Massey Ferguson 10.00.21 – AIRCON: Air Conditioning Compressor Relay Signal From AC Module Issue

The Air Conditioning control system has detected an abnormal, missing, or out-of-range electrical signal on the circuit responsible for controlling the AC compressor clutch relay. The system is unable to properly engage the compressor or verify the relay's state, resulting in a disabled air conditioning system to prevent electrical damage.

• 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
• 5710SL-5713SL
• 7600 series
• 7700 series
• 8600 series
• 7614-7626
• 7714-7726

1. 1

   Verify the tractor's system voltage, as low voltage can cause relay drop-outs and trigger false signal codes.

2. 2

   Locate the AC compressor relay in the fuse/relay panel and inspect the pins for corrosion, burning, or melting.

3. 3

   Swap the AC compressor relay with a known good relay of the exact same type to see if the fault clears.

4. 4

   Check the wiring harness between the AIRCON module and the relay block for continuity, shorts to ground, or broken wires.

5. 5

   Check the resistance of the AC compressor clutch coil at the compressor, as a shorted coil can draw excessive amperage and damage the relay.

1. 1

   Power Down

   Turn off the tractor ignition and disconnect the negative battery cable to prevent electrical shorts during repair.

2. 2

   Access the Relay Panel

   Open the main fuse and relay box (location varies by cab model, typically found on the right-hand console or B-pillar).

3. 3

   Remove the Faulty Relay

   Extract the AC compressor relay.

4. 4

   Inspect the Socket

   Look closely at the female terminals inside the relay socket. If the terminals are spread apart or show heat damage, the socket pins must be re-pinned. If they are clean and tight, proceed to the next step.

5. 5

   Install the Replacement

   Plug the new OEM AC compressor relay into the socket, ensuring it seats firmly.

6. 6

   Restore Power

   Reconnect the negative battery cable.

7. 7

   Test Operation

   Start the tractor and turn the AC to the maximum cooling setting. Verify that the compressor clutch engages and the cab begins to cool.

8. 8

   Clear Codes

   Use the AGCO Electronic Diagnostic Tool (EDT) or the tractor's dashboard diagnostic menu to clear the 10.00.21 inactive fault code from the AIRCON module's memory.