Massey Ferguson 22 – AC Module (AIRCON): Optional Cab Heater Pump Relay Signal From AC Module (AIRCON)

Communication or electrical fault on the signal circuit between the Air Conditioning (AC) control module and the relay that commands the optional cab heater water pump. The AC module is detecting an abnormal voltage or lack of continuity on this signal wire.

• 7724S
• Interim Tier 4 (2012-2015)
• 7722S
• 7722
• 7615
• 7720S
• 7716
• 7718
• 7726
• 7715
• 7616
• 7618
• 7619
• 7626
• 7624
• 7726S
• 7614
• 7718S
• 7620
• 7719
• 7714
• 7716S
• 7622
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 5710SL
• 5711SL
• 5712SL
• 5713SL

1. 1

   Relay Inspection: Locate the Optional Cab Heater Pump Relay in the cab fuse/relay panel. Swap it with a known good relay of the same type (e.g., a work light relay) to see if the code clears.

2. 2

   Wiring Continuity: Disconnect the AC Module and the heater pump relay. Use a multimeter to check the continuity of the signal wire between the AC module harness connector and the relay block.

3. 3

   Short Circuit Check: Test the signal wire for a short to ground or a short to power.

4. 4

   Connector Inspection: Inspect the pins on the back of the AC Module / Climate Control Panel. Look for pushed-out pins, corrosion, or signs of moisture intrusion.

5. 5

   Pump Load Test: Verify that the cab heater pump itself is not shorted internally, as an excessive current draw can sometimes damage the relay or the module's driver circuit.

1. 1

   Disconnect Power

   Always disconnect the negative battery cable before working on the tractor's CAN BUS or AC module circuits.

2. 2

   Access the Components

   Remove the necessary interior cab trim to access the AC Module (Climate Control Panel) and the main cab relay board.

3. 3

   Replace the Relay

   If the relay failed the diagnostic swap test, install a new OEM relay into the board.

4. 4

   Repair Wiring

   If a break or short was found in the harness, splice and heat-shrink the damaged section of the signal wire.

5. 5

   Module Repair/Replacement

   If the wiring and relay are perfectly intact, the internal driver inside the AC Module has likely failed. The Climate Control Panel will need to be removed and either replaced with a new OEM unit or sent to an agricultural electronics remanufacturer.

6. 6

   Reassembly and Testing

   Reconnect the battery, turn the key to the ON position, and clear the inactive fault codes. Turn on the cab heater to verify the pump engages and no new codes are thrown.