Why is there no power to the a/c compressor on my 406?

[TS4]

Hello,
Air condition broke down on my 406 from 2001. The Peugeot shop couldn't find the cause and an air condition specialist shop concluded that it's an electrical error because the compressor doesn't get any voltage. The problem is that the air condition specialist doesn't have a wiring diagram and Peugeot denies to give me one. The one found on http://peugeot.mainspot.net/ is the older 1,8L XU engine. Tried also to exchange a relay in the black box beneth the fuses, which was said to be a common cause but it didn't help. Is there anyone out there that could please help me with a wiring diagram for my 2001 406 sport with 2,2L EW12J4 engine especially covering the air condition system and/or some hints regarding possible cause? Is there for instance a "cut-off relay" and where is it fitted?

Thanks

[Doggy]

Hello & welcome to the forum

I don't have a diagram for the air conditioning, but can tell you that the compressor is controlled by a relay in the built-in systems interface, (BSI). A relay failure is possible, but not common. The compressor will not operate if the low pressure switch, (attached to the condenser), does not detect gas pressure.

By far the most common failure is loss of gas from a leaking condenser.

Are you sure there is gas in your system?

[miniman7]

If all else fails......

http://www.rednecks-unlimited.com/?page_id=24

[TS4]

The air conditionist made a pressure test, so there is gas. He also concluded that there is no power to the compressor, (guess he means the compressor coil?) Peugeot told me about the BSI relay, so I bought a new one and changed the relay although I think there was no fault in the old one. There is a "tick" from the fuse box area when I turn the A/C on.
Someone stated, in another thread, that perhaps the pressure switch needs the compressor to run to be able to change state, a sort of moment 22. Can that be true? How can I force the compressor? Anyone how knows what the compressor coil expects in terms of electricity? voltage? colour of cables?

[Doggy]

Someone stated, in another thread, that perhaps the pressure switch needs the compressor to run to be able to change state, a sort of moment 22. Can that be true? How can I force the compressor? Anyone how knows what the compressor coil expects in terms of electricity? voltage? colour of cables?

That was me...
The compressor has a two-pin connector to operate the clutch. I can't remember the wire numbers or colours. I removed the connector & measured the resistance between the two pins and the compressor casing to determine which pin is the earth. I then re-connected the plug, made a very small nick in the insulation of the other, (+12V), wire, then connected that briefly to the battery +ve via a fused lead. This energised the clutch - I kept it on for maybe 30 seconds to verify some cold air could be detected. I then disconnected the test lead and repaired the insulation.
Mine worked OK after that, (to my surprise) and has continued to work since.

[TS4]

Thank you dogslife!!
I followed your advise, but instead of connecting a wire to the battery I started off with a voltage measurement of the wire and with my 2 years old daughter operating the A/C button I concluded that there actually is power to the compressor clutch. At the same time I could also hear that the engine had to work harder with the compressor engaged and the engine coolant blower increased its speed. Guess there is no need for a battery connection then? And still the car is hot. What can be wrong then?
- No gas? The A/C guy was wrong about the electricity, maybe he didn't fill it up either.
- Faulty compressor? (repair, used or new?)
- Faulty AC/heater air flap motor? (but the pipes from the compressor should be cold, shouldn't they? They're not)
- Any other suggestion?
/TS4

[mjb]

I concluded that there actually is power to the compressor clutch. At the same time I could also hear that the engine had to work harder with the compressor engaged

Easiest way to tell for sure is to LOOK at the compressor pulley and see if the middle section's actually moving when a/c is selected. It should be the lowest pulley in front of the engine (think all engines have the same layout) and should be visible from the wheelarch with the lining removed (loads of effort) or by using a mirror underneath or a telescopic dentist-style mirror from above

What can be wrong then?
- No gas? The A/C guy was wrong about the electricity, maybe he didn't fill it up either.
- Faulty compressor? (repair, used or new?)

Yes and yes. Get someone independent to check the gas pressure, otherwise I suspect it may be time for a new compressor. I'm no a/c expert though

[Doggy]

Strange. You usually only have one problem....

If there's no gas, the compressor shouldn't engage. I guess you could get this behaviour from too little gas, but that's a pure guess.

As mjb says, you've probably got to get someone else to check /recharge it, or take it back to the first place and insist they prove they have filled it with the correct quantity and specification of refrigerant. (750g, R134A, I beleive).