98 taurus no heating when engine idles

I just bought a 98 Taurus (3.0L V6 SFI, 12V) and I didn't find there is no heating. After reading some posters here, I know the heat core might be blocked. I had a mechanic flush the heat core. Yellow liquid comes out from the lower hose (green coolant). He only did one direction flush and said that was enough (some posters said one should flush both directions). After heat core flushed, there is still little heat. Then he clamped the by-pass hose, the air is much hotter. He removed the clamp on the by-pass hose, no heat again. He increase the engine speed, hot air comes out. He concludes that the problem is the Ford's design fault: Ford's car are bad at heating (but good at A/C). He also unplugged something near the coolant tank to stop A/C because the A/C is always working (maybe that's why he said the Ford cars' A/C are good).

Now I can only have heating on highway. There is almost no heating when I drive local. What's wrong here? How to get heating in local driving? Thank you very much for your comments.

You might have a large air pocket in your cooling system. Some Fords used a bleeder valve for the cooling system, some have valves integrated into the thermostat. Since you just bought the car, you probably don't know if the thermostat was recently changed. If someone recently changed the thermostat and didn't position it with the valve at the top, that might cause this problem. If your car has a bleeder screw on the cooling system, check for air using the bleeder. Since the heater core was just flushed, there is a good chance you have air in the system.

Does your Taurus have the Electronic Automatic Temperature Control (EATC) system? If so, the A/C compressor may have been engaged because you are using the "Auto" setting. Or, you might have the defroster selected (either EATC or manual controls) which also engages the A/C compressor.

-Rod

The service manual gives the following steps for bleeding the cooling system:
Bleed engine cooling system as follows:

a. Select maximum heater temperature and blower motor speed settings. Position control to discharge air at A/C vents in instrument panel (04320).

b. Start engine and allow to idle. While engine is idling, feel for hot air at A/C vents.

c. CAUTION: If air discharge remains cool and engine coolant temperature gauge does not move, engine coolant level is low in engine and must be filled. Stop engine, allow to cool and fill cooling system as described.

Start engine and allow to idle until normal operating temperature is reached. Hot air should discharge from A/C vents. The engine coolant temperature gauge should maintain a stabilized reading to within the NORMAL range and the upper radiator hose (8260) should feel hot to the touch.

d. Shut engine off and allow to cool.

e. Check engine for coolant leaks.

f. Note: When engine coolant level indicator flashes, approximately 0.946-1.416 liter (1-1.5 qts.) of coolant mixture can be added to the degas bottle after a proper engine coolant system refill.

Check engine coolant level in degas bottle and fill as necessary.

Thank you very much for the advice. I will check to see if my car has a bleeder valve or it is integrated into the thermostat.

My Taurus has no EATC. The manual said A/C will operate at most of climate control modes (except vent and floor heating) if the outside temperature is >10 degree. I didn't know if the garage is warm enough when I repaired my car, but the mechanic said the control parts in the car is broken so that the A/C is always on. Therefore he unplugged something near the coolant tank (is it Coolant Temperature Sensor?) to stop A/C.

If my car uses thermostat and someone didn't position it with the valve at the top, what symptoms will the car have except for no heating? Now, the engine coolant temperature gauge is OK, the needle is blow cool when I just start the engine and stays at the middle after about 5 mins. The engine idle speed is about 1200rpm when I just start engine and it becomes about 750rpm after 2 or more mins. Do I still need to check the thermostat?

Many thanks.


You might have a large air pocket in your cooling system. Some Fords used a bleeder valve for the cooling system, some have valves integrated into the thermostat. Since you just bought the car, you probably don't know if the thermostat was recently changed. If someone recently changed the thermostat and didn't position it with the valve at the top, that might cause this problem. If your car has a bleeder screw on the cooling system, check for air using the bleeder. Since the heater core was just flushed, there is a good chance you have air in the system.

Does your Taurus have the Electronic Automatic Temperature Control (EATC) system? If so, the A/C compressor may have been engaged because you are using the "Auto" setting. Or, you might have the defroster selected (either EATC or manual controls) which also engages the A/C compressor.

-Rod

By the way, my 96 heats like no tomorrow. We bake in that car. So much for the, "Ford heat stinks", idea!

I do change the coolant every 2 years, so mabey thats the key.