08 Boxster ac compressor

[vza]

Hi All, Ac wasn't working few months back clutch wasn't engaging...I thought because of a leak and low refrigerant. Replaced an ac pipe, receiver dryer and expansion valve. Pulled vacuum and charged, was working...could have been cooler. That was during the winter in the garage ( northeast). Now suddenly its blowing a B10 25A fuse. Disconnected the compressor wire figuring it was the compressor but it's still blowing fuses. Thoughts? Thanks V

[JFP in PA]

B10 is the fuse for the AC clutch, amongst other circuits (Instrument Cluster Diagnosis Mirror Adjustment (to 1997)Headlight Vertical Aim Control (from 1999)ALWR (from 2001)Parking Assistant (from 2001)
.

[vza]

So your saying it's another component?

V

[JFP in PA]

No, not without further electrical diagnostics.  It could still be the compressor clutch, but you need to do some testing to find out.

[vza]

Ok what do I do?😁

I already disconnected the compressor wire but it still blew. The hvac controller goes out as well w the blown fuse. 

Edited June 25 by vza

[JFP in PA]

You need to start checking circuits, relays, and the controller for excess amperage draw, shorts, etc.

[Vincent Venezia]

Umm.....not too sure where to start. Tested the ohms on the compressor clutch it was 3.5ish which i think is in the good range.

The AC relay I think is in the back trunk, slot #1? What next? V

Edited July 1 by Vincent Venezia

[JFP in PA]

You need to be testing total amperage draw on the circuits; for that, I use what is called a DC "clamp" meter that senses the draw on an active circuit, it simply clamps around the wire under test and shows you how much current (amps) is being pulled:

 

[vza]

I figured I would disconnect associated components to find which is the bad one...since I'm not too inclined to find wires to test amps. I swapped the ac relay w new one thats located in left rear trunk, disconnected cooling fan control module, disconnected ac low press switch and ac compressor. Head unit remained on and was able to activate all switches.  Fuse began blowing when I plugged the low pressure switch in. Not sure what that means...don't think it's the switch I think it just supplies 12v to the compressor and the compressor does go on(clutch engages) when it's plugged in but then immediately blows a fuse which makes me think it's the compressor. After that I checked resistance on ac clutch coil by putting a meter between wire coming off compressor and ground I got over 8 ohms which is out of spec. Thoughts? V

Edited July 15 by vza

[JFP in PA]

If the low-pressure switch causes the fuse to blow, that is your questionable circuit.  The low-pressure switch is a safety that prevents the clutch from engaging when the gas pressure in the system is too low, so it normally allows current to flow to the clutch.  It could be the switch, or the circuit running from the switch to the clutch is shorted.

[vza]

So if I jump the low pressure switch bypassing it allowing the compressor to run and it doesn't blow a fuse then I know it's the switch. There's 3 terminals in the switch I know one is hot. How do I jump the switch. Of course if it blows a fuse then I guess it's wiring issue. V

[JFP in PA]

You will need a wiring diagram for the car to identify which terminals are which.

[vza]

Ok...but I'm correct in assuming that about the outcome?

 

[JFP in PA]

Yes.

[vza]

So jumped the connector side of the low press switch and ac clutch did not engage.(I tried every combo in switch) 

I have no power at the low press. switch, engine running ac switched on...only millivolts

Ac clutch clicks when V applied direct from batt. 

Now...head unit is not blowing fuses w low press switch connected and ac on car running but the clutch no longer engages. Before if ran and blew fuses immediately.  

Tried locating  ac freeze switch but couldn't find it. I read the freeze,switch sends voltage to low press switch.

I also jumped the compressor straight from the battery and ran the AC with the engine on the compressor ran but it sounded like it was laboring the engine a little more than normal the temp got a little cooler but not that much

Anything????

Edited July 15 by vza

[JFP in PA]

To my knowledge, there is no separate "ac freeze switch" in the Boxster's; many of the earlier analog cars (944. 924, 928) had a temp sensor in the heater box area to prevent the system from icing over in high humidity environments, but the later cars like the Boxster used the digital climate control system in the dash to accomplish the same end without a separate sensor for the purpose.

[vza]

 

Is there supposed to be 12v at the low press switch I thought for sure I got 12v yesterday but today there wasn't any voltage as stated earlier. So it seems now no voltage to the compressor. That's why it's not blowing fuses now. Days earlier when tested the ac clutch would engage and immediately blow a fuse. Now the clutch is not engaging and therefore not blowing a fuse. 

Edited July 16 by vza

[JFP in PA]

You probably have a fault in the climate control module in the dash that is preventing the correct voltage supply to the compressor clutch.

[Vincent Venezia]

I tried 2 of them....they both were blowing fuses....when it used to blow fuses anyway...V

[JFP in PA]

At this juncture, I would have the car scanned with a legitimate PIWIS system, which can see and test multiple components in the AC system, including control modules.

[vza]

Funny I was thinking the same. Bring it in and have it checked. Thanks V

[JFP in PA]

People often forget that legitimate PIWIS systems can test and activate individual components that no other scan tool can even see on these cars.