A/C expansion valve replacement

[connorb850]

I could not find a write-up on how to replace the A/C expansion valve under the dash. For those who have done this, does anything else need to be removed inside the car (see pics)? Will I need to loosen the lines somewhere in the engine bay in order to pull the valve off the evaporator?

[drivinfaster]

what makes you think this needs to be replaced?? and no, they are not an easy diy which is probably why there are not a lot of write ups about it.... that, and they seldom actually fail.



df

[connorb850]

I believe the valve is partially clogged/blocked. The system has no leaks and does work somewhat, but doesn't cool as well as it should. The compressor cycles off because the low side pressure drops too low above 2000 RPM. The high side seems to be reading slightly higher than it should as well.

The valve "looks" fairly easy to replace, but I'm mostly concerned about getting the lines out of the way.

[drivinfaster]

so you have gauges?? what is resting pressure?? what is the vent temp?? read this....it'll help... http://www.bimmerfest.com/forums/sho...d.php?t=611551




df

[connorb850]

so you have gauges?? what is resting pressure?? what is the vent temp?? read this....it'll help... http://www.bimmerfest.com/forums/sho...d.php?t=611551

Thanks, I will take a look at that link.

I don't remember where static pressure was reading, but can retest if needed. With the system running at idle, low side is reading high 20s and the compressor stays running. If RPMs are raised to 2-3k simulating cruising speed, low side drops into the teens and compressor cycles. High side ranged from 150-200 or so during testing. Ambient temps were low-mid 70s with relatively low humidity. Infrared temp gun at the vents was reading upper 40s at raised idle and low 40s at idle. At cruising speed, I can feel "bursts" of cold air from the compressor cycling. I'm almost certain the system has a full charge. I have some basic knowledge of automotive A/C systems, and to me the low side is getting too low and the high side might be a little high for these early season mild temps.

[EURO M3 CSL]

Thanks, I will take a look at that link.

I don't remember where static pressure was reading, but can retest if needed. With the system running at idle, low side is reading high 20s and the compressor stays running. If RPMs are raised to 2-3k simulating cruising speed, low side drops into the teens and compressor cycles. High side ranged from 150-200 or so during testing. Ambient temps were low-mid 70s with relatively low humidity. Infrared temp gun at the vents was reading upper 40s at raised idle and low 40s at idle. At cruising speed, I can feel "bursts" of cold air from the compressor cycling. I'm almost certain the system has a full charge. I have some basic knowledge of automotive A/C systems, and to me the low side is getting too low and the high side might be a little high for these early season mild temps.

Hello, sorry to bring up an old thread but my e36 is experiencing the same symptoms. Even at static the low side would be much higher than the high side pressure when they should be there same when engine is off. How was the diy?


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[dlhjimmy]

I'm also curious how the diy went. my low pressure side is pulling a vacuum and the expansion valve may be a source of blockage. Good luck!

[blckstrm]

This is a pretty big pain. You obviously need to have someone bleed the system first.

Second, to answer the original question no one answered, yes, you need to loosen the two bolts inside the engine bay against the fire wall to get the lines loose enough to get the valve out (or at least I had to. And it was still tough. I don't think this is optional). It's not easy to get in or out at all.

Third, you need to plan on replacing any o-rings that you break loose when you do this, since they probably won't seal properly after being broken loose. I did, and I still have to charge it once a year or so. I HATE letting anyone else work on my car, but this is one of those things that is easier to let a shop do, since if the system doesn't seal it's on them to redo whatever is leaking.