Massey Ferguson 10.03.19 – AC Module: Issue With The Heater Valve (AIRCON)

A malfunction in the heater control valve circuit or its mechanical operation. The system has detected that the valve—which regulates the flow of hot engine coolant into the cab's heater core—is either blocked, experiencing a stepper motor/actuator output error, or suffering from an electrical fault (such as an open circuit or short).

• 7724S
• 5712SL
• 7722
• 7722S
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7726S
• 5711SL
• 7718S
• 7719
• 7714
• 7716S
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724
• 4700 Series
• 4707
• 4708
• 4709
• 4710
• 5600 Series
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 5700 Series
• 6700 Series
• 6700S
• Global Series
• 7600 Series
• 7614
• 7626
• 7700 Series
• 8600 Series
• 8700 Series
• 8732
• 8737
• 8740
• 8S Series
• 9S Series
• 1085
• 1105
• 1135
• 1155

1. 1

   Inspect Hose Routing: Verify that the heater hoses have not been installed in reverse order during a previous service. If hoses are reversed, the heater valve outlet side is exposed to high pressure, which can force the valve open or permanently damage it.

2. 2

   Electrical Testing: Use a multimeter to check the wiring harness and connector leading to the heater valve actuator. Look for shorts, broken wires, or high resistance. Verify that the AC module is sending the correct voltage signal to the valve when the cab temperature is adjusted.

3. 3

   Mechanical/Cable Check: If the tractor utilizes a cable-operated valve (common on older or specific trim models), check the cable adjustment to ensure the valve is fully closing and opening without binding.

4. 4

   Physical Blockage: Check if the valve is physically seized or blocked open by debris in the coolant system.

1. 1

   Cool Down

   Turn off the tractor and allow the engine and coolant to cool completely to prevent severe burns.

2. 2

   Locate the Valve

   Locate the heater control valve, which is typically installed inline with the heater hoses routing from the engine block to the cab firewall.

3. 3

   Clamp Hoses

   Use hose pinch-off pliers to clamp the heater hoses on both the inlet and outlet sides of the valve. This prevents excessive coolant loss and air from entering the wider cooling system.

4. 4

   Disconnect

   Unplug the electrical connector from the heater valve actuator (or disconnect the control cable if applicable).

5. 5

   Remove the Valve

   Loosen the hose clamps securing the hoses to the valve. Carefully twist and pull the hoses off the valve fittings. Remove the faulty valve.

6. 6

   Install the New Valve

   Position the new OEM heater valve, paying strict attention to the flow direction arrows (do not reverse the inlet and outlet).

7. 7

   Reassemble

   Push the heater hoses onto the new valve fittings and secure them tightly with the hose clamps. Reconnect the electrical connector or control cable.

8. 8

   Test and Bleed

   Remove the hose pinch-off pliers. Start the tractor and turn the cab heater to maximum to allow coolant to flow through the core. Check for leaks at the hose connections.

9. 9

   Top Up Coolant

   Check the engine coolant reservoir and top up with the correct Massey Ferguson Extended Life Coolant as needed. Clear the fault code from the AC module.