Massey Ferguson 10.X.22 – AC Module (AIRCON): Optional Cab Heater Pump Relay Signal From AC Module (AIRCON)

Circuit malfunction between the Air Conditioning (AIRCON) control module and the relay that commands the optional cab heater water pump. The AC module is detecting an abnormal signal on this circuit, indicating an open circuit, a short to ground, a short to power in the wiring harness, or a failed relay coil.

• 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
• 5700 series
• 6700 series
• 4707
• 4710
• 6713
• 5600 series
• 7600 series
• 7700 series
• 8600 series
• 8700 series
• 5610
• 7624

1. 1

   Verify the code using the AGCO Electronic Diagnostic Tool (EDT) and check for related AC Module voltage codes (e.g., 10.00.28/29)

2. 2

   Inspect the Optional Cab Heater Pump Relay in the cab fuse/relay box for corrosion, melting, or loose connections, and swap with a known good relay

3. 3

   Perform a wiring harness continuity test between the AC Module output pin and the relay block, checking for open circuits or shorts to ground/power

4. 4

   Check the optional cab heater pump motor for an internal short that could draw excessive current and damage the relay or AC module circuit

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the battery isolator to prevent electrical spikes during repair.

2. 2

   Access the Relay Panel

   Open the main or secondary fuse box (usually located in the right-hand console or B-pillar, depending on the cab model).

3. 3

   Replace the Relay / Repair Wiring

   If the relay failed the diagnostic test, replace it. If the wiring harness showed a break or short during testing, repair the damaged section of the wire or replace the harness segment.

4. 4

   Inspect/Replace the AC Module

   If the relay and wiring are perfectly intact but the AC module is failing to send the ground/power signal to the relay, the internal driver in the AC module has likely failed. Remove the cab control panel and replace the AC Module.

5. 5

   Reassemble and Clear Codes

   Reconnect the battery, turn the ignition on, and use the AGCO EDT to clear the fault codes. Test the cab heater to ensure the pump engages and hot coolant circulates.