Poor Heat - 95 LeSabre

[CarDude225]

In May 07 I replaced the stock 195deg thermostat with a 180deg thermostat & flushed cooling system.

In Dec 07 I took a trip north into frigit conditions and noticed that the heat in this car is not super strong but it is sufficient.

In Jun 09 I replaced a leaky waterpump.

In winter of 09 to present I have received complaints from the driver that the heat "doesn't work".

Today I checked the heat and it seems to blow very mildly warm after the car warms up - far from true "heat". So I confirmed that the temperature lever on the control panel is causing the temperature to change (blend door?). Then thinking the heatercore may need to be bled (due to previous coolant flush) I pulled the outlet hose off of it with engine running and allowed any air to come out. I noticed such a slow rate of discharge of coolant at idle. So thinking there was a restriction in the core I put the outlet hose back on and took the inlet hose off and noticed the same slow flowrate.

I assumed that the lower temperature thermostat was opening too soon causing this low flowrate or perhaps it was stuck open. It was not stuck open. I replaced the thermostat with a 195 deg Stant (new). After changing the thermostat I did not check to see if the heater core flowrate increased or not.

Conclusion: Changing the tstat seems to have helped increase heat output just a little, but not significantly.

When engine is reved for a few minutes I am getting warmer heat but not hot - about 100 deg as measured by thermometer. The ambient temperature around here today is about 65deg.

Question: Why would there be such a low flowrate of coolant going to the heater core?

[maxwedge]

Air in the system, resticted heater core are the most common reasons, assuming the controls are working properly.

[imidazol97]

Originally Posted by CarDude225

In May 07 I replaced the stock 195deg thermostat with a 180deg thermostat & flushed cooling system.

In Dec 07 I took a trip north into frigit conditions and noticed that the heat in this car is not super strong but it is sufficient.

In Jun 09 I replaced a leaky waterpump.

In winter of 09 to present I have received complaints from the driver that the heat "doesn't work".

Today I checked the heat and it seems to blow very mildly warm after the car warms up - far from true "heat". So I confirmed that the temperature lever on the control panel is causing the temperature to change (blend door?). Then thinking the heatercore may need to be bled (due to previous coolant flush) I pulled the outlet hose off of it with engine running and allowed any air to come out. I noticed such a slow rate of discharge of coolant at idle. So thinking there was a restriction in the core I put the outlet hose back on and took the inlet hose off and noticed the same slow flowrate.

I assumed that the lower temperature thermostat was opening too soon causing this low flowrate or perhaps it was stuck open. It was not stuck open. I replaced the thermostat with a 195 deg Stant (new). After changing the thermostat I did not check to see if the heater core flowrate increased or not.

Conclusion: Changing the tstat seems to have helped increase heat output just a little, but not significantly.

When engine is reved for a few minutes I am getting warmer heat but not hot - about 100 deg as measured by thermometer. The ambient temperature around here today is about 65deg.

Question: Why would there be such a low flowrate of coolant going to the heater core?

Where to begin. Since you took off the top hose on the heater, it should have gotten the air out when it was off, if there was an any in the heater. As to the flow rate, the real test would have been to have someone increase the throttle to 1500 or 2000 while you had that hose off and see if a far faster flow came through.

First make sure the radiator is filled to the top. When you open the cap after the car has cooled a while, the radiator should be full. Then to help move air out of the heater core, run the engine at 2500 for 10 seconds. But do this after the car is fully warmed up to where the lower hose is warm on the radiator. Repeat that 4 times. I position my car with the heater core on the downhill direction on the driveway to help any air get out of it.

After you're sure there is no air in the heater, and the car is warm, run the AC blower on high and see if the outlet hose on the heater is almost as warm as the inlet hose. If the flow is adequate, the water should be going through faster enough it doesn't get cooled down substantially by the air blowing over the heater core. I believe the motor is to be above idle for this. I'd try it at about 1500.

If you get a reduced flow indicated by a cool outlet hose, your only hope is chemical flush to try to clear the radiator core.

If the hose is staying fairly warm, take off the cover under the dash and see what the positioning is for the electric actuator on top of the heater box. It may be slipping and not moving the temperature blend door all the way to the extreme where the air all goes over the heater core, and therefore you're getting air that's blended with cold air.

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