poor a/c performance

[ichoplin]

I know this topic is not new, and I read a ton of threads on this but here it goes anyway.

Here in Okla, we are beginning to warm up(90deg) and the a/c in my 06QC is not up to snuff. In my truck, it's not that the air isn't cold, it's just that there isn't enough of it. I ended up having to run the fan on high and the noise. Man, the noise from that fan is crazy.

In the other threads I read, guys mentioned their recric door. I can actually hear mine close when I set the dial to recirc. So, maybe that rules that out.

This past winter, I changed the defrost door and at the time the other doors worked properly. Could there be a blockage somewhere that I'm missing? Low refrigerant like a lot of others have seen? I'll definitely use a dial-type thermometer today while I'm out to check what's actually coming out of the vents. What do you all think?

Thanks,

Ian

 

[AWise]

If the fan is noisy i would suspect that something is in the fan or blocking it, most likely the recirc door. Takes on a couple minutes to double check to rule it out. Take out the 3 screws that hold the fan motor in and look to see if there is a small chunk of plastic in it. Also look up in there and make sure the door is in place and not laying across the opening. Mine was super loud when my recirc door failed, took 5 minutes to get it out.

 

[ichoplin]

Thanks AWise,

I pulled my glove box and my recirc door was still in place. I thought it would be as I can hear it close.

Check out what I found above the recirc door, a nasty screen. Don't know if any of you followed my thread concerning my engine cooling problems or not, but this dirtiness shouldn't surprise me. From all my digging around on this truck(new to me in Oct09), I figure its previous life was spent strictly on dirt roads.

Anyway, are there more of these screens up in there? I ran the a/c just to see and it "seems" better. Won't know for certain until it warms up a little.

How's my temp considering it's only 80deg outside?

Thanks,

Ian

 

[LRutigliano]

Thanks AWise,

I pulled my glove box and my recirc door was still in place. I thought it would be as I can hear it close.

Check out what I found above the recirc door, a nasty screen. Don't know if any of you followed my thread concerning my engine cooling problems or not, but this dirtiness shouldn't surprise me. From all my digging around on this truck(new to me in Oct09), I figure its previous life was spent strictly on dirt roads.

Anyway, are there more of these screens up in there? I ran the a/c just to see and it "seems" better. Won't know for certain until it warms up a little.

How's my temp considering it's only 80deg outside?

Thanks,

Ian

Your vent temp is just about perfect. Any colder and you run the risk of having a frozen evaporator core.

 

[tempforce]

looks like you found what was causing the lack of air flow... .

 

[ichoplin]

Update: my a/c is still pathetic. 85deg, fan on 3rd setting, and I'm sweating my tail off. The temp from my vent was approx 55deg. I believe it's cold enough, but the airflow just isn't there.

Is there a cabin air filter on these?

Anywhere else I should check for obstructions? I'm fairly confident that all the doors in the hvac are working.

Thanks,

Ian

 

[tempforce]

check the air inlets, fan blades, anything that the mud/dirt can stick onto.
my little truck's fan was making noise and wasn't blowing air. until after spending a winter in arizona then while driving on a real bumpy road, the dirt let go. you should of seen all of the dirt and needles that came out of the vents.
my fan works great now...

 

[ichoplin]

The wife is pressuring me to do something about this a/c situation. I told her I read here that some guys' trucks were low on refrigerant. I bought one of those cans that comes with the pressure gauge.

I followed the instructions on the can and am not sure what to make of it. I mean, the pressure fluctuates up and down as the compressor kicks on and off. Do I go by the highest pressure reading when the comp. kicks on? Or the lowest when it's off? The pic is a little fuzzy, but it shows approx 20psi on this gauge. It goes as high as 40'ish.

I just want to be sure I don't cause any damage. My wife's Pathfinder's a/c will freeze you out with the fan on level 2. My truck, you are sweating no matter what fan speed is being used. Is that dirty screen I showed the only one? I don't remember my 04 being like this. I know the two 02's I've had were plenty cool.

thanks,

Ian

 

[LRutigliano]

The wife is pressuring me to do something about this a/c situation. I told her I read here that some guys' trucks were low on refrigerant. I bought one of those cans that comes with the pressure gauge.

