W222 S550 has no heat inside heater valve ?
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Senior Member
Joined: May 2016
Posts: 416
Likes: 91
G63/RR LWB/W222 S550
W222 S550 has no heat inside heater valve ?
My 15 W222 S550 is blowing cold air from the vents despite warming up. It’s been very cold here -7, -8 F and the car sits outside usually. I parked it inside the garage and the heat appeared to have been back but then stopped working again.
No lights or codes. Coolant level full. Engine warms up fine. I’m thinking it’ll be the heater valve. I ordered the valve and a common return line that usually fails too.
Will I need to do a coolant flush after this repair?
No lights or codes. Coolant level full. Engine warms up fine. I’m thinking it’ll be the heater valve. I ordered the valve and a common return line that usually fails too.
Will I need to do a coolant flush after this repair?
Super Member
Joined: Jun 2025
Posts: 784
Likes: 249
From: USA
Very likely the heater valve. Known issue. You will lose some coolant when you swap it, so have new MB coolant ready to top up. A full flush isn't strictly necessary, but it's a good chance to do it if the coolant is old. The trapped air is the real problem. You'll need to properly bleed the cooling system after to get the heat back.
