HEVAC playing up?
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12' W204 C63 AMG coupe "T-Rex", 12' W451 Smart Fortwo Pulse (99' W202 C43 AMG + Ultima Can-Am sold)
HEVAC playing up?
The temperatures are finally looking like real summer and with the rise of the heat I had my A/C checked and refilled. It had lost some gas since last year same time approximately. I think the compressor is getting on in age as it looks like OE factory fitted and when using a UV light, I can see some traces of the fluorescent dye around the unit. So I guess there must be a small leak, but not enough to stop proper operation.
Previously when the cabin was very hot after a spell in the sun, when I switched the engine on, the settings of the HEVAC on Auto, the fan would kick in and work up to full speed quickly. The led screen on the HEVAC control unit shows the max speed reading. A short time later after 10 secs approx, the vents would shoot out blasts of cold air over the fan's full speed, like if a second fan kicked in. This way the cabin could cool quickly and a short time later the fan would gradually reduce speed so that the occupant(s) didn't freeze!
Already last year this extra cold blast didn't work regularly. You could clearly hear it cutting in and out, but now it no longer does it.
Any ideas what could be the problem? Could it be the fan's regulator as I assume the fan has one?
I may scan and see if any codes show up
Previously when the cabin was very hot after a spell in the sun, when I switched the engine on, the settings of the HEVAC on Auto, the fan would kick in and work up to full speed quickly. The led screen on the HEVAC control unit shows the max speed reading. A short time later after 10 secs approx, the vents would shoot out blasts of cold air over the fan's full speed, like if a second fan kicked in. This way the cabin could cool quickly and a short time later the fan would gradually reduce speed so that the occupant(s) didn't freeze!
Already last year this extra cold blast didn't work regularly. You could clearly hear it cutting in and out, but now it no longer does it.
Any ideas what could be the problem? Could it be the fan's regulator as I assume the fan has one?
I may scan and see if any codes show up
Last edited by DRBC43AMG; Jun 19, 2019 at 02:58 AM.
Thread Starter
MBWorld Fanatic!
Joined: Mar 2010
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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)
MBWorld Fanatic!
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From: A.D., U.A.E
2000 (W202 C200) & 2000 (W202 C55)
Many things could cause this Daniel,
less or gas leak/bad tank sensors/bad Evap. indoor sensor/malfunction of climate control unit/bad compressor magnet"..!,,
did you diagnose the car..?, any codes of A/C system would help..
-;ZAYED;-
less or gas leak/bad tank sensors/bad Evap. indoor sensor/malfunction of climate control unit/bad compressor magnet"..!,,
did you diagnose the car..?, any codes of A/C system would help..
-;ZAYED;-
Thread Starter
MBWorld Fanatic!
Joined: Mar 2010
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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)
No, not yet done any scanning. I'm a bit handicapped by a knee accident which happened yesterday evening. Walking and moving around is painful and I can't drive for a couple of days. If I can get down to the garage, I'll try scanning and pull the codes tomorrow or Friday.
MBWorld Fanatic!
Joined: Aug 2006
Posts: 7,053
Likes: 398
From: A.D., U.A.E
2000 (W202 C200) & 2000 (W202 C55)
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12' W204 C63 AMG coupe "T-Rex", 12' W451 Smart Fortwo Pulse (99' W202 C43 AMG + Ultima Can-Am sold)
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Thread Starter
MBWorld Fanatic!
Joined: Mar 2010
Posts: 5,892
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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)
Pulled the codes this morning and nothing at first glance which would be HEVAC related. Seems the left O2 sensor is not working as it should, but it still passed the emissions test end of May.
I need to run the diagnosis of the HEVAC from the screen on the dash
I need to run the diagnosis of the HEVAC from the screen on the dash
Thread Starter
MBWorld Fanatic!
Joined: Mar 2010
Posts: 5,892
Likes: 324
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)
Thread Starter
MBWorld Fanatic!
Joined: Mar 2010
Posts: 5,892
Likes: 324
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)
Easy, I searched on the page using the word HEVAC
Thread Starter
MBWorld Fanatic!
Joined: Mar 2010
Posts: 5,892
Likes: 324
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)
Looking in my dossier for error codes identification documentation, I came across a print-out which I pulled from this thread from 2010 ritten by our "white coat tech" 
https://mbworld.org/forums/c36-amg-c...on-button.html
https://mbworld.org/forums/c36-amg-c...on-button.html
