A/C Compressor isn't engaging. 30A fuse is good. R2 relay I'm not sure how to check (?).

I understand that with coolant below 8bar the compressor won't kick on. And if I hook up a 134a bottle+gauge I get 0psi when I pull the trigger. And I'm in the red at 100psi if it is just sitting there on the Low port without pulling the trigger. Is this normal? Or is it telling me I have no coolant?

I understand the clutch coil on the R53 go pop easily. But, before jumping into that, What else should I check / What diag. process should I be stepping through?

(This car is new to me, so I don't know if the coolant loss (if there is) was catastrophic or a slow leak).

[Edit: my radiator fan spins in both LOW and HIGH modes; A/C dash light is on solid green]

 

Did you check freon level? If you're low, the compressor will not engage..

 

Well, like I said above.. I just have the 134a bottle+gauge. And when I pull the trigger it reads 0psi, and if it's just sitting there on the Low tap it's in the red at 100psi. So I'm not sure what to make of it, as these things are designed to give a reading when the compressor is engaged. No?

 

When you said, coolant I thought you were referring to engine coolant. Personally, I would take it to someone that does AC work to have the level/pressure checked.

 

Personally, I'm trying to learn more ;p

 

Gotcha, hopefully someone will chime in that knows more. I based my post on a personal experience I had a while back. I had the same problem on a previous car. The compressor wouldn't come on. Turned out to be a sensor that reported the pressure in the system, was a cheap part.

 

I have a gauge manifold on order. That should tell me something useful about the state of the Low pressure side. I'd like to know what pins on R2 to energize to check for operation. And how to check the sensor.

 

Like I said, at least the sensor is cheap -

http://www.waymotorworks.com/a-c-pre...0-r52-r53.html

 

"Start the engine and turn on the A/C, then short out where the relay terminals 30 and 87 plug into the fuse box and see if the clutch starts working."

"If the A/C works with the short, the problem is not the compressor clutch, but most likely the relay, low pressure switch, fuse, etc.
If the A/C clutch does not work with the short in place, A/C clutch coil is most likely the problem."

Just found that. Good diag. differential. I'll have to give that a go.

 

The a.c. magnetic clutch is like $100 from eBay. It can be replaced without pulling the compressor from the engine. It takes a couple hours. Pretty easy job. Pull the tire. Pull the belt. Put in service mode to reach the a.c. wires. Boom. Done. A.c. again.

 

Thanks. Ya, I watched Mod Mini's video on this. Easy enough, just need the right C-ring pliers. Ordered a coil off eBay as it turned out to be that. I got an OPEN on pin 87. And putting VDC on pin 87 doesn't engage the clutch.

 

Yes the right pliers is critical - that snap ring gave me HELL when I tried to use just a generic pliers set. I ended up ordering a full set with both inner and outer snap ring pliers for about $20. The job was very easy after that. Don't skimp on the right tools - also an impact wrench for the little torx bolt is also very important - it won't budge without.