AC only Hot Air 2017 GLS
Thread Starter
Junior Member
Joined: Apr 2019
Posts: 54
Likes: 1
E350
AC only Hot Air 2017 GLS
2017 GLS 450 96k.
The AC stopped working all of a sudden took it to a couple of shops the refrigerant is perfect and the compressor does kick in but the car constantly blows hot air. All events below the same amount of temperature so I'm wondering if it's not the freon not the compressor how do I check to see if the control unit is operating? All the buttons are lighting up as they should be the defrost kicks in and the vents blow up against the windshield the max button initiates the blower at full speed but no cool air. Has anyone experienced this issue?
The AC stopped working all of a sudden took it to a couple of shops the refrigerant is perfect and the compressor does kick in but the car constantly blows hot air. All events below the same amount of temperature so I'm wondering if it's not the freon not the compressor how do I check to see if the control unit is operating? All the buttons are lighting up as they should be the defrost kicks in and the vents blow up against the windshield the max button initiates the blower at full speed but no cool air. Has anyone experienced this issue?
MBWorld Fanatic!
Joined: Jun 2021
Posts: 1,919
Likes: 522
From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
Find where the AC lines go through the firewall or into the ventilation system and see if they are getting cold. If they are, the problem is in the control or the motors that operate the vent dampers. If not then it's related to the refrigeration system. Did the shop that blessed the refrigerant as "perfect" check the operating pressures? If they are "perfect" too then it's likely you're getting air from (only) the heater instead. Did you try setting everything to maximum cool?
MBWorld Fanatic!
Joined: Jun 2021
Posts: 1,919
Likes: 522
From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
That one should be cool if not cold when the AC is running. It says "Suction" which men it's the return line from the evaporator (cold) to the compressor. It also has the low pressure test fitting on it.
Trending Topics
MBWorld Fanatic!
Joined: Jun 2021
Posts: 1,919
Likes: 522
From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
It's complicated. There are two pressures, "low side" and "high side". They are both important. here's an over simplification:
If both are low it's under charged. If both high it's over charged. Too close to each other and the compressor is probably weak. Too far apart and there's a blockage.
If both are low it's under charged. If both high it's over charged. Too close to each other and the compressor is probably weak. Too far apart and there's a blockage.
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
MBWorld Fanatic!
Joined: Jun 2021
Posts: 1,919
Likes: 522
From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
Junior Member
Joined: Oct 2023
Posts: 18
Likes: 1
2017 GLS 550
Related question. I also have a 2017 GLS 550. Purchased used 3 years ago. Entire time I've owned the vehicle, upon startup the A/C blows hot for 3-4 minutes, and then cold and cools the car fine. Is this normal? How long do others experience before the A/C blows cold? If not normal, things to check?
Thanks, Dave.
Thanks, Dave.
MBWorld Fanatic!
Joined: Jun 2021
Posts: 1,919
Likes: 522
From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
Sounds similar to ours. Maybe not 4 minutes, but at least 2. Seems longer than usual. My guess is there's a temp sensor on the evaporator and it doesn't route air through there until it's "cold enough".
Member
Joined: Jul 2015
Posts: 139
Likes: 36
2017 GLS 550
Related question. I also have a 2017 GLS 550. Purchased used 3 years ago. Entire time I've owned the vehicle, upon startup the A/C blows hot for 3-4 minutes, and then cold and cools the car fine. Is this normal? How long do others experience before the A/C blows cold? If not normal, things to check?
Thanks, Dave.
Thanks, Dave.
Member
Joined: Nov 2018
Posts: 139
Likes: 37
From: Portland, OR
GL320 CDI
Dealership - $3500
Independent shop - $1800
DIY - $600 + AC recharge
Thread Starter
Junior Member
Joined: Apr 2019
Posts: 54
Likes: 1
E350
Why people take 10yr old European cars to the dealership and pay their incredible prices is beyond me. A dealership wants to fix problems by replacing all the old parts with new parts. An independent shop wants to diagnose and resolve problems so they don’t have frustrated customers.
Dealership - $3500
Independent shop - $1800
DIY - $600 + AC recharge
Dealership - $3500
Independent shop - $1800
DIY - $600 + AC recharge
MBWorld Fanatic!
Joined: Jun 2021
Posts: 1,919
Likes: 522
From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
It's never a bad idea to change the dryer any time the system is opened. If the system has been opened or out of Freon for any length of time then replacing it is a must.
MBWorld Fanatic!
Joined: Jun 2021
Posts: 1,919
Likes: 522
From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
I can't think of a reason it would be more than $200 extra. The part is about $165. (Compressor is around $1000 for the part.)
Try somewhere other than the dealer!
Try somewhere other than the dealer!
Super Member
Joined: Dec 2007
Posts: 846
Likes: 45
From: ATL
2017 GLS 550
you can get a full kit with a Remanned compressor, dryer, all the o-rings and new expansion valve for less than $300 on Ebay. replace everything yourself, drive it to an A/C shop tell them it is all new with no oil, have them vacuum it down, add oil and refrigerant... and you are golden!
or from FCP new Genuine Mercedes Compressor just under $1k, expansion valve is $61, and I can't find a drier on FCP so you will have source that elsewhere.
or from FCP new Genuine Mercedes Compressor just under $1k, expansion valve is $61, and I can't find a drier on FCP so you will have source that elsewhere.
Newbie
Joined: Jul 2025
Posts: 13
Likes: 0
From: Chicago area
2017 GLS 450
you can get a full kit with a Remanned compressor, dryer, all the o-rings and new expansion valve for less than $300 on Ebay. replace everything yourself, drive it to an A/C shop tell them it is all new with no oil, have them vacuum it down, add oil and refrigerant... and you are golden!
or from FCP new Genuine Mercedes Compressor just under $1k, expansion valve is $61, and I can't find a drier on FCP so you will have source that elsewhere.
or from FCP new Genuine Mercedes Compressor just under $1k, expansion valve is $61, and I can't find a drier on FCP so you will have source that elsewhere.
I also have a 2017 GLS 450 that is not blowing cool air. I am almost at the point of buying the parts. I have 2 questions:
1. How do I determine if my compressor has an Electronic Control Valve or a Clutch? If I recall correctly, when I turn off the AC using the dash buttons, I can tell that the compressor is quieter, which I think might mean it has a clutch. It is hard to see and has dirt/oil on it, which also makes it more difficult.
2. When I look at sites like MBoemparts.com I see several compressors listed. How do I know which one to purchase? I did enter my VIN. Most if not all of the compressors available are reman. here is the link... Refrigerant Compressor for 2017 Mercedes-Benz GLS 450 | MB OEM Parts
Thanks!!
