Recharging AC

SABRINACG

MEMBER
2008 MERCEDES BENZ E350
V6
4WD
AUTOMATIC
98,000 MILES

Yesterday my AC was working just fine, but today it is blowing warm air. I wanted to try and recharge the AC with an AC Pro. My question is, there are two valves, which one is the low pressure service valve? Is it the valve closest to the coolant reservoir on the right hand side? Or the valve closer to the windshield? Thank you!

3 Replies

STEVE W.

MECHANIC
13,463 POSTS

If it was working fine yesterday and today it is not then it is very likely that it is not the loss of the 134A in it that has caused the failure. The only way for that to be the cause would be a very large leak which would just leak out the new charge as fast as you could add it to the system. Much more common are failures in the pressure sensors or the automatic temperature controls. Adding more 134A can do serious damage to parts that are very expensive ($2,000.00 to $3,000.00) to replace.

When you set the temperature to cold with AC on what do the lights on the HVAC control panel do? Mercedes did not include much for self testing but if the LED's flash on the controller it has detected a fault. There are many others that it will not show any indication for however. For those you need to have a scan tool.

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Friday, June 29th, 2018 AT 5:08 PM

SABRINACG

MEMBER
2 POSTS

There are no lights or indicators popping on, no.

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Friday, June 29th, 2018 AT 8:36 PM

KEN L

MASTER CERTIFIED MECHANIC
47,633 POSTS

Okay, lets plug the charge kit on to see if there is pressure in it. Here is a video to helps you see how to do the job:

https://youtu.be/uZrQCGwXfek

This guide can help as well.

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

Please run down this guide and report back.

Cheers, Ken

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Monday, July 2nd, 2018 AT 1:20 PM