A/C compressor not turnin on - LotusTalk - The Lotus Cars Community
 
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post #1 of 6 (permalink) Old 07-20-2017, 05:06 PM Thread Starter
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A/C compressor not turnin on

I have a 2005 Lotus Elise and I have been troubleshooting the AC for over a month now. Listed below are the things I have tried.

1. Checked all fuses...both under dash and under access panel.
2. Replaced thermostat with upgrade kit
3. Replaced resistor pack with relocation upgrade kit.
4. Switched out relay pack over passenger wheel well.
5. Checked coolant level and pressure.

Current state:

The blue light on the ac control turns on and the fan runs.

If I apply power directly to the compressor it turns on and blows cold.

If I power the compressor fuse under the dash the AC turns on and blows cold.

Things to note. I bought the car last winter in Wisconsin so I thought the ac was blowing cold but it was also 15 degrees outside so I later found out I was mistaken.
Before I owned it, (in 2012) the car had a BOE REV400 with a DRS x-2 EFI and mil spec harness installed by BOE. The car only has about 1000 miles since the install. The reason I mention the x-2 EFI is it is the only thing left I can think of that would cause the AC compressor not to turn on.

If anybody had any ideas or can help I am literally pulling my hair out.

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post #2 of 6 (permalink) Old 07-21-2017, 04:38 AM
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It sounds like you have covered the bases, I would check continuity between the switch pack and the compressor, and then back through everything.
Is the switch pack seeing the fan on signal?[I think the light means yes]
is the thermostat seeing voltage etc



When you look at the wiring diagram it is not that complicated
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post #3 of 6 (permalink) Old 07-21-2017, 10:14 AM
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I had a similar problem with my 05 Elise, BOE 300 and DRS X-2 EFI. I could get everything to work by jumping relays, by passing switches and powering up various components. But when I had everything hooked up the AC compressor wouldn't turn on. Finally one day I was determined to see if I could find the problems by back tracking from the AC relays and back by temporary. What I finally found was that the EFI AC connector worked when I disconnected it but would not work when I connected it to the EFI. One of the pins would retreat back into the harness when connected. When I disconnected it I would get voltage on one end, could apply power to the other end and the compressor would kick on. But when I connected the connector it pushed the pin back and broke the connection. After all of that I also ended up with a charge leak in the hard line in the sill. I have most of this documented on the forum.

"It always seems to be something!"
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post #4 of 6 (permalink) Old 07-21-2017, 12:49 PM Thread Starter
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Quote:
Originally Posted by lotus72Eur View Post
I had a similar problem with my 05 Elise, BOE 300 and DRS X-2 EFI. I could get everything to work by jumping relays, by passing switches and powering up various components. But when I had everything hooked up the AC compressor wouldn't turn on. Finally one day I was determined to see if I could find the problems by back tracking from the AC relays and back by temporary. What I finally found was that the EFI AC connector worked when I disconnected it but would not work when I connected it to the EFI. One of the pins would retreat back into the harness when connected. When I disconnected it I would get voltage on one end, could apply power to the other end and the compressor would kick on. But when I connected the connector it pushed the pin back and broke the connection. After all of that I also ended up with a charge leak in the hard line in the sill. I have most of this documented on the forum.
So if I understand correctly you are talking about where the ac wire plugs in to the ECU not where the wire connects to the compressor? Do you happen to remember which pin it was?

You got my hopes up for the first time in days!
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post #5 of 6 (permalink) Old 07-22-2017, 07:18 AM
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AC Problems

Paul (?)
I too would have pulled my hair out over my AC but mother nature beat me to it. Anywhoo, I screwed around trying to get the AC to work for over two months off and on.

A little background. While I was looking for a supercharger I ended up getting a complete engine with a BOE 300, X2 EFI and transmission. I decided to just replace the engines out. This was one of the older setup that required that the engine harness and body harness needing to be wired and spliced in. The engine came with the harness spliced and installed and I just(?) had to splice about 12 wires on the body harness. Once I pulled the original engine it was pretty easy to do the splices. I don't know how you would do it with the engine installed. Once I got everything switched out about the only thing wasn't working was the AC. I worked with Kris at DRS for about two months going back and forth by E-mail. We never were able to narrow down the issue.

The EFI system that I received with the engine has a set of extra plugs on the connectors so that the original ECU can be used by just switching out the connectors. For example: the connector for the AC clutch is a female that is wired into the body harness. The EFI has two male AC plugs-one for the EFI and one that is the original ECI. You connect only one depending on the ECU being used. I have only used the X2 ecu as I don't have the original one flashed for the supercharger (I am not sure of this as I got an original ecu with the engine also.).

The picture of the plug that I have attached is the one that I had to wire into the body harness. One is the engine harness pin 53 (Blue/Black) to compressor relay and pin 56 Pink/light blue is the Trinarty(sp?) Switch. I have also attached a couple of worksheets that I used in my trouble shooting with some notations that may or may not apply in your case. Also a spreadsheet of the pins outs.

As best as I can describe my issue is that when I unplugged the AC body connector I would get the 12 volts going to the plug (on pin 53) coming from the ECU with the engine running and the AC turned on. I could then apply 12 volts to the other connector and the AC clutch would kick on. But when I connected the two together the AC clutch would not turn on. It turned out that when I connected the two together, rather than connecting, the female ferrule was getting pushed back into the connector rather than making a connection.

I know this all sounds rather confusing.

Good Luck,

If I can be further assistance just contact me.
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"It always seems to be something!"
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post #6 of 6 (permalink) Old 07-24-2017, 07:43 AM Thread Starter
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Thanks for the writeup. Very helpful. I spent some time this weekend and I think I found the problem. Unless I am mistaken I don't have the expansion on the Harness for the X2 to control the AC compressor. I also have the wiring harness where I can switch back to stock but it seems an harness for the AC was never wired in. Or if it was I can't find it.

I have been planning on sending to BOE for a tune, so that I can switch back to the original ECU, and to do a few other upgrades. I guess I now have motivation to get it done asap.

Again thanks for the help. I am not sure how long it would have taken me to figure out if it wasn't for you writeup and pics.

Paul
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