I followed the instructions on the can and am not sure what to make of it. I mean, the pressure fluctuates up and down as the compressor kicks on and off. Do I go by the highest pressure reading when the comp. kicks on? Or the lowest when it's off? The pic is a little fuzzy, but it shows approx 20psi on this gauge. It goes as high as 40'ish.

I just want to be sure I don't cause any damage. My wife's Pathfinder's a/c will freeze you out with the fan on level 2. My truck, you are sweating no matter what fan speed is being used. Is that dirty screen I showed the only one? I don't remember my 04 being like this. I know the two 02's I've had were plenty cool.

thanks,

Ian

I think you have the pressures backwards. When the compressor kicks on, the pressure should be 20psi because the compressor is pulling the system down. With the compressor off, you should be reading 40psi because the system is equalizing between the high and low side.

 

[ichoplin]

So that means my pressures are ok?

Ian

 

[LRutigliano]

So that means my pressures are ok?

Ian

If you are reading it backwards, then that means your low side pressure is too low. It should in the 35 to 50psi range on a warm/hot day with the compressor on. 20 psi means you are low on refrigerant.

 

[ichoplin]

Now I'm confused. Firstly, I admit I know nothing of how the a/c system works other than through evaporation.
So maybe when I say my comp kicks on, the gauge should go down, right? At that time, is 20'ish psi ok? Or am I all backwards? When the comp kicks off, it goes up to 40'ish. Is that normal?
thanks for the patience,
Ian

 

[Delrayz]

At ambient temp of 70-80 vent temp should be 45 and low side pressure 30-35psi, at 90-100 air temp vent temp should be about 55 and low side 40-45 psi. this is done with doors and windows closed and engine at 1000 rpms. If air flow is good and pressures are good then you have a door problem. .

 

[sag2]

Those pressures are fine but on the low side. I'm assuming it is 20 with compressor running and 40ish with compressor stopped for a few seconds as it cycles. If that is correct add half a can and see what your pressures and outlet temps do. You have to take humidity into account with your temps, so the more moisture in the air the higher your outlet temps will be.

 

[ichoplin]

I'll put in half a can and see what happens.
Thanks,
Ian

 

[DZink24]

to call the HVAC systems on these trucks bad is a serious understatement. pathetic is more like it. i too have to turn the blower fan all the way to the maximum speed setting to get even a slight increase in cooling. and i wont even blame the A/C, as i have to do the same in winter to get any amount of heat in the cab. i'd have to say that the blower is grossly underpowered, and way too loud for the amount of airflow coming from it. and yes, the other issues of stuck recirc door and frozen evaporators don't help matters any.

 

[Delrayz]

I recently used Issue 66 to repair my a/c at home, same issue when injectors failed. That alone was worth the cost of the subscription. Remember 460 air?... . 4 windows down 60 mph!

 

[ichoplin]

I put in half a can of refrigerant and didn't notice any improvement. Like you DZink24, even in the winter it takes more fan than I feel it should.
It's always something I guess. I just changed ball joints yesterday chasing down a clunking noise and the noise is still there.
My wife sure likes to remind me that the 02 I traded for this truck, even with 250,000 miles, was/is better than this one.
Ian

 

[wneubauer]

I had the dreaded "half A/C problem" a while back. No cool air on the passenger side. Low on freon was the answer. I was surprised to find my local Auto Zone loans dual side a/c manifolds with gauges. My pressure jumped around a lot but my system took a full can of refrigerant, as well as 2 oz of compressor oil at about 40lbs pressure on the low side. I had to closely manage the pressure as it would jump to 70 plus psi unless I kept the valve closed most of the way. Nice cold a/c now and we hit 97 yesterday here in North Texas. Good luck with a fix on this...

 

[ichoplin]

Just took my truck to the dealer to check for the "re-calibration" option. They told me all the doors were working properly and that it sounds like there's something blocking the vents.
I was thinking about blowing compressed air back through the vents in hopes of dislodging something. What do you all think?
Ian