AC System From Scratch - 1989 325i

[SethB]

The first image (3 pin connector with two pins jumped) is the compressor clutch, usually one wire running from behind the clutch on the compressor, and obviously plugs into the pin that's not jumped.

2nd pic is the radiator temp sensor as RogueToaster mentioned.

The 3rd connector is the high or low pressure switch (I forget which) that goes onto the dryer. There is no temp sensor on the dryer. Originally there were two pressure switches, one for high pressure, and one for low pressure. The newer dryers for converting to R134a have a combined high/low switch. So either there's another connector floating around in that area (look up front underneath the headlights), or it's already been jumped. Check out the Google Docs link at the bottom of the first page here to get the official BMW tech bulletin for the conversion:

https://www.r3vlimited.com/board/forum/e30-technical-forums/general-technical/313178-converting-to-r134a-read-this-before-doing-it?t=342398

Good luck!

[gilber33]

I found this picture on ebay of a dryer and it looks like the round connector with the two female ends would fit this. Is that the pressure switch? And then the other sensor is the evap temp sensor? I did not find another connector in there that would fit that other sensor. Maybe it got tucked under the fender or something.





So the more reading I do I see there used to be a high and low pressure switch that was updated to a single pressure switch. To have the updated system, do I need something like this which would involve eliminating the round, two-prong connector and replacing it with the female connector included in the kit pictured below:



And also found this thread which shows what I assume the dryer in my e30 looked like and the newer style one that went from the two switches to one. A couple posts later it says you take either connector from the original setup and splice in the connector for the new pressure switch and the remaining connector gets a jumper wire. My only problem is I didn't see the other pressure switch connector - just the one. Hopefully it's tucked down into the fender or something.

[gilber33]

The three wire is for a temp sensor in the rad, where that brass plug is, and the three prong with the looped connection might be for the old style pressure switch with 134A conversion, or for the compressor depending on the compressor spec'd for the car from new. Either way, the compressors available today will probably be one wire, and are often a flat single connector.

I looked up used compressors for this car and they had the connector that the one with the looped wire would fit in to. I need to figure out what that third connector is for though. That one I assume is for the evap temp sensor on the dryer but I’m not sure and couldn’t find an example of one that this would plug into. Sent from my iPhone using Tapatalk

[roguetoaster]

The three wire is for a temp sensor in the rad, where that brass plug is, and the three prong with the looped connection might be for the old style pressure switch with 134A conversion, or for the compressor depending on the compressor spec'd for the car from new. Either way, the compressors available today will probably be one wire, and are often a flat single connector.

[gilber33]

So the E30 I picked up a while ago has the ac system entirely removed froward of the firewall. RealOEM helps me get an idea of what lines/hoses IÂ’ll need and some pictures I have found give me an idea of the dryer install and location. But it now I am having a hard time understanding the evaporator temp sensor thatÂ’s on the dryer. I think I found the compressor connector: The aux fan switch on the radiator connector: That just leaves this one: Is this for the evap temp sensor on top of the dryer? And if so, how do I know which temp sensor my car is supposed to have? I think I saw there are a couple different styles.