a/c compressor does not start

[wade623]

What would cause the a/c compressor clutch to not turn on? I haven't gotten around to start checing stuff so I figured I would see if anyone would have an idea where to start so I don't have to waste time checking unnecessary stuff.

[sverker]

The most common reason is too little pressure in the AC system due to leaks

[brcidd]

65% of mobile a/c failure is due to loss of refrigerant due to a leak as mentioned above--- what yr Venture? 2001 and 2002 are famous for condenser leaks-- all OEM will fail at some time or another.....

[wade623]

It's a 2002.
So the compressor clutch will not work if there is no Freon in it? I have never heard of that before, is it some sort of safety thing so it doesn't get damaged?

[sverker]

Yes, there is a switch that checks that pressure is within the required limits otherwise the clutch will not be activated

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[wade623]

Ok. I never heard of that before. So how are you supposed to put more in it if it doesn't run?

[brcidd]

You are missing the point--if your tire was completely flat would you just add air? and let it leak out? you need to fix the leak first-- if condenser is black in front, it is the OEM unit, and most likely has a big oily residue stain on passenger side lower corner- you can see it from 6 ft away, by just popping the hood.

You don't add freon to 134a systems, you add Suva, which is the brand name for 134a Freon is the brand name for R-12 which was done being used OEM in 1994.

The compressor shut off by means of pressure tranducer reading of less than 47 psi in the system, which equates to about only 5% of system charge.

Refrigerant can easily be added to a dead flat system, by pulliung adequate vacuum, and then introducing the gas to the low and or high side with engine not running. Once system sees 5% of needed refrigerant charge, the compressor will kick on automatically, and draw in the rest as a gas through the low side port only.....

[wade623]

I've had tires that sat and were flat and needed air and held it after I filled them but that is kind of besides the point. Also Freon was more of a general term.
I looked at the condenser and it is black but didn't really have an oil stain on it so I might have to take a closer look at it when I get a chance and look at it more because I don't really need to do anything with it at the moment I was just looking for some info about it for when I do it.

[wade623]

What do you need for a vacuum? Is there something special that you have to use?

[brcidd]

A vacuum pump comes to mind-- rent one, borrow one from autozone if needed- but you must have all the air out of the system prior to charging-- you can "borrow" a gage set from autozone as well...

[Tech II]

Wade, from your answers, it seems you don't know anything about A/C work....if you do wish to try to tackle this, I suggest you get an A/C manual for your vehicle and read up on finding a leak, recovering the refrigerant, procedures for fixing the leak, pulling a vacuum, adding the correct amount of PAG oil, and adding the correct amount of refrigerant, by weight....also wear gloves and protective eyewear...

I think someone posted before, that 2002 vehicles supposedly used a different condenser, and did not have the same leak as previous years......but that leak was located on the lower corner, passenger side, at a weld......

Other common places are the shell of the compressor, front seal of compressor, and either hi or lo service valves....

[brcidd]

2001 and 2002 U-vans - Venture, Montanna, silhouette, and their brothers, the Aztek, and Rendevous- all had the same Mitsubishi system with faulty condensers at lower passenger side bracket attachment-- Have analyzed hundreds of these-some have the bracket torn completely loose- and a gaping hole in side of condenser. Never seen one in 2003 models or above-- replacement condensers are aluminum colored (not black as were OEM units) so that is your first hint as to whether or not your condneser has been changed. Replacement condensers do NOT use that bracket- there is no mount at that position- blank place where mounting hole would go.....