV dries completely. The bolt torque should be checked again after RTV has completely dried.

When installing the thermostat, be sure to install a new gasket and be sure the air bleed hole in the thermostat is facing upward and that the spring is toward the inside of the engine.
Install the water outlet and tighten the bolts.

GA16DE-13-16 ft. Lbs. (18-22 Nm)

SR20DE-60-72 inch lbs. (6-8 Nm)

If removed, install the exhaust air induction tube clamp bolts.
Install the upper radiator hose, close the draincock and refill the cooling system.
Connect the negative battery cable.
Start the engine and check for leaks.

To test, use string to tie up the thermostat over a pot of boiling water. Dip the thermostat in the water and use a thermometer to inspect at which temperature the thermostat opens.
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Friday, October 30th, 2009 AT 8:22 PM

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