Izzrock

Need help with heat. Air blower motor works fine....but no hot air comes out only luke warm air (more cold than warm) when the temperature is set to hot. Is it possible for the thermostat or heater core malfunctioning or something else???

mtcookson

iTrader: (2)

sometimes junk will get stuck in the heater core. what you can do is have the heater core flushed. what i did was take a garden hose and run it through the heater core forwards and backwards to be sure to get any junk in there out. worked well and i have very good heat now.

there are two plugs on the fire wall for anti-freeze to go into. the top is the inlet to the heater core and the bottom is the outlet. take both hoses off and stick a garden hose to each and run water through them. be sure the engine has not been ran. cold water on hot cast iron manifolds doesn't equal good things.

there are a number of other possibilies too. does your temp gauge read normal (about pointing horizontal)? could be a stuck thermostat and if it is, your temp gauge would be reading very low.

you could also have low coolant. check your coolant level.

make sure the little lever on the left side of the air control stuff is pointing down when opperating the heater also.

Delvin

To add to what mtcookson just said about the thermostat if it takes a long time for your engine to heat up then it probably stuck open. I replaced mine when i changed my water pump because my heat used to take forever to heat up and then it would cool off when driving too. It used to take about 15 min to get to normal operating temp and after replacing the thermostat it takes about 5 min. Also, if you have buildup in your heater core it also prob means you have clogs elsewhere in your cooling system. Take it to somewhere that does coolant flushes or you can do the entire system yourself with flush kits they sell at parts stores.

MrRogerStatus

iTrader: (4)

Very interesting , cause i'm having the same problem. Last year i remember i had to start the car with the heater on full blast for about 10-15 mins. before i was ready to leave to go anywhere( made me wish i had remote start.)

MaximamixaM

Make sure your coolant in the radiator is at the right level, as well as in the other tank on the fender. My Maxima had a winter of poor heat. Some heat on the drivers side, cold air on the passenger. Eventually it even started to run hot-the motor that is. So I turned of the engine. Let it cool. Found out it was low on coolant. Topped off the coolant and heat, lots of heat out of all vents! Interestingly it only began to run warm that one time, it had normal engine temps for a long time, even though it was low on coolant, and I was freezing in the interior.

rcy

Hlere's a TSB related to poor heater peformance if you've recently changed or are about to change your coolant.

APPLIED VEHICLE(S): 1989 & 1990 Maxima (J30)
SERVICE INFORMATION


Some 1989 and 1990 Maxima vehicles may exhibit poor heater performance. A customer
may complain that, "the heater takes too long to produce any heat...once the heater starts
working, it provides adequate heat." This incident occurs because air bubbles have
become trapped in the heater core. A new cooling system bleeding procedure, which
differs from the earlier published procedure (EM89-009/TS89-161), has been developed to
resolve this complaint.
Nissan recommends engine coolant change every two (2) years or 30,000 miles under
normal use. This procedure should be used whenever coolant is changed.
SERVICE PROCEDURE
1. Lift only the front end of the vehicle, so that the bottom edge of the front bumper fascia
is about 990mm (39") above the ground. Make sure that the exhaust finisher is not
damaged by contact with the ground.
[Raising the front end of the vehicle lowers the heater core location below the radiator
inlet opening.]
NOTE: If starting with an empty heater system (no coolant), the system should be filled
with coolant with the front end already raised.
2. Make sure the engine is cool. Remove the radiator cap and add coolant as required so
that the coolant level comes up to the radiator filler opening.
3. Turn the engine ON and run it at idle.
4. Move the temperature control lever to the "full hot" position on vehicles equipped with a
manually controlled air conditioning system or 85° Fahrenheit for an automatically
controlled air conditioning system.
5. Select "Foot" mode for vehicles equipped with manually controlled air conditioning
systems. Make sure the air conditioner is OFF. Select "FOOT & ECON" mode for
vehicles equipped with an automatically controlled air conditioning system.
[If the A/C compressor is left ON, the engine fan runs continuously. This keeps the
engine temperature low and does not allow the thermostat to open. Also, if the A/C
compressor is left OFF, the engine fan will come ON when the thermostat opens.]
6. Increase the engine speed to about 1500 RPM and hold. Decrease the engine speed if
there is excess coolant spillage from the radiator inlet opening. Place a small object
(e.g. a folded piece of paper) between the throttle drum stopper and the intake manifold
to hold the engine speed.
7. Watch for air bubbles coming out of the radiator inlet opening to make sure the air
bubbles are being purged. Add coolant as necessary to maintain a full radiator. The
coolant level, as seen at the radiator inlet opening, will drop when the thermostat opens.
Do not add coolant when the thermostat is opened as the radiator will overflow when
the thermostat closes. When the engine fan is running it is a good indication that the
thermostat is in the "open" position. This procedure must be run for at least 30 minutes
or until large air bubbles (larger than 5mm diameter) stop coming out to ensure that all
air bubbles are purged from the cooling system. This usually requires the thermostat to
open on two separate occasions. Increase the engine speed to about 1500 RPM and
hold. Decrease the engine speed if there is excess coolant spillage from the radiator
inlet opening. Place a small object (e.g. a folded piece of paper) between the throttle
drum stopper and the intake manifold to hold the engine speed.
8. After 30 minutes, there still may be tiny bubbles (less than 5mm diameter) coming from
the radiator filler opening. It is normal for bubbles of this size to continue, so it is not
necessary to continue the procedure until the small bubbles stop.
9. After the bleeding procedure is complete, remove the small object inserted between the
throttle drum stopper and the intake manifold and return the engine to idle. Add coolant
to fill the radiator and immediately place the cap back on the radiator.
10.Slowly lower the front of the vehicle to the ground.
11.Add coolant to the reservoir tank until the level reaches the "MAX" mark. Remove the
screw which secures the coolant reservoir tank, and with the return tube attached, lift
the reservoir tank above the radiator. Tilt the reservoir tank so the return tube is at the
lowest point. Squeeze the return tube to purge the air trapped in the tube. When the
return tube is filled with coolant, return the reservoir tank to its proper location.
12.Shut the engine OFF. The engine should be allowed to cool down. If the system is not
completely filled, some coolant will be sucked back into the engine. Additionally, the
procedure should be repeated at least once to ensure that all of the air has been bled out of the system.