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Lou
10-03-2006, 11:28 AM
OK now, I'm stumped and annoyed. Sometimes when I've got he heater/AC on vent with the temp. set at 60 degrees all of a sudden I start getting hot air out of the vent as if I had the temperature turned up.

I ran the EATAC self diagnosis and it came back that everything was OK.


If I turn the A/C on for about a minute and then back to vent it works fine.

Any ideas on what's wrong or how to fix it? :help:

Mine is an '04 MM with less tha 26K miles.
fastblackmerc
10-03-2006, 11:40 AM
Most likely it's the HVAC head unit (in the dash).
magindat
10-03-2006, 11:49 AM
Most likely it's the HVAC head unit (in the dash).

If it's when you accelerate, it could be a vacuum issue.
Lou
10-03-2006, 12:58 PM
Most likely it's the HVAC head unit (in the dash).


If that were the case why would the self-diagnostic come back showing no problem? :help:
Peter
10-03-2006, 01:17 PM
If that were the case why would the self-diagnostic come back showing no problem? :help:

Err Computer Error?
magindat
10-04-2006, 06:57 AM
Err Computer Error?

Not likely. I still vote there's a cracked or disconnected vac line somewhere.
SergntMac
10-04-2006, 07:13 AM
Under half/WOT, the AC compressor shuts off. Any relationship with loss of AC and the on ramp?
magindat
10-04-2006, 09:01 AM
Under half/WOT, the AC compressor shuts off. Any relationship with loss of AC and the on ramp?

Very true, but I think he said on 'Vent'.
Grifter
10-04-2006, 10:14 AM
OK now, I'm stumped and annoyed. Sometimes when I've got he heater/AC on vent with the temp. set at 60 degrees all of a sudden I start getting hot air out of the vent as if I had the temperature turned up.

I ran the EATAC self diagnosis and it came back that everything was OK.


If I turn the A/C on for about a minute and then back to vent it works fine.

Any ideas on what's wrong or how to fix it? :help:

Mine is an '04 MM with less tha 26K miles.

is the climate control set to "Automatic"?
if it is, theres your issue. the Automatic setting tries to keep the cabin at whatever temp you have the climate control set to. if it detects its too cool, it throws heat.. if it detects too hot, you get cool air.. the fan also acts the same way, it will speed up/slow down as needed..
RR|Suki
10-04-2006, 10:24 AM
OK now, I'm stumped and annoyed. Sometimes when I've got he heater/AC on vent with the temp. set at 60 degrees all of a sudden I start getting hot air out of the vent as if I had the temperature turned up.

I ran the EATAC self diagnosis and it came back that everything was OK.


If I turn the A/C on for about a minute and then back to vent it works fine.

Any ideas on what's wrong or how to fix it? :help:

Mine is an '04 MM with less tha 26K miles.

take it to the dealer, warranty is there to be used, so use it while you can...
Lou
10-04-2006, 10:30 AM
Under half/WOT, the AC compressor shuts off. Any relationship with loss of AC and the on ramp?

Nope Sgt. only happens on vent.
Lou
10-04-2006, 10:32 AM
is the climate control set to "Automatic"?
if it is, theres your issue. the Automatic setting tries to keep the cabin at whatever temp you have the climate control set to. if it detects its too cool, it throws heat.. if it detects too hot, you get cool air.. the fan also acts the same way, it will speed up/slow down as needed..


Nope, it only happens when I don't have the A/C on and I hardly ever use the automatic setting. So far I've only notinced it on vent but my guess "floor" would do the same thing.

Thanks for all the help guys. As one suggested, i should probably take it to the dealer but it's my daily driver and it's a pain to be without my baby for a day.