AC Blows Cold, then Warm (Thoughts?)
Thread Starter
Senior Member
Joined: Feb 2011
Posts: 498
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From: South Florida
1998 C43, 2017 Honda Accord Sport
AC Blows Cold, then Warm (Thoughts?)
Hey folks,
Recently, I've developed an odd problem where every time I start the car, it blows cold, however, as the engine warms up, the AC blows warmer (never hot, just ambient/warm).
On a side note, I've replaced the following within the last 6k miles before I got this problem; I've also not had this problem for a solid year after these parts were replaced (so a leak is not likely): AC compressor, receiver drier, and condenser (with a full freon evac and recharge of course).
I'm thinking either 1) duo control valve (my mechanic surmises this is the culprit after he took the car for a quick spin; he installed the aforementioned AC components) or 2) expansion valve.
Thoughts? Has anyone had one of these components fail?
Recently, I've developed an odd problem where every time I start the car, it blows cold, however, as the engine warms up, the AC blows warmer (never hot, just ambient/warm).
On a side note, I've replaced the following within the last 6k miles before I got this problem; I've also not had this problem for a solid year after these parts were replaced (so a leak is not likely): AC compressor, receiver drier, and condenser (with a full freon evac and recharge of course).
I'm thinking either 1) duo control valve (my mechanic surmises this is the culprit after he took the car for a quick spin; he installed the aforementioned AC components) or 2) expansion valve.
Thoughts? Has anyone had one of these components fail?
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From: Land of mountains, cheese, chocolate and watches
12' W204 C63 AMG coupe "T-Rex", 12' W451 Smart Fortwo Pulse (99' W202 C43 AMG + Ultima Can-Am sold)
Could indeed be a sticky duo-valve. Sometimes tapping (gently with a soft head hammer) the side of each cylinder may free the sludge and faulty piston. If not, you can remove and clean out the gunk inside. They a a bit expensive new, ar least in my part of the woods, so be careful 
Thread Starter
Senior Member
Joined: Feb 2011
Posts: 498
Likes: 7
From: South Florida
1998 C43, 2017 Honda Accord Sport
Could indeed be a sticky duo-valve. Sometimes tapping (gently with a soft head hammer) the side of each cylinder may free the sludge and faulty piston. If not, you can remove and clean out the gunk inside. They a a bit expensive new, ar least in my part of the woods, so be careful
I can always take apart the old one and see, after I swap the new one in. They're ~$150 USD here; not too bad given the price of other components for Mercedes.
Thread Starter
Senior Member
Joined: Feb 2011
Posts: 498
Likes: 7
From: South Florida
1998 C43, 2017 Honda Accord Sport
Update: Replaced the duo control valve - still ambient air :/
I checked fuses and the compressor to verify correct operation. I guess I probably need a recharge (and/or a leak fixed) which I find hard to believe. Off to the dealer I guess to get a full AC inspection.
I checked fuses and the compressor to verify correct operation. I guess I probably need a recharge (and/or a leak fixed) which I find hard to believe. Off to the dealer I guess to get a full AC inspection.
MBWorld Fanatic!
Joined: Mar 2010
Posts: 5,889
Likes: 323
From: Land of mountains, cheese, chocolate and watches
12' W204 C63 AMG coupe "T-Rex", 12' W451 Smart Fortwo Pulse (99' W202 C43 AMG + Ultima Can-Am sold)
If your baby is loosing HEVAC gaz, my quick suggestion would be to check the stuff which will have accumuladrd between coolant radiator and condenser. I had sufficient dirt, schmuck, leaf and twigs to start a veggs garden
Thread Starter
Senior Member
Joined: Feb 2011
Posts: 498
Likes: 7
From: South Florida
1998 C43, 2017 Honda Accord Sport
Not that, as I got in an accident the other year and got the whole front end rebuilt. It's been garaged and super pampered ever since (and only 3-4k miles since). Everything is clean.
