Air conditioning intermittently not cooling

Josep Technical Support Specialist New York Posted   Latest   Edited  
Tech Tip
2006 Mercedes-Benz ML350 Introduction 3.5L (272.967) 7-spd
Intermitent A/C Operation

Watch out for all Mercedes with poor operating a/c. The refrigerant hoses contain an internal vinyl sleeve. This sleeve can come loose from the rubber line and can cause a permanent or occasional restriction.

If the low side pressure is noticeably high, use an infrared temp gun to check for a temperature drop in the line. 

If you have a temperature drop in a line that shouldn’t have one, this may be your problem.

James Diagnostician


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Allan Instructor

Hello Josep, R134a systems use barrier hoses with a liner. This could happen to any R134a system. It looks like damage from some sort of additive, most likely a seal conditioner that is supposed to stop leaks in the system by swelling the O-rings. These "Wonder Cure" additives cause all kinds of damage to A/C systems, unfortunately the damage takes a while to manifest itself. So someone adds

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