Heater not working?

Partially blocked heater core. This guide can help us tell for sure.

https://www.2carpros.com/articles/car-heater-not-working

Roy

Replace the heater core. it is the problem

This guide can help as well

https://www.2carpros.com/articles/car-heater-not-working

Roy

Check the heater control valve and the air blend door/actuator

Try flushing out the heater core, check the heater control valve and test the engine coolant temperature sensor-if there a problem with the water pump you'll be overheating

If both heater core hoses are getting hot, the blend door is the problem. However, if only one is getting hot, there is a blockage in the core. As far as the blend door, it is located next to the heater core. Not a fun job to get to.

When you flushed the heater core, if the water flowed freely, that isn't the problem. I would focus on blend door. Make sure it is operating fully in both directions. If a mouse or something got in there, it could be blocking it from fully opening. If both heater core hoses are hot, that is where the problem has to be coming from. Plus, if you don't have to, trust me when I say, don't replace the heater core. It isn't a fun job.

Okay, if the heater hoses are hot, the blend door is working properly, and the core is clear. Wow, now you have me stumped. The hoses indicate the coolant is heating the core, the core is clear allowing the coolant to flow and the blend door is opening properly. You should have perfect heat. The only thing I can think of now is the engine isn't getting hot enough, but I think you mentioned it was, correct? This is a basic system and you have done it all and all seems to be working as designed.

Your heater core is leaking coolant. Let me find out whether or not the dash has to be pulled to replace it and i'll get back to ya.

These instructions came from a ford website, I hope this helps. Remember these instructions are for a ranger and aerostar of the same year you have. Good luck

Section 12-03D: Air Conditioning and Heating System, Auxiliary

1997 Aerostar/Ranger Workshop Manual
REMOVAL AND INSTALLATION

Procedure revision date: 05/17/2000
Heater and/or Evaporator Core
SPECIAL SERVICE TOOL(S) REQUIRED Description Tool Number
Heater Hose Disconnect Tool T85T-18539-AH

Auxiliary Heater Core and Seal Assembly

Removal

1.

Remove the first seat behind the driver, if so equipped.

2.

Remove the auxiliary heater and/or air conditioner service cover attaching screws, and remove the cover.

3.

Drain the cooling system following the recommended procedures. Observe all safety precautions. Refer to Section 03-03.

4.

Remove rear seat airflow duct (18C420) by removing one or two attaching screws, as required, and rotating the rear seat airflow duct gently downward.

5.

Remove remaining sixteen screws from cover and remove cover from case.

6.

Disconnect the heater water hoses (18472) at the quick disconnection under the vehicle and plug the disconnects with suitable 5/8-inch plugs.

7.

Slide the heater core (18476) and heater core case seal (18658) out of the housing slot and pull it up through the floor.

8.

Remove the heater water hoses from the heater core (two clamps).

Auxiliary Heater Core Installation

Item Part Number Description
1 19860 A/C Evaporator Core
2 18D283 Auxiliary Heater and A/C Assembly
3 97242-S8 Clamps (2 Req'd)
4 18B425 Heater Core Tube Insulators
5 18658 Heater Core Case Seal
6 18476 Heater Core

Installation

1.

Install the heater water hoses on the heater core (two clamps).

2.

Slide the heater core and heater core case seal into the housing slot, guiding the heater water hoses through the floor.

3.

Connect the quick disconnects under the vehicle.

4.

Fill the cooling system to specification and check for coolant leaks. Refer to Section 03-03.

5.

Install the auxiliary heater and/or air conditioner cover.

6.

Install the rear seat airflow duct.

7.

Install the service cover and passenger seat as outlined.

Auxiliary A/C Evaporator Core

Removal

1.

Remove the first seat behind driver, if so equipped. Refer to Section 01-10.

2.

Remove the auxiliary heater and/or air conditioner service cover attaching screws and remove the cover.

3.

Discharge the refrigerant system following the recommended service procedures. Observe all safety precautions. Refer to Section 12-00.

4.

Remove rear seat airflow duct.

5.

Disconnect the evaporator to compressor suction line (19867) from the A/C evaporator core (19860) and plug.

6.

Using 5/16-inch nut runner, disconnect solenoid bracket from case.

7.

Using backup wrenches, disconnect the evaporator core from the solenoid valve.

8.

Remove auxiliary case cover screws and cover.

9.

Remove connector from heater blower motor switch resistor (18591).

10.

Remove A/C evaporator core.

Installation

1.

Install A/C evaporator core seal (19A672) to tube end of A/C evaporator core.

2.

Install new O-ring lubricated with clean refrigerant oil to inlet line and to condenser to evaporator tube O-ring fitting.

3.

Carefully place A/C evaporator core in case and align inlet tube with solenoid. Tighten connections to 21-27 Nm (15-20 lb-ft) using backup wrench to prevent damage.

4.

Install solenoid bracket to case assembly.

5.

Install new O-ring on underbody suction line and lubricate with clean refrigerant oil. Connect to A/C evaporator core making sure to hear the click of the spring trapping the line.

6.

Wrap evaporator to compressor suction line with insulating tape.

7.

Reconnect connector to heater blower motor switch resistor.

8.

Install case cover.

9.

Install rear seat airflow duct.

10.

Leak test, evacuate, and charge the refrigerant system following the recommended service procedures. Observe all safety precautions. Refer to Section 12-00.

11.

Install service cover and passenger seat as outlined.

Evaporator Core Installation