2002 Q45 A/C not cold enough - HELP needed

[q45inca]

hi, I've owned this car for 12 years (the best car I have ever owned - and I've owned many cars including top of the line from the best German and Italian brands). But it has always had one problem, a/c which has been cool, not cold. I've had the a/c serviced several times, always with the same answer: it has been re-charged now and it's working fine, the temperature at the vents is within the norm etc. I've had the filters changed, washed the radiator, checked low and high pressure and they were good etc. So nothing seems to be wrong, but a/c is not really cold. (BTW, in winter the heat is never really hot either).

It gets better with a high speed driving, so except for Death Valley it's ok for highway driving even during a hot summer, but in stop and go city driving with 100F plus outside, you may as well say it's blowing warm air.

I'm not fussy myself (hence 12 years driving like that :-) , but I've given the car to my kid now, and teenagers nowadays don't have much resiliency and she says she can't use it.

So before I replace everything, what is the most likely problem? How can I make the a/c as cold as in any new cheap car the kids are used to? (the cheap cars work the best for a/c and heat as they don't have any fancy brains which always seem to get in the way :-)

Any help greatly appreciated!!! thanks

[Q451990]

If you set it down to the lowest possible setting, does it get cold enough then? There is a +/- 6 degree adjustable trim to the temperature setting, so you could try adjusting that. In other words, that would have the system trying to hit a 6 degree colder target than is displayed... Automatic climate control is definitely different than a standard car a/c where you set it on "hang icicles from the roof cold" and let it groan away. I have an adjustment period between my truck and the Q. You can see how to adjust the trim in the factory service manual available at www.infinitiservicemanual.com on page ATC-56. There are a number of other diagnostics you can run to see if everything else is functioning normally too.

[q45inca]

It's set to the lowest possible setting most of the time, and it is not cold enough. Adjusting that 6 degrees would definitely help - I'll give it a try. I have a feeling that it's some sort of "too smart" programming which wants to make temperature "comfortable and not too cold" which is not working quite right with some sensor malfunction or something like that... I wish that the "luxury" cars could also be equipped with a fully manual a/c and heat controls, or perhaps there is some way to wire the Q like that? thanks!

[q45inca]

BTW, so should the trimmer be set to -6 or +6 to make it the coldest? thanks

[Q451990]

I would think -6. I'd run the other diagnostics just to see if there's another malfunction. My guess is that your problem is more related to a system issue... not enough or too much refrigerant, dirty coils, dirty condenser, something like that - but you're saying all of that's been checked. I guess it comes down to how much you trust the technician that checked it.

[q45inca]

Thanks, I'll run the tests and if the trimmer does not help much I will have it re-checked by a dealer or someone specializing in this type of a car - I've been taking it to a nearest general repair mechanic. I don't think he is a big expert here.

[ArmedAviator]

When you say the system was "re-charged", the tech purged the system them refilled to proper quantity, right? Over-filled can cause many issues as well, although should be noticeable with a manifold gauge which you said you checked.

Check blend door operation. You mentioned it doesn't get quite hot enough when commanding hot air.....perhaps the blend door isn't moving to its full limits.

[JoshuaM]

From your description, it's necessary for a professional checking.

[Rixmax1992]

I had the same problem it turned out to be the mixing door. This was definitely a problem for the dealer to handle.

[q45inca]

thanks!