Massey Ferguson AC22 – AIRCON: Optional Cab Heater Pump Relay Signal From AC Module (AIRCON)

Heater accelerator pump / Water pump relay output error. The system logs this code when the Air Conditioning control module detects that the relay controlling the cab heater's water accelerator pump is not operating correctly.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• 8670
• 8690
• 8450
• 8460
• 8470
• 8480
• 4700 Series
• 5600 Series
• 5700SL Series
• 7700 Series

1. 1

   Locate the heater accelerator pump relay (designated as X453 in electrical schematics)

2. 2

   Test the X453 relay by swapping it with a known good relay of the same amperage

3. 3

   Inspect the wiring harness between the Air Conditioning control module and the X453 relay for open circuits, shorts to ground, or loose/corroded connectors

4. 4

   Supply direct 12V power to the heater accelerator pump to verify if the pump motor itself has failed or seized

1. 1

   Turn off the tractor and disconnect the battery to prevent electrical shorts.

2. 2

   Access the cab fuse/relay panel and locate relay X453.

   Location varies by model, often on the right-hand pillar or under the console.

3. 3

   Remove the relay and inspect the terminal pins for burning or corrosion.

4. 4

   If the relay is faulty, replace it with a new OEM relay.

5. 5

   If the relay is functional, trace the harness to the heater accelerator pump (water pump).

   Inspect the pump's electrical connector.

6. 6

   If the pump is receiving voltage but not running, drain the coolant lines leading to the cab heater core, remove the defective accelerator pump, and install a replacement pump.

7. 7

   Refill and bleed the engine coolant system.

8. 8

   Reconnect the battery, start the tractor, and turn on the cab heater to verify operation and clear the AC22 fault code.