2005 407 Air Con not engaging

[Zeke]

I have just replaced the Air-Con Compressor with a new one as the old one's seal(s) leaked.
I had the Air-Con re-gassed but the compressor clutch will not engage, I have tried turning the
interior fan on and off that had no effect at the same time reduced the interior setting to 18C, still not working.
Hopefully someone may be able to help me fix the problem.

[GiveMeABreak]

Did you have the compressor professionally fitted by an Auto AC engineeer / dealer? When it was gassed was the appropriate amount of oil added to the system as well as the gas?

It really needs checking by an A/C specialist to make sure there are no blocks in the system. Another issue may be that your heater matrix may be blocked, which could be preventing circulation.

With the engine running, get somebody to switch the A/C control on and off. You should be able to hear the compressor clutch engage and make a clicking noise each time the compressor clutch engages. If it does not, then the conditions may not be right for the compressor to operate and the engine ECU may disable or prevent it from operating to prevent damage.

[mickthemaverick]

Have you checked the shims fitted between the compressor and the clutch? When I replaced my compressor the clutch would not operate and we discovered a change of shim thickness was needed to give the correct clearance!
Here is the link to my thread describing the clutch etc.:
viewtopic.php?p=612544#p612544

[Zeke]

Hi Mick andv Marcyes the compressor was fitted by a profrssional oil and gas was added but the system would not engage. the clutch does not engage when the engine is running and the the A/C control switched on and off. I was able the get the clutch to engage by a direct 12volt from the batter using a spare plug into the yellow connecor on the compressor, but there was no cold air coming from the vents, i also noted that air coming from the vents did not have much velocity!!
Fred

[GiveMeABreak]

Also check fuse F14 in the BSI

[Zeke]

Will check F14 fuse
Fred

[Zeke]

Checked the following fuses ALL OK F14 15 Amp A/C - F21 5 Amp Engine Cooling Fan - F11 40 Amp A/C
Fred

[ozvtr]

Hi Mick andv Marcyes the compressor was fitted by a profrssional oil and gas was added but the system would not engage. the clutch does not engage when the engine is running and the the A/C control switched on and off. I was able the get the clutch to engage by a direct 12volt from the batter using a spare plug into the yellow connecor on the compressor, but there was no cold air coming from the vents, i also noted that air coming from the vents did not have much velocity!!
Fred

IF there is only 1 connector (yellow) on the entire compressor, with the clutch engaged AND the compressor input shaft spinning, the system should get cool. Check that the input shaft is actually spinning when the clutch is engaged. If it's not, the clutch needs to be re-shimmed or the compressor is seized. Otherwise you need to take it back to the person who installed and gassed the system and check the refrigerant pressure ( the amount of refrigerant in the system).

Is there a second connector on the compressor? Typically located on the opposite end to the clutch and pulley. If so there might be a problem with the HVAC ECU, valve or wiring. The second connector is connected to a pressure regulator or refrigerant flow regulator. It regulates the system high and low side pressure differential and increases or decreases the cooling ability of the system without engaging and dis-engaging the compressor clutch. If this valve is not working (for one reason or another) the compressor is effectively bypassed and the system will not cool.

The "professional" should have been able to diagnose the fault. They may not have been able to fix it but they should have been able to find out where the problem was coming from.