I need to test the electrical connections to my AC compressor.

The description in the Bentley manual seems quite daunting: discharging the AC system, removing the condenser from the car, removing the radiator from the car, sliding the sub frame forward, etc.

Do I need to do all these things to get to the electrical connections? Hopefully I can get by without discharging the AC system.

Are these procedures as daunting as they sound?

Oh, it's a March, 2002 Cooper.

Maybe someone with a lot of experience with the AC system can answer me another question: My dealer said it was an electrical problem, and that they had gotten my AC system blowing cold air when they hooked up another car's electronics to it ( I can't really figure out how they did that, but ... ).
But even when I remove the relay that switches on the compressor, and I complete the circuit (with a wire) that would give power to the compressor (i.e. I am giving +12v to the compressor), the compressor doesn't engage. I have checked all these things with a voltmeter, and the wire is getting 12v.

According to the electrical diagrams there are no more relays or controllers between where I am putting +12v towards it, nor between the compressor and it's ground. Which makes me think that the problem is in the compressor's clutch or the electrical connections to it.

My dealer said the problem was that the DME wouldn't let the compressor turn on because the PS fan and an auxiliary cooling fan were bad. I've replaced the PS fan, and I've realized by auxiliary cooling fan that he meant the stage 1 part of the main cooling fan, and I haven't fixed that and don't really plan to. But if this were true, given that he told me the AC was mechanically working, I think the compressor should engage when I close the circuit that it's controlling relay would close. Right?

Here's another thing: there is no continuity at all between the wire that goes directly to the compressor, that gives it +12v, and ground. Is that expected? It seems to me there should be some finite resistance between those 2 points.

It could be that they unplugged the compressor and failed to replug it - they did remove the stage 1 cooling fan relay and failed to replace it.

They did no real work to the car - they quoted me ever increasing $$ numbers and then seemed like they didn't want to fix it anyway, almost like they couldn't really figure out what was wrong.

Any knowledgeable input would be appreciated.

 

I recently removed my A/C, the compressor is not that difficult to remove. There's not a lot of room down there, but it's do-able.

Go over everything your dealer said they touched just to make sure that everything is how it should be.

I would try the least expensive thing first...the pressure switch. To do that you need to evac the system first, then replace the switch.

 

To get to the compressor, you don't have to remove the condensor or drain the anti-freeze/remove the radiator. But to remove the compressor, you do have to have the system discharged. Everything else the Bentley manual says applies.

 

Right.

BTW, if you happen to need a compressor, I have one for sale.

 

Do you know if the pressure switch is connected to the compressor itself?
What I mean is: is the logic to not let the compressor engage self contained in the compressor itself, as opposed to going through the car's DME brain?

I was thinking that the DME would get the information from the pressure switch, and then the DME would not let the compressor run by not energizing the relay that engages the compressor's clutch. And I have by-passed that relay and have connected the compressor up to +12v directly.

Now I have to find M8 x 100mm bolts locally in order to slide the MFE forward. I think that will be a challenge.

 

I was able to find the bolts at Home Depot or Lowes, I forget which...maybe it was Ace hardware, they have the largest metric selection.

 

The pressure switch is not directly connected to the compressor. The compressor only has a one wire connector.

The logic for the clutch to cycle is in the DME, and not in the compressor.

You are correct, the pressure switch sees pressure/no pressure and sends the appropriate signal/voltage to the DME for when you hit the little snowflake button. No pressure=No compressor clutch cycling=No A/C

What I have learned with this particular system on the MINI, is that jumping and bypassing doesn't work like we would think it should.

 

i too am in the same dilemma

dealer diagnosed and said the compressor is bad 1400.00 to replace ouch

i am not too worried about doing this job would just like to know how to go about it. if anyone has a write-up

and parts man how much for your compressor

and what other parts do i need to do this job

can i just refill with r-134

 

This thread here has some information about changing the compressor. If you want more details, pm me about it.
Posts number 20 and 22 specifically.
https://www.northamericanmotoring.co...d.php?t=144684

 

i have the ssame problem

dealer diagnosed and said compressor is bad 1400.00 to fix