A/C diagnostics, lots of info w/pics

Originally Posted by trizzuth

damn bro, you should open up a shop to diagnose/fix A/C problems with all the knowledge and tools you have now!

Nervous - great work! Very thorough. How about putting the link in your sig to make it easy to find, after it slides off Page 1?

Do you know roughly what you had to spend on specialized gear - manifold, vacuum pump, etc.?

Thanks for taking the trouble to do all the pics and the write-up...

Thanks, I've put my DIYs into my sig.

As to the cost of tools:

• Mastercool 99872A Digital R-134A Manifold Gauge Set, $128.79, automotivetoolsonline.com
• Robinair 15500 VacuMaster 5 CFM Vacuum Pump, $169.19, amazon.com
• Mastercool Flush kit (MAS91046-A) $32.95, tooltopia.com
• Mastercool 85510 R134a Can Tap Valve-Screw-On Model, $8.84, amazon.com
• scales (already had)

Supplies:

• One Bottle 8oz Refrigerant Oil FJC PAG 46 A/C R134a Oil, $12.15, amazon.com
• Two bottles of FJC Flush solvent FJC2405, $11.19ea, tooltopia.com (actually, I needed only one)
• 3 cans of R134a refrigerant, $9.97 ea, Walmart

Parts:

• Condenser (TYC, from rockauto.com) - $90
• dryer (autohausaz.com) - $37
• expansion valve (autohausaz.com) - $40
• pressure sensor (rmeuropean.com) - $41
• New LOW and HIGH shrader valves (bmwmercedesparts.com) - $8.76ea
• Inline filter (http://www.auto-air-compressor.com/In_Line_Filter.html) - $38
• O-rings from different vendors (autohausaz and rmeuropean, mostly) - don't remember how much, but not a lot.

Hey nervous good info here but there are a couple of things that i need to point out, pressure and temp are pretty close so when reading psi think temperature as well so

First, when checking the static pressures they should be about the same as ambient temps and the hi side and low side should be the about the same make sure system is not on or has not been operated

Second, when checking pressure with the system running you should check them with the blower at max speed and engine at 1500 to 2000 rpms.

Third, hi side pressures are based on ambient temp and there is a formula for getting your specs its 2.42 x Ambient temp for min hi side spec and 2.4 x Ambient temp + 50 to get your max hi side spec.

Fourth, the expansion valve(h valve) is normally set to operate the system between 10-30 psi there perfect at 22psi. Anything higher and there is either to much refrigerant or oil or not enough air flow to the condenser causing pressures to go up. Diagnose from the hi side because the metering device does a good job of compensating for low or too much refrigerant and will keep the low side in spec or close to spec

I'm no a/c expert by any means i just have some knowledge from school and just trying to input what i know.

Cool, thanks a lot for adding valuable info!

This is all excellent information, thanks for all of the hard work Nervous, as well as taking the time to show us all the process and results!

Quick note... your INPA images from Post #3 are not loading, any way to fix that?

I don't feel like my AC has ever really run to its full potential... I will use this thread as a guide when I get around to checking each component.

Hmm, no idea why some of my pics are lost and I can't edit my post. So, here are the lost images:
Post #1:

Post #3:



Post #4:

Excellent sir, thank you!

I applaud your organizational skills, for I can only assume that to reply with the missing photos within minutes, they must be stellar.

amazing work! this is going to be my next overhaul

So Nervous, what would you say was the root cause of your A/C problem?

nervous...do you have a copy of the temperature/pressure reading. BMW AG told spagetti code reader to remove their TIS so now we have one less resources to view on the internet =(

BMWCaptain, sorry missed your question. I bet it was the pressure sensor mounted on top of the drier.
flashmeow, I'll try not to forget and make screenshots with this info from my TIS.

Here it is, TIS info about pressures: https://docs.google.com/open?id=0BwF...1RDYlpiYlVma1E

Originally Posted by Nervous

Here it is, TIS info about pressures: https://docs.google.com/open?id=0BwF...1RDYlpiYlVma1E

thank you! you got yourself a gold star for today's contribution to the community